How a heat pump works. The principle of operation of heat pumps for heating a house. Features of heat pumps depending on the heat source

A heat pump is a universal device that functionally combines the characteristics of an air conditioner, a water heater and a heating boiler. This device does not use conventional fuel, its operation requires renewable sources from the environment - the energy of air, soil, water.

Therefore, a heat pump today is the most cost-effective unit, since its operation does not depend on the cost of fuel, it is also environmentally friendly, since the source of heat is not electricity or combustion products, but natural springs heat.

For a better understanding of how a heat pump works for heating a house, it is worth remembering the principle of operation of a refrigerator. Here the working substance evaporates, giving off cold. And in the pump, on the contrary, it condenses and produces heat.

How a heat pump works

The entire process of the system is presented in the form of a Carnot cycle - named after the inventor. It can be described as follows. The coolant passes through the working circuit - air, ground, water, their combinations , from where it is sent to the 1st heat exchanger - the evaporation chamber. Here it transfers the accumulated heat to the refrigerant circulating in the internal circuit of the pump.

Principle of operation heat pump home heating

The liquid refrigerant enters the evaporation chamber, where low pressure and temperature (5 0 C) convert it into a gaseous state. The next stage is the transition of gas to the compressor and its compression. As a result, the temperature of the gas rises sharply, the gas passes into the condenser, here it exchanges heat with the heating system. The cooled gas turns into a liquid, and the cycle repeats.

Advantages and disadvantages of heat pumps

The operation of heat pumps for home heating can be controlled by specially installed temperature controllers. The pump automatically turns on when the medium temperature drops below the set value and turns off if the temperature exceeds the set point. Thus, the device maintains a constant temperature in the room - this is one of the advantages of the devices.

The advantages of the device are its efficiency - the pump consumes a small amount of electricity and environmental friendliness, or absolute safety for the environment. The main advantages of the device:

• Reliability. The service life exceeds 15 years, all parts of the system have a high working resource, power surges do not harm the system.
• Safety. No soot, no exhaust, no open flames, no gas leakage.
• Comfort. The operation of the pump is silent, climate control and an automatic system, the operation of which depends on weather conditions, help to create coziness and comfort in the house.
• Flexibility. The device is modern stylish design, it can be combined with every home heating system.
• Versatility. It is used in private, civil construction. Because it has a wide power range. Due to which it can provide heat to rooms of any area - from small house to the cottage.

The complex structure of the pump determines its main drawback - the high cost of equipment and its installation. To install the device, you must excavation in large volumes.

Heat pumps - classification

The operation of a heat pump for heating a house is possible in a wide temperature range - from -30 to +35 degrees Celsius. The most common devices are absorption (they transfer heat through its source) and compression (the circulation of the working fluid occurs due to electricity). The most economical absorption devices, however, they are more expensive and have a complex design.

Classification of pumps by type of heat source:

1. Geothermal. They take heat from water or earth.
2. Air. They take heat from the air.
3. secondary heat. They take the so-called production heat - generated in production, during heating, and other industrial processes.

The heat carrier can be:

• Water from an artificial or natural reservoir, groundwater.
• Priming.
• Air masses.
• Combinations of the above media.

Geothermal pump - principles of design and operation

A geothermal pump for heating a house uses the heat of the soil, which it selects with vertical probes or a horizontal collector. Probes are placed at a depth of up to 70 meters, the probe is located at a small distance from the surface. This type of device is most efficient, since the heat source has a fairly high constant temperature throughout the year. Therefore, it is necessary to spend less energy on heat transportation.

Such equipment is expensive to install. The high cost of drilling wells. In addition, the area allotted for the collector should be several times larger than the area of ​​​​the heated house or cottage. Important to remember: the land where the collector is located cannot be used for planting vegetables or fruit trees- the roots of the plants will be supercooled.

Using water as a heat source

A pond is a source of a large amount of heat. For the pump, you can use non-freezing reservoirs from 3 meters deep or groundwater at a high level. The system can be implemented as follows: the heat exchanger pipe, weighed down with a load at the rate of 5 kg per 1 linear meter, is laid on the bottom of the reservoir. The length of the pipe depends on the footage of the house. For a room of 100 sq.m. the optimal length of the pipe is 300 meters.

In the case of using groundwater, it is necessary to drill two wells located one after the other in the direction of groundwater. A pump is placed in the first well, supplying water to the heat exchanger. Chilled water enters the second well. This so-called open circuit heat collection. Its main disadvantage is that the groundwater level is unstable and can change significantly.

Air is the most accessible source of heat

In the case of using air as a heat source, the heat exchanger is a radiator forcedly blown by a fan. If a heat pump works for heating a house using an air-to-water system, the user benefits from:

• Possibility to heat the whole house. Water, acting as a heat carrier, is diluted through heating devices.
• At minimal cost electricity - the ability to provide residents with hot water. This is possible due to the presence of an additional heat-insulated heat exchanger with storage capacity.
• Pumps of a similar type can be used to heat water in swimming pools.

If the pump operates on an air-to-air system, no heat carrier is used to heat the space. Heating is produced by the received thermal energy. An example of the implementation of such a scheme is a conventional air conditioner set to heating mode. Today, all devices that use air as a heat source are inverter-based. They convert alternating current to direct current, providing flexible control of the compressor and its operation without stopping. And this increases the resource of the device.

Heat pump - an alternative home heating system

Heat pumps - an alternative modern systems heating. They are economical, environmentally friendly and safe to use. However, the high cost installation work and equipment today do not allow the use of devices everywhere. Now you know how a heat pump works for heating a house, and having calculated all the pros and cons, you can decide on its installation.

Having refrigerators and air conditioners in their home, few people know that the principle of operation of a heat pump is implemented in them.

About 80% of the power supplied by a heat pump comes from ambient heat in the form of scattered solar radiation. It is his pump that simply “pumps” from the street into the house. The operation of a heat pump is similar to the principle of operation of a refrigerator, only the direction of heat transfer is different.

Simply put…

To cool a bottle of mineral water, you put it in the refrigerator. The refrigerator must “take away” part of the thermal energy from the bottle and, according to the law of conservation of energy, move it somewhere, give it away. The refrigerator transfers heat to a radiator, usually located on its back wall. At the same time, the radiator heats up, giving off its heat to the room. In fact, it heats the room. This is especially noticeable in small mini-markets in the summer, with several refrigerators in the room.

We invite you to imagine. Suppose that we will constantly put warm objects in the refrigerator, and it will, by cooling them, heat the air in the room. Let's go to the "extremes" ... Let's place the refrigerator in window opening freezer door open to the outside. The refrigerator radiator will be in the room. During operation, the refrigerator will cool the air outside, transferring the "taken" heat into the room. This is how a heat pump works, taking dispersed heat from the environment and transferring it to the room.

Where does the pump get the heat?

The principle of operation of a heat pump is based on the "exploitation" of natural low-grade heat sources from the environment.

They may be:

• just outside air;
• heat of reservoirs (lakes, seas, rivers);
• heat of the soil, groundwater (thermal and artesian).

How is a heat pump and a heating system with it arranged?

The heat pump is integrated into the heating system, which consists of 2 circuits + the third circuit - the system of the pump itself. A non-freezing coolant circulates along the external circuit, which takes heat from the surrounding space.

When it enters the heat pump, or rather its evaporator, the coolant gives off an average of 4 to 7 °C to the heat pump refrigerant. And its boiling point is -10 °C. As a result, the refrigerant boils, followed by a transition to a gaseous state. The coolant of the external circuit, already cooled, goes to the next “coil” through the system to set the temperature.

As part of the functional circuit of the heat pump "listed":

• evaporator;
• compressor (electric);
• capillary;
• capacitor;
• coolant;
• thermostatic control device.

The process looks like this!

The refrigerant "boiled" in the evaporator through the pipeline enters the compressor, powered by electricity. This "hard worker" compresses the gaseous refrigerant to high pressure, which, accordingly, leads to an increase in its temperature.

The now hot gas then enters another heat exchanger, which is called a condenser. Here, the heat of the refrigerant is transferred to the room air or heat carrier, which circulates through the internal circuit of the heating system.

The refrigerant cools down, at the same time turning into a liquid state. It then passes through a capillary pressure reducing valve, where it “loses” pressure and re-enters the evaporator.

The cycle is closed and ready to repeat!

Approximate calculation of the heating output of the installation

Within an hour, up to 2.5-3 m 3 of coolant flows through the external collector through the pump, which the earth is able to heat by ∆t = 5-7 °C.

To calculate the thermal power of such a circuit, use the formula:

Q \u003d (T_1 - T_2) * V_warm

V_heat - volumetric flow rate of the heat carrier per hour (m ^ 3 / h);

T_1 - T_2 - inlet and outlet temperature difference (°C) .

Varieties of heat pumps

According to the type of dissipated heat used, heat pumps are distinguished:

• ground-water (use closed ground contours or deep geothermal probes and a water heating system for a room);
• water-water (open wells are used for the intake and discharge of groundwater - the external circuit is not looped, internal system heating - water);
• water-air (use of external water circuits and heating system air type);
• (using the dissipated heat of external air masses, complete with the air heating system of the house).

Advantages and benefits of heat pumps

Economic efficiency. The principle of operation of a heat pump is based not on production, but on the transfer (transportation) of thermal energy, it can be argued that its efficiency is greater than one. What nonsense? - you will say. In the topic of heat pumps, the value appears - the coefficient of conversion (transformation) of heat (KPT). It is by this parameter that units of this type are compared with each other. Its physical meaning is to show the ratio of the amount of heat received to the amount of energy expended for this. For example, at KPT = 4.8, the electricity consumed by the pump in 1 kW will allow you to get 4.8 kW of heat with it free of charge, that is, a gift from nature.

Universal ubiquity of application. Even in the absence of available power lines, the heat pump compressor can be powered by a diesel drive. And there is "natural" heat in any corner of the planet - the heat pump will not remain "hungry".

Ecological purity of use. There are no combustion products in the heat pump, and its low energy consumption "exploits" power plants less, indirectly reducing harmful emissions from them. The refrigerant used in heat pumps is ozone-friendly and does not contain chlorocarbons.

Bidirectional mode of operation. The heat pump can winter time heat the room, and in the summer - cool. The “heat” taken from the premises can be used efficiently, for example, to heat water in a pool or in a hot water supply system.

Operational safety. In the principle of operation of a heat pump, you will not consider dangerous processes. The absence of open fire and harmful emissions dangerous for humans, the low temperature of the heat carriers make the heat pump a “harmless”, but useful household appliance.

Some nuances of operation

Efficient use of the principle of operation of a heat pump requires compliance with several conditions:

• the room that is heated must be well insulated (heat loss up to 100 W / m 2) - otherwise, taking heat from the street, you will heat the street for your own money;
• Heat pumps are beneficial for low-temperature heating systems. Under such criteria, underfloor heating systems (35-40 ° C) are excellent. The heat conversion coefficient significantly depends on the ratio of the temperatures of the inlet and outlet circuits.

Let's sum it up!

The essence of the principle of operation of a heat pump is not in production, but in the transfer of heat. This allows you to get a high coefficient (from 3 to 5) of thermal energy conversion. Simply put, each 1 kW of electricity used will “transfer” 3-5 kW of heat to the house. Is there anything else that needs to be said?

By the end of the 19th century, powerful refrigeration units, which could pump heat at least twice as much as the energy spent on putting them into action. It was a shock, because formally it turned out that a thermal perpetual motion machine is possible! However, upon closer examination, it turned out that perpetual motion is still far away, and low-grade heat produced using a heat pump and high-grade heat obtained, for example, by burning fuel, are two big differences. True, the corresponding formulation of the second law was somewhat modified. So what exactly are heat pumps? In a nutshell, a heat pump is a modern and high-tech appliance for heating and air conditioning. Heat pump collects heat from the street or from the ground and sends it to the house.

How a heat pump works

How a heat pump works simple: due to mechanical work or other types of energy, it provides the concentration of heat, previously evenly distributed over a certain volume, in one part of this volume. In the other part, respectively, a deficit of heat is formed, that is, cold.

Historically, heat pumps were first widely used as refrigerators - in fact, any refrigerator is a heat pump that pumps heat from refrigerator compartment outside (into the room or outside). There is still no alternative to these devices, and with all the variety of modern refrigeration technology, the basic principle remains the same: heat is pumped out of the refrigeration chamber due to additional external energy.

Naturally, almost immediately they noticed that the noticeable heating of the condenser heat exchanger (for a household refrigerator, it is usually made in the form of a black panel or a grill on the back wall of the cabinet) could also be used for heating. It was already the idea of ​​a heat pump based heater in its modern form- a refrigerator, on the contrary, when heat is pumped into a closed volume (room) from an unlimited external volume (from the street). However, in this area, the heat pump has a lot of competitors - starting with traditional wood stoves and fireplaces and ending with all kinds of modern heating systems. Therefore, for many years, while the fuel was relatively cheap, this idea was regarded as nothing more than a curiosity - in most cases it was absolutely unprofitable economically, and only very rarely was such use justified - usually for the utilization of heat pumped out by powerful refrigeration units in countries with not too cold climate. And only with the rapid rise in energy prices, the complication and rise in the cost of heating equipment and the relative cheapening against this background of the production of heat pumps, such an idea becomes economically viable in itself, because having paid once for a rather complex and expensive installation, then it will be possible to constantly save on reduced fuel consumption. Heat pumps are the basis of the growing ideas of cogeneration - the simultaneous production of heat and cold - and trigeneration - the production of heat, cold and electricity at once.

Since the heat pump is the essence of any refrigeration unit, we can say that the concept of " refrigerator' is his pseudonym. True, it should be borne in mind that despite the universality of the principles of operation used, the designs of refrigeration machines are still focused specifically on the production of cold, and not heat - for example, the generated cold is concentrated in one place, and the resulting heat can be dissipated in several different parts of the installation , because in a conventional refrigerator the task is not to utilize this heat, but simply to get rid of it.

Heat pump classes

Currently, two classes of heat pumps are most widely used. To one class can be attributed thermoelectric Peltier, and to another - evaporative, which, in turn, are divided into mechanical compressor (piston or turbine) and absorption (diffusion). In addition, interest is gradually increasing in the use of vortex tubes as heat pumps, in which the Ranque effect operates.

Heat pumps based on the Peltier effect

Peltier element

The Peltier effect lies in the fact that when a small constant voltage is applied to the two sides of a specially prepared semiconductor wafer, one side of this wafer heats up and the other cools. Here, in general, the thermoelectric heat pump is ready!

The physical essence of the effect is as follows. The plate of the Peltier element (aka "thermoelectric element", eng. Thermoelectric Cooler, TEC), consists of two layers of a semiconductor with different levels of electron energy in the conduction band. When an electron passes under the action of an external voltage into a higher-energy conduction band of another semiconductor, it must acquire energy. When he receives this energy, the place of contact of the semiconductors is cooled (when the current flows in the opposite direction, the opposite effect occurs - the place of contact of the layers heats up in addition to the usual ohmic heating).

Advantages of Peltier elements

The advantage of Peltier elements is the maximum simplicity of their design (what could be simpler than a plate to which two wires are soldered?) And the complete absence of any moving parts, as well as internal flows of liquids or gases. The consequence of this is absolute noiselessness of operation, compactness, complete indifference to orientation in space (provided sufficient heat dissipation is ensured) and very high resistance to vibration and shock loads. And the operating voltage is only a few volts, so a few batteries or a car battery are quite enough to work.

Disadvantages of Peltier elements

The main disadvantage of thermoelectric elements is their relatively low efficiency - it can be tentatively assumed that per unit of pumped heat they will need twice as much external energy supplied. That is, by supplying 1 J of electrical energy, we can remove only 0.5 J of heat from the cooled area. It is clear that all the total 1.5 J will be released on the "warm" side of the Peltier element and they will have to be taken to external environment. This is many times lower than the efficiency of compression evaporative heat pumps.

Against the background of such a low efficiency, other disadvantages are usually not so important, and this is a small specific productivity combined with a high specific cost.

Using Peltier elements

In accordance with their characteristics, the main field of application of Peltier elements is currently usually limited to cases where it is required not to cool something that is not too powerful, especially in conditions of strong shaking and vibrations and with severe restrictions on weight and dimensions, - for example, various components and parts of electronic equipment, primarily military, aviation and space. Perhaps, Peltier elements are most widely used in everyday life in low-power (5..30 W) portable automobile refrigerators.

Evaporative compression heat pumps

Working cycle diagram of an evaporative compression heat pump

The principle of operation of this class of heat pumps is as follows. The gaseous (in whole or in part) refrigerant is compressed by the compressor to a pressure at which it can turn into a liquid. Naturally, this heats up. The heated compressed refrigerant is fed into the condenser radiator, where it is cooled to the ambient temperature, giving it excess heat. This is the heating zone (back wall of the kitchen refrigerator). If at the inlet of the condenser a significant part of the compressed hot refrigerant still remained in the form of vapor, then when the temperature decreases during heat exchange, it also condenses and passes into a liquid state. The relatively cooled liquid refrigerant is fed into the expansion chamber, where, passing through a throttle or expander, it loses pressure, expands and evaporates, at least partially turning into a gaseous form, and, accordingly, cools down - significantly below the ambient temperature and even below the temperature in cooling zone of the heat pump. Passing through the channels of the evaporator panel, the cold mixture of liquid and vaporous coolant removes heat from the cooling zone. Due to this heat, the remaining liquid part of the refrigerant continues to evaporate, maintaining a stable low temperature of the evaporator and ensuring efficient heat removal. After that, the refrigerant in the form of vapor reaches the inlet of the compressor, which pumps it out and compresses it again. Then everything is repeated from the beginning.

Thus, in the “hot” section of the compressor-condenser-throttle, the refrigerant is under high pressure and predominantly in a liquid state, and in the “cold” section of the throttle-evaporator-compressor, the pressure is low, and the refrigerant is mainly in a vapor state. Both compression and rarefaction are created by the same compressor. On the opposite side of the compressor path, the high and low pressure separates a throttle that restricts the flow of refrigerant.

Powerful industrial refrigerators use poisonous but effective ammonia, efficient turbochargers and sometimes expanders as a refrigerant. In domestic refrigerators and air conditioners, the refrigerant is usually safer freons, and piston compressors and “capillary tubes” (throttles) are used instead of turbine units.

In the general case, a change in the state of aggregation of the refrigerant is not necessary - the principle will work for a constantly gaseous refrigerant - however, a large heat of change in the state of aggregation greatly increases the efficiency of the operating cycle. But if the refrigerant is in liquid form all the time, there will be no effect in principle - after all, the liquid is practically incompressible, and therefore neither increasing nor relieving pressure will change its temperature ..

Chokes and expanders

The terms "throttle" and "expander" used repeatedly on this page usually say little to people who are far from refrigeration technology. Therefore, a few words should be said about these devices and the main difference between them.

A choke in technology is a device designed to normalize the flow due to its forced restriction. In electrical engineering, this name has been assigned to coils designed to limit the rate of current rise and are usually used to protect electrical circuits from impulse noise. In hydraulics, throttles are usually called flow restrictors, which are specially designed channel constrictions with a precisely calculated (calibrated) clearance that provides the desired flow or the necessary flow resistance. A classic example such chokes are jets, widely used in carburetor engines to ensure the estimated flow of gasoline in the preparation of the fuel mixture. The throttle valve in the same carburetors normalized the flow of air - the second necessary ingredient in this mixture.

In refrigeration, a throttle is used to restrict the flow of refrigerant into the expansion chamber and maintain the conditions there for efficient evaporation and adiabatic expansion. Too much flow can generally lead to filling the expansion chamber with refrigerant (the compressor simply does not have time to pump it out) or, at least, to the loss of the necessary vacuum there. But it is the evaporation of the liquid refrigerant and the adiabatic expansion of its vapor that ensures the drop in the temperature of the refrigerant below the ambient temperature necessary for the operation of the refrigerator.

Principles of operation of the throttle (left), piston expander (center) and turbo expander (left).

In the expander, the expansion chamber has been somewhat modernized. In it, the evaporating and expanding refrigerant additionally makes mechanical work, moving the piston located there or rotating the turbine. In this case, the restriction of the refrigerant flow can be carried out due to the resistance of the piston or turbine wheel, although in reality this usually requires a very careful selection and coordination of all system parameters. Therefore, when using expanders, the main flow regulation can be carried out by a throttle (calibrated narrowing of the liquid refrigerant supply channel).

The turbo-expander is effective only at high flows of the working fluid; at a low flow, its efficiency is close to conventional throttling. A piston expander can operate efficiently with a much lower consumption of the working fluid, but its design is an order of magnitude more complicated than a turbine: in addition to the piston itself with all the necessary guides, seals and a return system, inlet and outlet valves with appropriate control are required.

The advantage of an expander over a throttle is more efficient cooling due to the fact that part of the thermal energy of the refrigerant is converted into mechanical work and is removed from the thermal cycle in this form. Moreover, this work can then be used for the benefit of business, say, to drive pumps and compressors, as is done in the Zysin refrigerator. But a simple throttle has an absolutely primitive design and does not contain a single moving part, and therefore, in terms of reliability, durability, as well as simplicity and cost of manufacture, it leaves the expander far behind. It is these reasons that usually limit the scope of expanders to powerful cryogenic technology, while household refrigerators use less efficient, but practically eternal chokes, called “capillary tubes” there and representing a simple copper tube of a sufficiently long length with a small diameter gap (usually from 0.6 to 2 mm), which provides the necessary hydraulic resistance for the calculated refrigerant flow.

Advantages of compression heat pumps

The main advantage of this type of heat pumps is their high efficiency, the highest among modern heat pumps. The ratio of energy supplied from the outside and pumped over can reach 1:3 - that is, for each joule of energy supplied from the cooling zone, 3 J of heat will be pumped out - compare with 0.5 J for Pelte elements! In this case, the compressor can stand separately, and the heat generated by it (1 J) does not have to be removed to the external environment in the same place where 3 J of heat pumped out from the cooling zone are given off.

By the way, there is a different from the generally accepted, but very curious and convincing theory of thermodynamic phenomena. So, one of her conclusions is that the work of compressing a gas can, in principle, be only about 30% of its total energy. And this means that the ratio of supplied and transferred energy of 1:3 corresponds to the theoretical limit and cannot be improved in principle with thermodynamic methods of heat transfer. However, some manufacturers already claim to achieve a ratio of 1:5 and even 1:6, and this is true - after all, in real refrigeration cycles, not only the compression of the gaseous refrigerant is used, but also a change in its state of aggregation, and it is the latter process that is the main one.. .

Disadvantages of compression heat pumps

The disadvantages of these heat pumps include, firstly, the very presence of a compressor, which inevitably creates noise and is subject to wear, and secondly, the need to use a special refrigerant and maintain absolute tightness throughout its entire working path. However, household compression refrigerators that have been continuously operating for 20 years or more without any repair are not at all uncommon. Another feature is a rather high sensitivity to position in space. On the side or upside down, both the refrigerator and the air conditioner are unlikely to work. But this is due to the features of specific designs, and not to general principle work.

As a rule, compression heat pumps and refrigeration units are designed with the assumption that all the refrigerant is in the vapor state at the compressor inlet. Therefore, if a large amount of unevaporated liquid refrigerant enters the compressor inlet, it can cause water hammer in it and, as a result, serious damage to the unit. The reason for this situation can be both equipment wear and too low a condenser temperature - the refrigerant entering the evaporator is too cold and evaporates too sluggishly. For a conventional refrigerator, this situation may arise if you try to turn it on in a very cold room (for example, at a temperature of about 0 ° C and below) or if it has just been brought into a normal room from frost. For a compression heat pump working for heating, this can happen if you try to warm a frozen room with it, even though it is also cold outside. Not very complex technical solutions eliminate this danger, but they increase the cost of the design, and during normal operation, mass household appliances there is no need for them - such situations do not arise.

Use of compression heat pumps

Due to its high efficiency, it is this type of heat pump that has become almost ubiquitous, displacing all others into various exotic applications. And even the relative complexity of the design and its sensitivity to damage cannot limit their widespread use - almost every kitchen has a compression refrigerator or freezer, or even more than one!

Evaporative absorption (diffusion) heat pumps

Working cycle of evaporators absorption heat pumps very similar to the operating cycle of the evaporative compression units discussed just above. The main difference is that if in the previous case the vacuum required for the evaporation of the refrigerant is created during the mechanical suction of vapors by the compressor, then in absorption units the evaporated refrigerant enters the absorber unit from the evaporator, where it is absorbed (absorbed) by another substance - the absorbent. Thus, the vapor is removed from the volume of the evaporator and a vacuum is restored there, which ensures the evaporation of new portions of the refrigerant. Necessary condition is such an “affinity” of the refrigerant and the absorbent that the forces of their binding during absorption can create a significant vacuum in the volume of the evaporator. Historically, the first and still widely used pair of substances is ammonia NH3 (refrigerant) and water (absorbent). When absorbed, ammonia vapor dissolves in water, penetrating (diffusing) into its thickness. From this process came the alternative names for such heat pumps - diffusion or absorption-diffusion.
In order to separate the refrigerant (ammonia) and the absorbent (water) again, the spent and ammonia-rich water-ammonia mixture is heated in the desorber by an external source of thermal energy up to boiling, then cooled somewhat. Water condenses first, but high temperature immediately after condensation, it is able to hold very little ammonia, so most of the ammonia remains in the form of vapor. Here, the pressurized liquid fraction (water) and the gaseous fraction (ammonia) are separated and separately cooled to ambient temperature. The cooled water with a low ammonia content is sent to the absorber, and the ammonia, when cooled in the condenser, becomes liquid and enters the evaporator. There, the pressure drops and the ammonia evaporates, cooling the evaporator again and taking heat from outside. The ammonia vapor is then recombined with water, removing excess ammonia vapor from the evaporator and maintaining a low pressure there. The solution enriched with ammonia is again sent to the desorber for separation. In principle, it is not necessary to boil the solution to desorb ammonia; simply heat it close to the boiling point, and the “excess” ammonia will evaporate from the water. But boiling allows the separation to be carried out most quickly and efficiently. The quality of such separation is the main condition that determines the vacuum in the evaporator, and therefore the efficiency of the absorption unit, and many tricks in the design are aimed precisely at this. As a result, in terms of the organization and number of stages of the working cycle, absorption-diffusion heat pumps are perhaps the most complex of all common types of such equipment.

The "highlight" of the principle of operation is that for the generation of cold, the heating of the working fluid is used here (up to its boiling). At the same time, the type of heating source is unimportant - it can even be an open fire (burner flame), so the use of electricity is not necessary. To create the necessary pressure difference, which determines the movement of the working fluid, sometimes mechanical pumps can be used (usually in powerful installations with large volumes of the working fluid), and sometimes, in particular in household refrigerators, elements without moving parts (thermosyphons).

Absorption-diffusion refrigeration unit (ADCA) of the Morozko-ZM refrigerator. 1 - heat exchanger; 2 - solution collector; 3 - hydrogen accumulator; 4 - absorber; 5 - regenerative gas heat exchanger; 6 - dephlegmator ("dehydrator"); 7 - capacitor; 8 - evaporator; 9 - generator; 10 - thermosyphon; 11 - regenerator; 12 - tubes of weak solution; 13 - steam outlet pipe; 14 - electric heater; 15 - thermal insulation.

The first absorption refrigeration machines (ABHM) on an ammonia-water mixture appeared in the second half of the 19th century. In everyday life, due to the toxicity of ammonia, they were not widely used at that time, but they were very widely used in industry, providing cooling down to -45 ° C. In single-stage ABCM, theoretically, the maximum cooling capacity is equal to the amount of heat spent on heating (in reality, of course, it is noticeably less). It was this fact that reinforced the confidence of the defenders of the very formulation of the second law of thermodynamics, which was mentioned at the beginning of this page. However, absorption heat pumps have now overcome this limitation. In the 1950s, more efficient two-stage (two condensers or two absorbers) lithium bromide ABCMs appeared (refrigerant - water, absorbent - lithium bromide LiBr). Three-stage variants of ABHM were patented in 1985-1993. Their prototypes are 30–50% more effective than two-stage ones and approach mass models of compression plants.

Advantages of absorption heat pumps

The main advantage of absorption heat pumps is the ability to use not only expensive electricity for their work, but also any heat source of sufficient temperature and power - superheated or exhaust steam, the flame of gas, gasoline and any other burners - up to exhaust gases and free solar energy.

The second advantage of these units, which is especially valuable in domestic applications, is the ability to create structures that do not contain moving parts, and therefore are practically silent (in Soviet models of this type, one could sometimes hear a quiet gurgling or slight hiss, but, of course, this does not go anywhere). compared to the noise of a running compressor).

Finally, in household models the working fluid (usually a water-ammonia mixture with the addition of hydrogen or helium) in the volumes used there does not pose a great danger to others even in the event of an emergency depressurization of the working part (this is accompanied by a very unpleasant stench, so it is impossible not to notice a strong leak, and a room with the emergency unit will have to leave and ventilate “automatically”; ultra-low concentrations of ammonia are natural and absolutely harmless). In industrial installations, the volumes of ammonia are large and the concentration of ammonia in case of leaks can be fatal, but in any case, ammonia is considered environmentally friendly - it is believed that, unlike freons, it does not destroy the ozone layer and does not cause a greenhouse effect.

Disadvantages of absorption heat pumps

The main disadvantage of this type of heat pumps- lower efficiency compared to compression.

The second disadvantage is the complexity of the design of the unit itself and the rather high corrosion load from the working fluid, either requiring the use of expensive and difficult to process corrosion-resistant materials, or reducing the unit's service life to 5..7 years. As a result, the cost of "hardware" is noticeably higher than that of compression plants of the same capacity (first of all, this applies to powerful industrial units).

Thirdly, many designs are very critical to placement during installation - in particular, some models of household refrigerators required installation strictly horizontally, and even with a deviation of several degrees they refused to work. The use of forced movement of the working fluid with the help of pumps largely eliminates the severity of this problem, but lifting with a silent thermosyphon and draining by gravity requires very careful alignment of the unit.

Unlike compression machines, absorption machines are not so afraid of too low temperatures - their efficiency is simply reduced. But it was not without reason that I placed this paragraph in the disadvantages section, because this does not mean that they can work in severe cold - in the cold, an aqueous solution of ammonia will simply freeze, unlike freons used in compression machines, the freezing point of which is usually below -100 ° C. True, if the ice does not break anything, then after thawing the absorption unit will continue to work, even if it has not been disconnected from the network all this time, because there are no mechanical pumps and compressors in it, and the heating power in household models is small enough to boil in the area the heater has not become too intense. However, it all depends on the features of a particular design ...

Use of absorption heat pumps

Despite somewhat lower efficiency and relatively higher cost compared to compression plants, the use of absorption heat engines is absolutely justified where there is no electricity or where there are large volumes of waste heat (exhaust steam, hot exhaust or flue gases, etc. - up to pre-solar heating). In particular, special models of refrigerators are produced, powered by gas burners, designed for motorists and yachtsmen.

Currently in Europe gas boilers sometimes they are replaced by absorption heat pumps with heating from a gas burner or diesel fuel - they allow not only to utilize the heat of combustion of fuel, but also to “pump up” additional heat from the street or from the depths of the earth!

As experience shows, in everyday life options with electric heating are also quite competitive, primarily in the low power range - somewhere from 20 to 100 watts. Smaller powers are the realm of thermoelectric elements, and at higher powers, the advantages of compression systems are still undeniable. In particular, among the Soviet and post-Soviet brands of refrigerators of this type, Morozko, Sever, Kristall, Kiev were popular with a typical volume of the refrigerator chamber from 30 to 140 liters, although there are also models of 260 liters (" Crystal-12"). By the way, when evaluating energy consumption, it is worth considering the fact that compression refrigerators almost always operate in a short-period mode, while absorption refrigerators usually turn on for a much longer period or even work continuously. Therefore, even if the rated power of the heater is much less than the power of the compressor, the ratio of the average daily energy consumption may be quite different.

Vortex heat pumps

Vortex heat pumps The Rank effect is used to separate warm and cold air. The essence of the effect is that the gas tangentially fed into the pipe at high speed is twisted and separated inside this pipe: cooled gas can be taken from the center of the pipe, and heated gas from the periphery. The same effect, although to a much lesser extent, also applies to liquids.

Advantages of vortex heat pumps

The main advantage of this type of heat pumps is the simplicity of design and high performance. The vortex tube contains no moving parts, and this provides it with high reliability and long service life. Vibration and position in space have practically no effect on its operation.

A powerful air flow well prevents freezing, and the efficiency of the vortex tubes is weakly dependent on the temperature of the inlet flow. The practical absence of fundamental temperature restrictions associated with hypothermia, overheating or freezing of the working fluid is also very important.

In some cases, the possibility of achieving a record high temperature separation in one stage plays a role: the literature gives figures for cooling by 200° and more. Usually one stage cools the air by 50..80°C.

Disadvantages of vortex heat pumps

Unfortunately, the efficiency of these devices is currently noticeably inferior to the efficiency of evaporative compression plants. In addition, for efficient operation, they require a high speed of supply of the working fluid. The maximum efficiency is noted at an input stream speed equal to 40..50% of the speed of sound - such a stream itself creates a lot of noise, and in addition, it requires a productive and powerful compressor- the device is also by no means quiet and rather capricious.

The absence of a generally accepted theory of this phenomenon, suitable for practical engineering use, makes the design of such units an empirical exercise in many respects, where the result is highly dependent on luck: “guessed or not guessed”. A more or less reliable result is obtained only by reproducing already created successful samples, and the results of attempts to significantly change certain parameters are not always predictable and sometimes look paradoxical.

Use of vortex heat pumps

However, the use of such devices is currently on the rise. They are justified primarily where there is already gas under pressure, as well as in various fire and explosion hazardous industries - after all, it is often much safer and cheaper to supply a flow of air under pressure to a hazardous area than to pull protected electrical wiring there and install electric motors in a special design .

Limits of efficiency of heat pumps

Why are heat pumps still not widely used for heating (perhaps the only relatively common class of such devices is inverter air conditioners)? There are several reasons for this, and in addition to the subjective ones associated with the lack of heating traditions using this technique, there are also objective ones, the main ones being frosting of the heat extractor and a relatively narrow temperature range for efficient operation.

In vortex (primarily gas) installations, there are usually no problems with hypothermia and freezing. They do not use a change in the state of aggregation of the working fluid, and a powerful air flow performs the functions of the "No Frost" system. However, their efficiency is much less than that of evaporative heat pumps.

hypothermia

In evaporative heat pumps, high efficiency is ensured by changing the state of aggregation of the working fluid - the transition from liquid to gas and vice versa. Accordingly, this process is possible in a relatively narrow temperature range. At too high temperatures, the working fluid will always remain gaseous, and at too low temperatures, it will evaporate with great difficulty or even freeze. As a result, when the temperature goes beyond the optimal range, the most energy-efficient phase transition becomes difficult or is completely excluded from the operating cycle, and the efficiency of the compression unit drops significantly, and if the refrigerant remains constantly liquid, then it will not work at all.

freezing

Extraction of heat from the air

Even if the temperatures of all the heat pump units remain within the required limits, during operation the heat extraction unit - the evaporator - is always covered with moisture droplets condensing from the surrounding air. But liquid water flows off it on its own, not particularly hindering heat transfer. When the temperature of the evaporator becomes too low, the condensate drops freeze, and the newly condensed moisture immediately turns into frost, which remains on the evaporator, gradually forming a thick snow coat - this is exactly what happens in the freezer of an ordinary refrigerator. As a result, the heat exchange efficiency is significantly reduced, and then it is necessary to stop the operation and thaw the evaporator. As a rule, in the evaporator of the refrigerator, the temperature drops by 25..50°C, and in air conditioners, due to their specifics, the temperature difference is smaller - 10..15°C. Knowing this, it becomes clear why most air conditioners cannot be adjusted to a temperature lower than +13..+17°С - this threshold is set by their designers to avoid icing of the evaporator, because the defrosting mode is usually not provided. This is also one of the reasons why almost all air conditioners with inverter mode do not work even at not very high negative temperatures - only recently models have begun to appear that are designed to work in frosts down to -25 ° C. In most cases, already at –5..–10°C, the energy costs for defrosting become comparable to the amount of heat pumped in from the street, and pumping heat from the street turns out to be inefficient, especially if the humidity of the outside air is close to 100% - then the external heat extractor is covered with ice especially fast.

Extraction of heat from soil and water

In this regard, as a non-freezing source of "cold heat" for heat pumps, heat from the depths of the earth has been increasingly considered recently. This does not mean the heated layers of the earth's crust, located at a depth of many kilometers, and not even geothermal water sources (although, if you are lucky and they are nearby, it would be foolish to neglect such a gift of fate). This refers to the "ordinary" heat of the soil layers located at a depth of 5 to 50 meters. As is known, in middle lane the soil at such depths has a temperature of the order of +5°C, which changes very little throughout the year. In more southern regions this temperature can reach +10°С and higher. Thus, the temperature difference between the comfortable +25°C and the ground around the heat extractor is very stable and does not exceed 20°C regardless of the frost outside the window (it should be noted that usually the temperature at the heat pump outlet is +50..+60°C, but and a temperature difference of 50°C is quite within the power of heat pumps, including modern household refrigerators, which calmly provide -18°C in the freezer at a temperature in the room above +30°C).

However, if you bury one compact but powerful heat exchanger, it is unlikely that the desired effect will be achieved. In fact, the heat extractor in this case acts as an evaporator of the freezer, and if there is no powerful heat inflow in the place where it is located (a geothermal source or an underground river), it will quickly freeze the surrounding soil, on which all heat pumping will end. The solution may be to extract heat not from one point, but evenly from a large underground volume, however, the cost of building a heat extractor covering thousands of cubic meters of soil at a considerable depth will most likely make this solution absolutely unprofitable economically. A less expensive option is to drill several wells with an interval of several meters from each other, as was done in an experimental "active house" near Moscow, but this is not cheap either - anyone who has made a well for water can independently estimate the costs of creating a geothermal fields of at least a dozen 30-meter wells. In addition, a constant heat extraction, although less strong than in the case of a compact heat exchanger, will still reduce the temperature of the ground around the heat extractors compared to the initial one. This will lead to a decrease in the efficiency of the heat pump during its long-term operation, and the period of temperature stabilization at a new level may take several years, during which the conditions for heat extraction will deteriorate. However, one can try to partially compensate for the winter heat loss by its enhanced injection to a depth in the summer heat. But even without taking into account the additional energy costs for this procedure, the benefits of it will not be too great - the heat capacity of the ground heat accumulator reasonable size is quite limited, and it is clearly not enough for the entire Russian winter, although such a supply of heat is still better than nothing. In addition, there are very great importance has a level, volume and speed of groundwater flow - abundantly moistened soil with a sufficiently high water flow rate will not allow to make “reserves for the winter” - flowing water will carry away the injected heat with it (even a meager movement of groundwater by 1 meter per day will carry away stored heat to the side by 7 meters, and it will be outside working area heat exchanger). True, the same groundwater flow will reduce the degree of cooling of the soil in winter - new portions of water will bring new heat, received by them away from the heat exchanger. Therefore, if there is a deep lake nearby, a large pond or a river that never freezes to the bottom, then it is better not to dig the soil, but to place a relatively compact heat exchanger in a reservoir - unlike stationary soil, even in a stagnant pond or lake, free water convection can provide much more efficient approach heat to the heat extractor from a significant volume of the reservoir. But here it is necessary to make sure that the heat exchanger will under no circumstances supercool to the freezing point of water and will not start to freeze ice, since the difference between convection heat transfer in water and the heat transfer of an ice coat is huge (at the same time, the thermal conductivity of frozen and unfrozen soil often differs not so much strongly, and an attempt to use the enormous heat of crystallization of water in the ground heat extraction under certain conditions can justify itself).

The principle of operation of a geothermal heat pump is based on the collection of heat from the soil or water, and transfer to the heating system of the building. To collect heat, the non-freezing liquid flows through a pipe located in the soil or reservoir near the building to the heat pump. A heat pump, like a refrigerator, cools the liquid (removes heat), while the liquid is cooled by approximately 5 °C. The liquid again flows through the pipe in the outer soil or water, regains its temperature, and again enters the heat pump. The heat extracted by the heat pump is transferred to the heating system and/or to hot water heating.

It is possible to extract heat from underground water - underground water with a temperature of about 10 ° C is supplied from the well to the heat pump, which cools the water to +1 ... + 2 ° C, and returns the water underground. Any object with a temperature above minus two hundred and seventy-three degrees Celsius has thermal energy - the so-called "absolute zero".

That is, a heat pump can take heat from any object - earth, water, ice, rocks, etc. If the building, for example, in summer, needs to be cooled (air-conditioned), then the reverse process occurs - heat is taken from the building and discharged into the ground (reservoir). The same heat pump can work in winter for heating, and in summer for cooling the building. Obviously, a heat pump can heat water for domestic hot water, air conditioning through fan coil units, heat a swimming pool, cool, for example, an ice rink, heat roofs and walkways from ice ...
One piece of equipment can perform all the functions of heating and cooling a building.

It becomes more difficult to pay for electricity and heat supply every year. When building or buying new housing, the problem of economical energy supply becomes especially acute. Due to periodically recurring energy crises, it is more profitable to increase the initial costs for high-tech equipment in order to receive heat for decades at a minimum cost.

The most cost-effective option in some cases is a heat pump for home heating, the principle of operation of this device is quite simple. It is impossible to pump heat in the truest sense of the word. But the law of conservation of energy allows technical devices to lower the temperature of a substance in one volume while simultaneously heating something else.

What is a heat pump (HP)

Take for example the usual household refrigerator. Inside the freezer, water quickly turns to ice. Outside is a grille that is hot to the touch. From it, the heat collected inside the freezer is transferred to the room air.

The same thing, but in reverse order, does TN. The radiator grill, located outside the building, has much big sizes to collect enough heat from the environment to heat the home. The coolant inside the tubes of the radiator or collector gives energy to the heating system inside the house, and then heats up again outside the house.

Device

Providing a house with heat is a more difficult task. technical task than to cool a small volume of the refrigerator, where a compressor with freezing and radiator circuits is installed. An air HP is almost as simple, which receives heat from the atmosphere and heats the internal air. Only fans are added to blow the circuits.

It is difficult to obtain a large economic effect from the installation of an air-to-air system due to the small specific gravity atmospheric gases. One cubic meter air weighs only 1.2 kg. Water is about 800 times heavier, so the calorific value also has a multiple difference. From 1 kW of electrical energy spent by an air-to-air device, only 2 kW of heat can be obtained, while a water-to-water heat pump provides 5–6 kW. To guarantee such a high coefficient of performance (COP) can HP.

The composition of the pump components:

1. Home heating system, for which it is better to use underfloor heating.
2. Boiler for hot water supply.
3. A condenser that transfers the energy collected outside to the heat carrier of the house heating.
4. An evaporator that takes energy from the coolant that circulates in the external circuit.
5. A compressor that pumps the refrigerant from the evaporator, converting it from a gaseous state to a liquid state, pressurizing it and cooling it down in the condenser.
6. Expansion valve, installed in front of the evaporator to control the flow of refrigerant.
7. The outer contour is laid on the bottom of the reservoir, buried in trenches or lowered into wells. For an air-to-air HP, the circuit is an external radiator grill, blown by a fan.
8. Pumps pump coolant through pipes outside and inside the house.
9. Automation for control according to a predetermined space heating program, which depends on changes in the outdoor temperature.

Inside the evaporator, the heat carrier of the external pipe register is cooled, giving off heat to the refrigerant of the compressor circuit, and then it is pumped through the pipes at the bottom of the reservoir by a pump. There it heats up and the cycle repeats again. In the condenser, heat is transferred to the heating system of the cottage.

Prices for different models of heat pumps

Heat pump

Principle of operation

The thermodynamic principle of heat transfer, discovered at the beginning of the 19th century by the French scientist Carnot, was later detailed by Lord Kelvin. But the practical use of their work, dedicated to solving the problem of home heating from alternative sources, appeared only in the last fifty years.

In the early 1970s, the first global energy crisis occurred. The search for economical ways of heating led to the creation of devices that can collect energy from the environment, concentrate it and send it to heat the house.

As a result, a HP design was developed with several interacting thermodynamic processes:

1. When the refrigerant of the compressor circuit enters the evaporator, the pressure and temperature of the freon almost instantly decrease. The resulting temperature difference contributes to the selection of thermal energy from the coolant of the external collector. This phase is called isothermal expansion.
2. Then adiabatic compression occurs - the compressor increases the pressure of the refrigerant. At the same time, its temperature rises to +70 °C.
3. Passing the condenser, freon becomes a liquid, since at elevated pressure it gives off heat to the in-house heating circuit. This phase is called isothermal compression.
4. When freon passes the throttle, pressure and temperature drop sharply. Adiabatic expansion occurs.

Heating the internal volume of the room according to the HP principle is possible only with the use of high-tech equipment equipped with automation to control all of the above processes. In addition, programmable controllers regulate the intensity of heat generation according to fluctuations in the outdoor temperature.

Alternative fuel for pumps

It is not necessary to use carbon fuel in the form of firewood, coal, gas for the operation of HP. The source of energy is the heat of the planet dissipated in the surrounding space, inside which there is a permanently operating nuclear reactor.

The solid shell of continental plates floats on the surface of hot liquid magma. Sometimes it breaks out during volcanic eruptions. Near the volcanoes there are geothermal springs, where even in winter you can swim and sunbathe. A heat pump is able to collect energy almost anywhere.

To work with various sources of dissipated heat, there are several types of HP:

1. "Air-to-air". It extracts energy from the atmosphere and heats the air masses indoors.
2. "Water-air". Heat is collected by an external circuit from the bottom of the reservoir for subsequent use in ventilation systems.
3. "Soil-water". Pipes for collecting heat are located horizontally underground below the freezing level, so that even in the most severe frost they receive energy to heat the coolant in the heating system of the building.
4. "Water-water". The collector is laid out along the bottom of the reservoir at a depth of three meters, collected heat heats the water circulating in the warm floors inside the house.

There is an option with an open external collector, when two wells can be dispensed with: one for groundwater intake, and the second for draining back into the aquifer. This option is possible only with good fluid quality, because the filters quickly become clogged if the coolant contains too many hardness salts or suspended microparticles. Before installation, it is necessary to do a water analysis.

If the drilled well silts up quickly or the water contains a lot of hardness salts, then the stable operation of the HP is ensured by drilling more holes in the ground. Loops of a sealed external circuit are lowered into them. Then the wells are plugged with the help of grouting from a mixture of clay and sand.

Use of ground pumps

You can get additional benefit from areas occupied by lawns or flower beds with the help of a ground-water HP. To do this, it is necessary to lay pipes in trenches to a depth below the freezing level to collect underground heat. The distance between parallel trenches is at least 1.5 m.

In the south of Russia, even in extremely cold winters, the ground freezes to a maximum of 0.5 m, so it is easier to remove the entire layer of earth at the installation site with a grader, lay the collector, and then fill the pit with an excavator. Shrubs and trees should not be planted at this place, the roots of which can damage the outer contour.

The amount of heat received from each meter of pipe depends on the type of soil:

• dry sand, clay - 10–20 W/m;
• wet clay - 25 W/m;
• moistened sand and gravel - 35 W/m.

The area of ​​land adjacent to the house may not be enough to accommodate an external register of pipes. Dry sandy soils do not provide sufficient heat flow. Then drilling of wells up to 50 meters deep is used to reach the aquifer. U-shaped collector loops are lowered into the wells.

The deeper the depth, the higher the rise thermal efficiency probes inside wells. The temperature of the earth's interior rises by 3 degrees every 100 m. The energy removal efficiency of a borehole collector can reach 50 W/m.

Installation and start-up of HP systems is a technologically complex set of works that can only be performed by experienced specialists. The total cost of equipment and component materials is much higher when compared with conventional gas heating equipment. Therefore, the payback period of the initial costs is stretched for years. But a house is built for decades, and geothermal heat pumps are the most profitable way of heating for country cottages.

Annual savings compared to:

• gas boiler - 70%;
• electric heating - 350%;
• solid fuel boiler - 50%.

When calculating the payback period of HP, it is worth considering the operating costs for the entire life of the equipment - at least 30 years, then the savings will many times exceed the initial costs.

Water-to-water pumps

Almost anyone can place polyethylene pipes of the collector at the bottom of a nearby reservoir. This does not require great professional knowledge, skills, tools. It is enough to evenly distribute the turns of the bay over the surface of the water. There should be a distance of at least 30 cm between the turns, and a flooding depth of at least 3 m. Then you need to tie the loads to the pipes so that they go to the bottom. Substandard brick or natural stone is quite suitable here.

The installation of a water-to-water HP collector will require significantly less time and money than when digging trenches or drilling wells. The cost of acquiring pipes will also be minimal, since the heat removal during convective heat transfer in the aquatic environment reaches 80 W/m. The obvious benefit of using HP is that there is no need to burn carbon fuel to generate heat.

An alternative way of heating a house is becoming more and more popular, because it has several more advantages:

1. Environmentally friendly.
2. Uses a renewable energy source.
3. After the completion of commissioning, there are no regular costs of consumables.
4. Automatically regulates the heating inside the house according to the outside temperature.
5. The payback period for initial costs is 5–10 years.
6. You can connect a boiler for hot water supply of the cottage.
7. In summer, it works as an air conditioner, cooling the supply air.
8. Service life of the equipment - more than 30 years.
9. Minimum energy consumption - generates up to 6 kW of heat when using 1 kW of electricity.
10. Full independence of heating and air conditioning of the cottage in the presence of an electric generator of any type.
11. Can be adapted to the smart home system for remote control, further energy saving.

Three independent systems are required for the operation of a water-to-water HP: external, internal and compressor circuits. They are combined into one scheme by heat exchangers in which various heat carriers circulate.

When designing the power supply system, it should be taken into account that electricity is consumed for pumping the coolant along the external circuit. The longer the length of the pipes, bends, turns, the less profitable the HP. The optimal distance from the house to the shore is 100 m. It can be extended by 25% by increasing the diameter of the collector pipes from 32 to 40 mm.

Air - split and mono

It is more profitable to use air heat pumps in the southern regions, where the temperature rarely drops below 0 ° C, but modern equipment able to work at -25 °C. Most often, split systems are installed, consisting of indoor and outdoor units. The external set consists of a fan that blows over the radiator grill, the internal one consists of a condenser heat exchanger and a compressor.

The design of split systems provides for reversible switching of operating modes using a valve. In winter, the outdoor unit is a heat generator, and in summer, on the contrary, it gives it to the outside air, working as an air conditioner. Air VTs are characterized by extremely simple installation of the external unit.

Other benefits:

1. The high efficiency of the outdoor unit is ensured by the large heat exchange area of ​​the evaporator grille.
2. Uninterrupted operation is possible at outdoor temperatures down to -25 °C.
3. The fan is located outside the room, so the noise level is within acceptable limits.
4. In summer, the split system works like an air conditioner.
5. Automatically supported set temperature indoors.

When designing the heating of buildings located in regions with long and frosty winters, it is necessary to take into account the low efficiency of air HPs at low temperatures. For 1 kW of electricity consumed, there is 1.5–2 kW of heat. Therefore, it is necessary to provide additional sources of heat supply.

The simplest installation of the HP is possible in the case of monoblock systems. Only tubes with coolant go inside the room, and all other mechanisms are located outside in one case. This design significantly increases the reliability of the equipment, and also reduces noise to less than 35 dB - this is at the level of a normal conversation between two people.

When installing a pump is uneconomical

It is almost impossible to find vacant plots of land in the city for the location of the external contour of a ground-to-water HP. It is easier to install an air source heat pump on the outer wall of the building, which is especially advantageous in southern regions. For colder areas with prolonged frosts, there is a possibility of icing on the external radiator grille of the split system.

The high efficiency of the HP is ensured under the following conditions:

1. The heated room must have insulated external enclosing structures. The maximum heat loss cannot exceed 100 W/m 2 .
2. HP is able to work effectively only with inertial low-temperature "warm floor" system.
3. In the northern regions, TN should be used in conjunction with additional sources heat.

When the outdoor temperature drops sharply, the inertial circuit of the “warm floor” simply does not have time to warm up the room. This is often the case in winter. In the afternoon the sun warmed up, on the thermometer -5 ° C. At night, the temperature can quickly drop to -15 ° C, and if it blows strong wind, then the frost will be even stronger.

Then it is necessary to install ordinary batteries under the windows and along the outer walls. But the temperature of the coolant in them should be twice as high as in the "warm floor" circuit. Additional energy in a country cottage can be provided by a fireplace with a water circuit, and an electric boiler in a city apartment.

It remains only to determine whether the HP will be the main or supplementary heat source. In the first case, it must compensate for 70% of the total heat loss of the room, and in the second - 30%.

Video

The video provides a visual comparison of the advantages and disadvantages various types heat pumps, the device of the air-to-water system is explained in detail.

Evgeny AfanasievChief Editor

Publication author 05.02.2019

Let's try to explain in the language of a simple layman what is " HEAT PUMP«:

Heat pump - This is a special device that combines a boiler, a source of hot water supply and an air conditioner for cooling. The main difference between a heat pump and other heat sources is the ability to use renewable low-grade energy taken from the environment (land, water, air, Wastewater) to cover heat needs during the heating season, heat water for hot water supply and cool the house. Therefore, the heat pump provides a highly efficient energy supply without gas and other hydrocarbons.

Heat pump is a device that works like a reverse chiller, transferring heat from a low temperature source to a higher temperature environment, such as your home's heating system.

Each heat pump system has the following main components:

- primary circuit - a closed circulation system that serves to transfer heat from the ground, water or air to the heat pump.
- secondary circuit - a closed system that serves to transfer heat from the heat pump to the heating, hot water or ventilation system (inflow heating) in the house.

How a heat pump works similar to the operation of an ordinary refrigerator, only in reverse. Refrigerator extracts heat from food products and transfers it outside (to the radiator located on its rear wall). A heat pump, on the other hand, transfers the heat accumulated in the soil, earth, reservoir, groundwater or air into your home. Like a refrigerator, this energy-efficient heat generator has the following main elements:

- condenser (heat exchanger in which heat is transferred from the refrigerant to the elements of the room heating system: low-temperature radiators, fan coil units, underfloor heating, radiant heating / cooling panels);
- throttle (a device that serves to reduce pressure, temperature and, as a result, close the heating cycle in the heat pump);
- evaporator (heat exchanger in which heat is taken from a low-temperature source to a heat pump);
- compressor (a device in which the pressure and temperature of the refrigerant vapor increases).

Heat pump arranged in such a way as to make the heat move in different directions. For example, during the heating of a house, heat is taken from some cold external source (land, river, lake, outdoor air) and transferred to the house. To cool (condition) the house, heat is taken from the warmer air in the house and transferred to the outside (discharged). In this respect, a heat pump is similar to a conventional hydraulic pump, which pumps liquid from the lower level to the upper level, while in normal conditions the liquid always moves from the upper level to the lower one.

Today, the most common are vapor compression heat pumps. The principle of their action is based on two phenomena: firstly, the absorption and release of heat by the liquid when the state of aggregation changes - evaporation and condensation, respectively; secondly, the change in the temperature of evaporation (and condensation) with a change in pressure.

In the evaporator of a heat pump, there is a working fluid - a refrigerant that does not contain chlorine - it is under low pressure and boils at a low temperature, absorbing heat from a low-grade source (for example, soil). Then the working fluid is compressed in the compressor, which is driven by an electric or other motor, and enters the condenser, where high pressure condenses at a higher temperature, giving off the heat of condensation to a heat sink (for example, a heating medium in a heating system). From the condenser, the working fluid through the throttle again enters the evaporator, where its pressure decreases, and the refrigerant boiling process begins anew.

Heat pump is able to take heat from various sources, for example, air, water, soil. Also, it can release heat into air, water or ground. A warmer environment that receives heat is called a heat sink.

Heat pump X/Y uses medium X as heat source and Y heat carrier. A distinction is made between pumps "air-to-water", "soil-to-water", "water-to-water", "air-to-air", "soil-to-air", "water-to-air".

Heat pump "ground-water":

Air-to-water heat pump:

The regulation of the heating system using heat pumps in most cases is carried out by turning it on and off at the signal of a temperature sensor that is installed in the receiver (when heating) or the source (when cooling) of heat. The heat pump is usually tuned by changing the cross section of the throttle (thermal expansion valve).

Like a refrigeration machine, a heat pump uses mechanical (electrical or other) energy to implement a thermodynamic cycle. This energy is used to drive the compressor (modern heat pumps up to 100 kW are equipped with highly efficient scroll compressors).

(transformation ratio or efficiency) of a heat pump is the ratio of the amount of heat energy that the heat pump produces to the amount of electrical energy that it consumes.

COP conversion factor depends on the temperature level in the evaporator and condenser of the heat pump. This value varies for various heat pump systems in the range from 2.5 to 7, that is, for 1 kW of electrical energy consumed, the heat pump generates from 2.5 to 7 kW of thermal energy, which is beyond the power of either a condensing gas boiler or any other generator heat.

Therefore, it can be argued that Heat pumps produce heat using a minimal amount of expensive electrical energy.

The energy saving and efficient use of a heat pump primarily depends on from where you decide to draw low-temperature heat, secondly - from the method of heating your house (water or air) .

The fact is that the heat pump works as a “transshipment base” between two thermal circuits: one heating at the inlet (on the evaporator side) and the second heated at the outlet (condenser).

All types of heat pumps are characterized by a number of features that you need to remember when choosing a model:

Firstly, a heat pump justifies itself only in a well-insulated house. The more warm house, the greater the benefit when using this device. As you understand, it is not entirely reasonable to heat the street with a heat pump, collecting crumbs of heat from it.

Secondly, the greater the temperature difference between the heat carriers in the inlet and outlet circuits, the lower the heat conversion coefficient (COP), that is, the lower the savings in electrical energy. That is why more profitable connection of the heat pump to low-temperature heating systems. First of all, we are talking about heating with a water-heated floor or infrared water ceiling or wall panels. But the more hot water the heat pump prepares for the outlet circuit (radiators or shower), the less power it develops and the more electricity it consumes.

Thirdly, in order to achieve greater benefits, the operation of a heat pump with an additional heat generator is practiced (in such cases, one speaks of using bivalent heating scheme ).

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Heat pumps for home heating: pros and cons

1. Features of heat pumps
2. Types of heat pumps
3. Geothermal type heat pumps
4. Advantages and disadvantages of heat pumps

One of the highly efficient ways of heating a country house is the use of heat pumps.

The principle of operation of heat pumps is based on the extraction of thermal energy from the soil, reservoirs, groundwater, and air. Heat pumps for home heating do not have a harmful effect on the environment. How similar heating systems look like can be seen in the photo.

Such an organization of home heating and hot water supply has been possible for many years, but it has only recently begun to spread.

Features of heat pumps

The principle of operation of such devices is similar to refrigeration equipment.

Heat pumps take heat, accumulate it and enrich it, and then transfer it to the heat carrier. A condenser is used as a heat generating device, and an evaporator is used to recover low potential heat.

The constant increase in the cost of electricity and the presentation of stringent requirements for environmental protection is the reason for the search for alternative methods of obtaining heat for heating houses and heating water.

One of them is the use of heat pumps, since the amount of heat energy received is several times higher than the electricity consumed (for more details: “Economical heating with electricity: pros and cons”).

If we compare heating with gas, solid or liquid fuels, with heat pumps, then the latter will be more economical. However, the very arrangement of the heating system with such units is much more expensive.

Heat pumps consume the electricity needed to run the compressor. Therefore, this type of building heating is not suitable if there are frequent problems with power supply in the area.

Heating a private house with a heat pump can have different efficiency, its main indicator is the conversion of heat - the difference between the electricity consumed and the heat received.

The difference between the temperature of the evaporator and the condenser is always present.

The larger it is, the lower the efficiency of the device. For this reason, when using a heat pump, you need to have a considerable source of low potential heat. Based on this, it follows that the larger the size of the heat exchanger, the lower the energy consumption. But at the same time, devices with large dimensions have a much higher cost.

Heating with a heat pump is found in many developed countries.

Moreover, they are also used to heat multi-apartment and public buildings - this is much more economical than the usual heating system in our country.

Types of heat pumps

These devices can be used over a wide temperature range. Usually they work normally at temperatures from -30 to + 35 degrees.

The most popular are absorption and compression heat pumps.

The latter of them use mechanical and electrical energy to transfer heat. Absorption pumps are more complex, but they are able to transfer heat using the source itself, thereby significantly reducing energy costs.

As for heat sources, these units are divided into the following types:

• air;
• geothermal;
• secondary heat.

Air source heat pumps for heating take heat from the surrounding air.

Geothermal heating systems use the thermal energy of the earth, underground and surface waters (for more details: "Geothermal heating: the principle of operation with examples"). Secondary heat pumps take energy from sewage, central heating - these devices are mainly used for heating industrial buildings.

This is especially beneficial if there are sources of heat that must be disposed of (read also: "Using the heat of the earth to heat the house").

Heat pumps are also classified according to the types of coolant, they can be air, soil, water, as well as their combinations.

Geothermal heat pumps

Heating systems that use heat pumps are divided into two types - open and closed. Open structures are designed to heat the water passing through the heat pump. After the coolant passes through the system, it is discharged back into the ground.

Such a system works ideally only if there is a significant amount of clean water, given the fact that its consumption will not harm the environment and will not conflict with current legislation. Therefore, before using a heating system that receives energy from groundwater, you should consult with the relevant organizations.

Closed systems are divided into several types:

1. Horizontal geothermal systems mean laying the collector in a trench below the freezing depth of the soil.

   This is approximately 1.5 meters. The collector is laid in rings in order to reduce the earthwork area to a minimum and provide a sufficient circuit in a small area (read: "Geothermal heat pumps for heating: the principle of the system design").

   This method is only suitable if there is a sufficient free area of ​​​​the site.

2. Geothermal structures with a vertical arrangement provide for the placement of a collector in a well up to 200 meters deep. This method is used when it is not possible to locate the heat exchanger over a large area, which is necessary for a horizontal well.

   Also, geothermal systems with vertical wells are made in the case of an uneven landscape of the site.

3. Geothermal water systems involve placing a collector in a reservoir at a depth below the freezing level. Laying is done in rings. Such systems cannot be used if the reservoir is small or not deep enough.

   It must be borne in mind that if the reservoir freezes at the level where the collector is located, the pump will not be able to work.

Heat pump air water - features, details on the video:

Advantages and disadvantages of heat pumps

Heating a country house with a heat pump has both positive and negative sides. One of the main advantages of heating systems is environmental friendliness.

Also, heat pumps are economical, unlike other heaters that consume electricity. Thus, the amount of generated thermal energy is several times greater than the consumed electricity.

Heat pumps are characterized by increased fire safety, they can be used without creating additional ventilation.

Since the system has a closed circuit, financial expenses during operation are minimized - you have to pay only for the consumed electricity.

The use of heat pumps also allows you to cool the room in the summer - this is possible due to the connection of fan coils to the collector and the "cold ceiling" system.

These devices are reliable, and the control of the work processes is fully automatic. Therefore, the operation of heat pumps does not require special skills.

The compact dimensions of the devices are also important.

The main disadvantage of heat pumps:

• high cost and significant installation costs. It is unlikely that you will be able to design heating with a heat pump with your own hands without special knowledge. It will take more than one year for the investment to pay off;
• the service life of the devices is approximately 20 years, after which it is highly likely that a major overhaul will be required.

  This, too, will cost dearly;

• the price of heat pumps is several times higher than the cost of gas, solid or liquid fuel boilers. A lot of money will have to be paid for drilling wells.

But on the other hand, heat pumps do not require regular maintenance, as is the case with many other heating appliances.

Despite all the advantages of heat pumps, they are still not widely used. This is due, first of all, to the high cost of the equipment itself and its installation. It will be possible to save money only if you create a system with a horizontal heat exchanger, if you dig trenches yourself, but this will take more than one day. As for the operation, the equipment is very profitable.

Heat pumps are an economical way to heat buildings without harming the environment.

They cannot be widely used due to the high cost, but this may change in the future. In developed countries, many owners of private houses use heat pumps - there the government encourages concern for the environment, and the cost of this type of heating is low.

A thermal ground or geothermal pump is one of the most energy efficient alternative energy systems. Its operation does not depend on the time of year and ambient temperature, as for an air-to-air pump, it is not limited by the presence of a reservoir or a well with groundwater near the house, like a water-to-water system.

The ground-to-water heat pump, which uses the heat taken from the soil to heat the coolant in the heating system, has the highest and constant efficiency, as well as the energy conversion coefficient (COP).

Its value is 1:3.5-5, that is, each kilowatt of electricity spent on the operation of the pump is returned by 3.5-5 kilowatts of thermal energy. Thus, the heating power of a soil pump makes it possible to use it as the only source of heat even in a house with a large area, of course, when installing a unit of appropriate power.

A submersible soil pump requires equipment of a soil circuit with a circulating coolant to extract the heat from the earth.

There are two options for its placement: a horizontal soil collector (a system of pipes at a shallow depth, but a residually large area) and a vertical probe placed in a well from 50 to 200 m deep.

The efficiency of heat exchange with the soil significantly depends on what kind of soil lies - moisture-filled soil gives off much more heat than, for example, sandy soil.

The most common are pumps operating on the principle of ground-water, in which the coolant stores the energy of the soil and, as a result of passing through the compressor and heat exchanger, transfers it to water as a heat carrier in the heating system. Prices for soil pumps of this type correspond to their high efficiency and performance.

Submersible Soil Pump

Any complex high-tech units, such as GRAT ground pumps, as well as ground source heat pumps, require the attention of professionals.

Heat pump

We offer a full range of services for the implementation, installation and maintenance of heating and hot water systems based on heat pumps.

To date, European countries and China are especially popular among the producing countries of such units on the market.

The most famous models of heat pumps: Nibe, Stiebel Eltron, Mitsubishi Zubadan, Waterkotte. The domestic ground heat pump is no less in demand.

Our company prefers to work only with equipment from reliable European manufacturers: Viessmann and Nibe.

The heat pump extracts the accumulated energy from various sources - ground, artesian and thermal waters - waters of rivers, lakes, seas; purified industrial and domestic wastewater; ventilation emissions and flue gases; soil and the earth's interior - transfers and converts into energy at higher temperatures.

Heat pump – highly economical, environmentally friendly technology for heating and comfort

Thermal energy exists all around us, the problem is how to extract it without spending significant energy resources.

Heat pumps extract the accumulated energy from various sources - ground, artesian and thermal waters - waters of rivers, lakes, seas; purified industrial and domestic wastewater; ventilation emissions and flue gases; soil and the earth's interior - transfers and converts into energy at higher temperatures.

The choice of the optimal heat source depends on many factors: the size of the energy needs of your home, the installed heating system, the natural conditions of the region where you live.

The device and principle of operation of the heat pump

The heat pump functions like a refrigerator - just the other way around.

The refrigerator transfers heat from the inside to the outside.

The heat pump transfers the heat stored in the air, soil, subsoil or water into your home.

The heat pump consists of 4 main units:

Evaporator,

Capacitor,

Expansion valve (discharge valve-
throttle, lowers pressure),

Compressor (increases pressure).

These units are connected by a closed pipeline.

The piping system circulates a refrigerant that is a liquid in one part of the cycle and a gas in the other.

Earth's interior as a deep heat source

The earth's interior is a free heat source that maintains the same temperature all year round. The use of the heat of the earth's interior is an environmentally friendly, reliable and safe technology for providing heat and hot water to all types of buildings, large and small, public and private. The level of investment is quite high, but in return you will receive a safe to operate, with minimal maintenance requirements, an alternative heating system with the longest possible service life. Heat conversion coefficient (see. page 6) is high, reaches 3. The installation does not require much space and can be implemented on a small plot of land. The volume of restoration work after drilling is insignificant, the impact of the drilled well on the environment is minimal. There is no impact on the groundwater level as groundwater is not consumed. Thermal energy is transferred to the convection water heating system and used for hot water supply.

Ground heat - nearby energy

Heat accumulates in the surface layer of the earth during the summer.

The use of this energy for heating is advisable for buildings with high energy costs. The greatest amount of energy is extracted from soil with a high moisture content.

Ground source heat pump

Water heat sources

The sun heats water in the seas, lakes and other water sources.

Solar energy accumulates in water and bottom layers. Rarely the temperature drops below +4 °C. The closer to the surface, the more the temperature varies throughout the year, while at depth it is relatively stable.

Heat pump with water heat source

The heat transfer hose is laid on the bottom or in the bottom soil, where the temperature is still slightly higher,
than water temperature.

It is important that the hose be fitted with a weight to prevent
hose rises to the surface. The lower it lies, the lower the risk of damage.

The water source as a heat source is very efficient for buildings with relatively high heat demand.

Groundwater heat

Even groundwater can be used to heat buildings.

This requires a drilled well, from where water is pumped into the heat pump.

When using ground water, high demands are placed on its quality.

Ground water heat pump as heat source

After passing through the heat pump, water can be transported to a drainage channel or a well. Such a solution may lead to an undesirable decrease in the groundwater level, as well as reduce the operational reliability of the installation and have a negative impact on nearby wells.

Now this method is used less and less.

Groundwater can also be returned to the ground also through partial or complete infiltration.

Such a good heat pump

Heat conversion coefficient The higher the efficiency of the heat pump, the more profitable it is. Efficiency is determined by the so-called heat conversion coefficient or thermal transformation coefficient, which is the ratio of the amount of energy generated by the heat pump to the amount of energy spent on the heat transfer process. For example: The temperature transformation coefficient is 3. This means that the heat pump delivers 3 times more energy than it consumes. In other words, 2/3 is received "for free" from the heat source. How to make a heat pump for home heating with your own hands: the principle of operation and schemes The higher the energy demand of your home, the more money you save. Note The value of the temperature transformation coefficient is affected by the presence/ignorance in the calculations of the parameters of additional equipment (circulation pumps), as well as various temperature conditions. The lower the temperature distribution, the higher the temperature transformation coefficient becomes, heat pumps are most efficient in heating systems with low temperature characteristics.

When selecting a heat pump for your heating system, it is unprofitable to orient power indicators of the heat pump for the maximum power requirements (to cover the energy consumption in the heating circuit on the coldest day of the year). Experience shows that the heat pump should generate about 50-70% of this maximum, the heat pump should cover 70-90% (depending on the heat source) of the total annual energy demand for heating and hot water supply. At low external temperatures, the heat pump is used with the available boiler equipment or the peak closer, which the heat pump is equipped with.

Comparison of the costs of installing a heating system for an individual house based on a heat pump and a liquid fuel boiler.

For analysis, let's take a house with an area of ​​​​150-200 sq.m.

The most common variant of a modern country house for permanent use today.
The use of modern building materials and technologies ensures the amount of heat loss of the building at the level of 55 W/sq.m of floor.
To cover the total needs for thermal energy spent on heating and hot water supply of such a house, it is necessary to install a heat pump or boiler with a thermal output of approximately 12 kW / h.
The cost of the heat pump itself or the oil-fired boiler is only a fraction of the costs that must be incurred to commission the heating system as a whole.

The following is a far from complete list of the main associated costs for the installation of a turnkey heating system based on an oil-fired boiler, which are absent in the case of a heat pump:

air vent filter, fixed package, safety group, burner, boiler piping system, weather-compensated automatic control panel, emergency electric boiler, fuel tank, chimney, boiler.

All this in total is at least 8000-9000 euros. Taking into account the need to arrange the boiler room itself, the cost of which, taking into account all the requirements of the supervisory authorities, is several thousand euros, we come to a conclusion that is paradoxical at first glance, namely, the practical comparability of the initial capital costs when installing a turnkey heating system based on a heat pump and a liquid fuel boiler.

In both cases, the cost is close to 15 thousand euros.

Given the following undeniable advantages of a heat pump, such as:
Profitability. With the cost of 1 kW of electricity 1 ruble 40 kopecks, 1 kW of thermal power will cost us no more than 30-45 kopecks, while 1 kW of thermal energy from the boiler will cost 1 ruble 70 kopecks (with the price of diesel fuel 17 rubles / l);
Ecology. Environmentally friendly heating method for both the environment and people in the room;
Safety. There is no open flame, no exhaust, no soot, no smell of diesel fuel, no gas leakage, no fuel oil spill.

There are no fire hazardous storages for coal, firewood, fuel oil or diesel fuel;

Reliability. A minimum of moving parts with a high resource of work. Independence from the supply of furnace material and its quality. Virtually maintenance free. The service life of the heat pump is 15 - 25 years;
Comfort. The heat pump operates silently (no louder than a refrigerator);
Flexibility. The heat pump is compatible with any circulating heating system, and the modern design allows it to be installed in any room;

An increasing number of owners of individual houses choose a heat pump for heating both in new construction and when upgrading an existing heating system.

Heat pump device

The near-surface technology of using low-potential thermal energy using a heat pump can be considered as a technical and economic phenomenon or a real revolution in the heat supply system.

Heat pump device. The main elements of a heat pump are the evaporator, compressor, condenser and flow regulator connected by a pipeline - a choke, expander or swirl tube (Fig. 16).

Schematically, a heat pump can be represented as a system of three closed circuits: in the first, external, a heat sink circulates (a heat carrier that collects the heat of the environment), in the second - a refrigerant (a substance that evaporates, taking away the heat of the heat sink, and condenses, giving off heat to the heat sink) , in the third - a heat sink (water in the heating and hot water supply systems of the building).

16. Heat pump device

The external circuit (collector) is a pipeline laid in the ground or in water, in which an antifreeze liquid circulates. It should be noted that both natural heat (outside air; heat of ground, artesian and thermal waters; waters of rivers, lakes, seas and other non-freezing natural reservoirs) and technogenic origin (industrial discharges, treatment facilities, heat from power transformers and any other waste heat).

The temperature required for the operation of the pump is usually 5-15 .

In the second circuit, where the refrigerant circulates, heat exchangers are built-in - an evaporator and a condenser, as well as devices that change the pressure of the refrigerant - a throttle spraying it in the liquid phase (a narrow calibrated hole) and a compressor compressing it already in the gaseous state.

Working cycle. The liquid refrigerant is forced through the throttle, its pressure drops, and it enters the evaporator, where it boils, taking away the heat supplied by the collector from the environment.

Further, the gas into which the refrigerant has turned is sucked into the compressor, compressed and, heated, is pushed into the condenser. The condenser is the heat dissipating unit of the heat pump: here the heat is received by the water in the heating circuit system. The gas is then cooled and condensed in order to be again depressurized in the expansion valve and returned to the evaporator. After that, the work cycle is repeated.

In order for the compressor to work (maintain high pressure and circulation), it must be connected to electricity.

But for every kilowatt-hour of electricity consumed, the heat pump generates 2.5-5 kilowatt-hours of thermal energy.

Heat pump for heating: principle of operation and advantages of use

This ratio is called the transformation ratio (or heat conversion ratio) and serves as an indicator of the efficiency of the heat pump.

The value of this value depends on the difference between the temperature levels in the evaporator and the condenser: the greater the difference, the smaller it is. For this reason, the heat pump should use as much of the low-grade heat source as possible without trying to cool it down too much.

Types of heat pumps.

Heat pumps come in two main types - closed and open circuit.

Open circuit pumps they use water from underground sources as a heat source - it is pumped through a drilled well into a heat pump, where heat exchange takes place, and the cooled water is discharged back into the underwater horizon through another well.

This type of pump is beneficial in that groundwater maintains a stable and fairly high temperature all year round.

Closed circuit pumps there are several types: vertical and g horizontal(Fig.17).

Pumps with a horizontal heat exchanger have a closed external circuit, the main part of which is dug horizontally into the ground, or laid along the bottom of a nearby lake or pond.

The depth of the pipes underground in such installations is up to a meter. This method of obtaining geothermal energy is the cheapest, but its use requires a number of technical conditions that are not always available in the developed area.

The main one is that the pipes should be laid so as not to interfere with the growth of trees, agricultural work, so that there is a low probability of damage to underwater pipes during agricultural or other activities.

Rice. 17. Surface geothermal system with heat exchange

Pumps with vertical heat exchanger include an external contour dug deep into the ground - 50-200 m.

This is the most efficient type of pump and produces the cheapest heat, but it is much more expensive to install than the previous types. The benefit in this case is due to the fact that at a depth of more than 20 meters, the temperature of the earth is stable all year round and is 15-20 degrees, and it only grows with increasing depth.

Air conditioning with heat pumps. One of the important qualities of heat pumps is the ability to switch from heating mode in winter to air conditioning mode in summer: only fan coil units are used instead of radiators.

A fancoil is an indoor unit into which a heat or coolant is supplied and air driven by a fan, which, depending on the temperature of the water, is either heated or cooled.

Includes: heat exchanger, fan, air filter and control panel.

Since fan coil units can work both for heating and for cooling, several piping options are possible:
- S2 - pipe - when water plays the role of heat and coolant and their mixing is allowed (and, as an option, a device with an electric heater and a heat exchanger that works only for cooling);
- S4 - pipe - when the coolant (for example, ethylene glycol) cannot be mixed with the coolant (water).

The power of fan coil units for cold ranges from 0.5 to 8.5 kW, and for heat - from 1.0 to 20.5 kW.

They are equipped with low-noise (from 12 to 45 dB) fans with up to 7 rotation speeds.

Perspectives. The widespread use of heat pumps is hampered by insufficient public awareness. Potential buyers are frightened by rather high initial costs: the cost of the pump and installation of the system is $ 300-1200 per 1 kW of required heating power. But a competent calculation convincingly proves the economic feasibility of using these installations: investments pay off, according to rough estimates, in 4-9 years, and heat pumps serve for 15-20 years before major repairs.