The principle of operation of thermal Heating system with heat pump. Limits of efficiency of heat pumps

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 heat pump from other heat sources is the possibility of using 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:

- a condenser (a heat exchanger in which heat is transferred from the refrigerant to the elements of the room heating system: low-temperature radiators, fan coil units, warm floor, 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 operation is based on two phenomena: firstly, the absorption and release of heat by the liquid during the change state of aggregation are 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 more high temperature, giving off the heat of condensation to a heat receiver (for example, the heat carrier of the 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 refrigerator, 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 ).

<<< к разделу ТЕПЛОВОЙ НАСОС

<<< выбор вентиляционного оборудования

<<< назад к СТАТЬЯМ

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 with the help of a heat pump can be considered as some kind of 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 .

The second circuit, where the refrigerant circulates, has built-in heat exchangers - 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 operate 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.

Economical home heating systems are replacing traditional types of heating using gas, solid fuels and electricity. An air source heat pump is one of the most popular alternative solutions.

Among the advantages, we can note the low cost compared to geothermal installations, the possibility of using it when creating new heating systems and reconstructing old ones. The heat pump is especially in demand in "passive house" systems - residential premises designed on the principle of minimal heat consumption and the introduction of energy-saving technologies.

What is an air heat pump

The simplest heat pump was designed back in 1852 and was called the "heat multiplier". Lord Kelvin discovered the fundamental principles of operation that formed the basis of all modern heating equipment.

According to the laws of physics, heat is transferred from a heated body to something that has a lower temperature. But, the reverse process is possible, provided that additional energy is used for this.

A little later, the principle of the reverse Carnot cycle was discovered. The substance absorbs heat when evaporating, and after condensing on the surface, it releases it. It is this law that underlies refrigerators and air conditioners. The low-temperature air heat pump works like these household appliances, only in the "backward direction".

Some manufacturers of air conditioners use this principle, offering the consumer air conditioners that can work to heat a room. But air conditioning systems have low efficiency at negative temperatures, since the main purpose of the equipment is cooling, not heating.

Low temperature air source heat pumps for home heating work using this physical law. How is heating carried out in practice?

• Any, even a cooled body, has a high or low potential energy. Even at negative temperatures, the air contains a certain amount of heat. At -15°C, warmer than at -25°C. At -5°C, even more heat is in the air. The principle of operation of an air source heat pump allows you to extract the small amount of heat energy that remains in the winter season and transfer it to the room.
• An evaporator coil is located in the outdoor unit installed outdoors. Freon circulates inside the circuit - a liquid that freely passes into a gaseous state and vice versa. Freon evaporates, while absorbing the heat that remains even at low temperatures.
• The gas enters the compressor. The compressor creates high pressure and conditions for converting freon back into liquid.
• Under pressure, freon is heated and enters the condenser. In the block, the gas finally becomes a liquid, giving off all the heat that it received in the outdoor unit installed on the street.
• Freon, in a closed circuit, returns to the evaporator.

There is a dependence of the heat output of an air-to-water heat pump on the outdoor temperature. For this reason, manufacturers provide for the connection of additional heating equipment to the heat pump, which compensates for the lack of thermal energy when the outside temperature drops below -15°C. Work in cold conditions continues, although with less efficiency.

There are several types of air source heat pumps, differing in the principle used for space heating.

Thermal air/water pumps

Household heat supply systems and hot water supply, based on air heat pumps, are very effective for use in the temperate latitudes of the Russian Federation. The average COP (conversion ratio) is 3. It turns out that for every 1 kW spent, there are 3 kW of thermal energy produced.

The principle of operation is the same as in pumps of other modifications, but with certain differences:

• The condenser is placed inside the storage boiler connected to the heating and hot water system.
• The heat released during freon condensation is used to indirectly heat the coolant.
• With the help, the heated coolant enters the DHW system and heating.

The heat carrier heating intensity varies from +30°С to +60°С. At temperatures below -15°C, combined heat supply with an air heat pump is switched on, which is indispensable in cold climates. The lack of heat compensates for any boiler (electricity, gas, wood).

Since the installation of the outdoor unit is carried out on the street, an additional advantage will be the presence of an anti-freeze or defrosting function.

Air heating heat pumps

Air heating heat pumps are used to heat individual rooms. The principle of operation is in many ways similar to that used by a fan heater, only the capacitor plays the function of a heating coil.

The body of the indoor unit of the heat pump is similar to an air conditioner and can also work for air heating and cooling.

The consumer is offered various solutions to the issue of heating:

1. Installation of separate independent heaters.
2. Installation of several heat pumps united in a single network.

Heat pumps that heat a room with warm air have the following advantages:

• Maximum efficiency- no need for pre-heating of the coolant leads to a more economical consumption of electricity. The air is heated only to a temperature of 20-40 ° C, and this, in turn, provides a higher COP coefficient of 4.
• Rapid heating of the building- warm air begins to flow into the room a few seconds after switching on.
• Versatility– the equipment can be used as an air conditioner in summer. In the basic configuration, the function of cooling the room is provided.

When a negative temperature, critical for operation, is reached, the reserve heat source is automatically switched on when using an air HP. Thus, it is possible to compensate for the lack of thermal energy.

What is the difference between an air conditioner and an air heat pump

Indeed, the heat supply of premises with air source heat pumps in cold climates is in many ways similar to heating with conventional air conditioners. Internal and external blocks of a similar structure are used. Even in the internal structure there are many similarities. The difference is that indoor air HPs are more efficient at heating than at cooling, while air conditioners are the opposite.

You can feel the difference by comparing some of the characteristics of the equipment. The air conditioner stops working for heating already at a temperature of about -5 ° C. The operating mode of heat pumps is from -25°С to +45°С.

Since there is a tendency to improve air heat pumps for "passive" houses, soon, for a wide range of consumers, equipment models capable of maintaining performance when the temperature drops to -32 ° C will become available.

The difference between an air heat pump and an air conditioner lies in different technical characteristics, although there are many similarities between them.

How to choose an air heat pump

The choice of air HP is not as difficult as it might seem at first glance. When choosing a suitable model, you should focus on the following parameters:

1. heating type.
2. Heated area.
3. Manufacturer.

Additionally, determine which type of boiler will be used as a backup heat source. As practice shows, air heating with the connection of an electric boiler remains the most popular, which allows you to completely do without gas.

Which brand to choose an air type heat pump

If we analyze reviews of air source heat pumps, it is quite easy to identify equipment manufacturers that are in the greatest demand among domestic consumers:

• Stiebel Eltron is a German company that started its journey with the invention of the boiler. Over time, the range of products has been constantly expanding. Today, Stiebel Eltron is a leader in the production of water heating and heating equipment. The company offers two types of heat pumps: geothermal and air, working to heat the coolant and air.
• is another German manufacturer with over 30 years of experience in the production of air pumps. Viessmann stations connected to the water heating circuit deserve the greatest praise. As advantages - the presence of weather-dependent control sensors and many additional functions available in the basic configuration.
• Mitsubishi is a Japanese corporation that pioneered Zubadan technology. The solution made it possible to increase the COP (which is the highest among similar equipment) and expand the scope of applications. Mitsubishi was one of the first to offer the consumer air conditioners that work on heating and air source heat pumps. New technologies are constantly being introduced to increase the scope of products.
• – the company has developed a whole series of economical equipment geoTHERM. The range includes equipment that extracts heat from the earth, water, air and sunlight. Vaillant products are maximally adapted for use in the Russian Federation.

The cost of air HP with installation

The most expensive are heat pumps that heat the room with a coolant. The equipment will cost approximately 80 thousand rubles. (capacity 4.5 kW), up to 800 thousand rubles. (18.5 kW). Air heating heat pumps will cost from 50 thousand rubles. (per 4 kW) up to 120 thousand rubles. (for 8 kW).

The cost of installing an air heat pump is calculated individually, based on the technical parameters of the room and other factors.

The service life of the equipment is at least 20 years. The installed equipment pays for itself after 3-5 heating seasons, depending on the intensity of operation.

Pros and cons of using air source heat pumps

Literally 5 years ago, the domestic consumer had practically no experience of heating buildings in winter using air source heat pumps. I had to be content with statements and extremely positive comments posted on the websites of various manufacturers of equipment, which did not give a clear idea of ​​​​the capabilities of the equipment. Since then, a certain experience of use has appeared, which made it possible to identify not only the advantages, but also the disadvantages of air HPs.

Advantages

• The advantages of operating air-to-water heat pumps - the main advantage is complete independence from gas heating. In some regions of the Russian Federation, only bringing the pipeline to the house is more expensive than buying and installing a heat pump. No commissioning permits required.
• The systems are designed for installation in a passive house. Therefore, they were originally designed for economical heating of the house and heating of hot water. For 1 kW of electricity consumed, heat generation is 3-5 kW. A simple calculation of costs when using a heat pump will show that within 3-5 years the full payback of the equipment is achieved.
• The operation of the pump does not adversely affect human health. To ensure hygienic conditions, in systems using the principle of air heating, it is enough to clean the filters from time to time.

Flaws

• The high cost of equipment - a system with enough power to heat a residential building will cost 800-1200 thousand rubles, which is an unaffordable amount for most buyers.
• Dependence on ambient temperature. Features of autonomous heating of a house with an air source heat pump are directly related to the total amount of heat energy received. The lower the temperature outside, the worse the pump works. Starting from -15°C, you will have to connect a backup heat source.
  If we take into account that in most territories of the Russian Federation the average temperature regime is higher, then the expediency of this installation becomes clear. The optimal climatic zones for the use of air source heat pumps are parts of Russia with a temperate climate and an average temperature in winter of at least -15°C.

If we compare air HP and gas heating, especially considering that the latest models of pumping equipment are able to maintain performance at -32 ° C, the advantage of the former becomes obvious. Heat pumps are economical, do not require a permit for operation, are installed within 1 day and have a higher efficiency than gas equipment.

Recently, manufacturers have somewhat reduced the cost of thermal installations, which allowed even more buyers to appreciate the dignity of the stations. If the trend continues, we can expect increased demand for heat pumps.

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)

Let's take an ordinary household refrigerator as an example. 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, is much larger in order 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 technical task than cooling a small volume of a 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 low specific gravity of atmospheric gases. One cubic meter of 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, the 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 greater the depth, the higher the thermal efficiency of the probes inside the 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 HP in the southern regions, where the temperature rarely drops below 0 °C, but modern equipment is able to operate 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. The set temperature indoors is automatically maintained.

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, HP should be used in conjunction with additional heat sources.

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 a strong wind blows, 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 of various types of heat pumps, explains in detail the design of the air-to-water system.

Evgeny AfanasievChief Editor

Publication author 05.02.2019

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 on 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 the window opening with the open door of the "freezer" out. 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, the internal heating system is water);
• water-air (use of external water circuits and air-type heating systems);
• (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. A heat pump can heat a room in winter and cool it in summer. 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?

A heat pump is a device that allows you to transfer heat energy from a less heated body to a hotter body, increasing its temperature. In recent years, heat pumps have been in high demand as a source of alternative thermal energy, which allows you to get really cheap heat without polluting the environment.

Today they are produced by many manufacturers of heat engineering equipment, and the general trend is that in the coming years it is heat pumps that will take a leading position among heating equipment.

Typically, heat pumps use groundwater heat, the temperature of which is approximately at the same level all year round and is + 10C, the heat of the environment or water bodies.

The principle of their operation is based on the fact that any body that has a temperature above absolute zero has a thermal energy reserve that is directly proportional to its mass and specific heat capacity. It is clear that the seas, oceans, as well as underground waters, the mass of which is large, have a tremendous supply of thermal energy, the partial use of which for heating a home does not affect their temperature and the ecological situation on the planet.

It is possible to “pick up” thermal energy from any body only by cooling it. The amount of heat released in this case (in a primitive form) can be calculated by the formula

Q=CM(T2-T1), Where

Q- received heat

C-heat capacity

M- weight

T1 T2- the temperature difference by which the body was cooled

It can be seen from the formula that when one kilogram of coolant is cooled from 1000 degrees to 0 degrees, the same amount of heat can be obtained as when 1000 kg of coolant is cooled from 1C to 0C.

The main thing is to be able to use thermal energy and direct it to heating residential buildings and industrial premises.

The idea of ​​using the thermal energy of less heated bodies arose in the middle of the 19th century, and its authorship belongs to the famous scientist of that time, Lord Kelvin. However, he did not advance further than the general idea. The first design for a heat pump was proposed in 1855 and was owned by Peter Ritter von Rittenger. But he did not receive support and did not find practical application.

The "second birth" of the heat pump dates back to the mid-forties of the last century, when ordinary household refrigerators became widespread. It was they who prompted the Swiss Robert Weber to use the heat generated by the freezer to heat water for household needs.

The effect obtained was stunning: the amount of heat was so great that it was enough not only for hot water supply, but also for heating water for heating. True, at the same time, we had to work hard and come up with a system of heat exchangers that allows us to utilize the thermal energy released by the refrigerator.

However, in the beginning, Robert Weber's invention was seen as a funny idea, and was perceived as ideas from the modern-day famous Crazy Hands column. The real interest in it arose much later, when the question of finding alternative energy sources really arose. It was then that the idea of ​​a heat pump received its modern shape and practical application.

Modern heat pumps can be classified depending on the source of low-temperature heat, which can be soil, water (in an open or underground reservoir), as well as outdoor air.

The resulting thermal energy can be transferred to water and used for water heating and hot water supply, as well as air, and used for heating and air conditioning. Given this, heat pumps are divided into 6 types:

• From soil to water (ground to water)
• Ground to air (ground to air)
• From water to water (water to water)
• From water to air (water to air)
• From air to water (air to water)
• Air to air (air to air)

Each type of heat pump has its own characteristics of installation and operation.

Installation method and operation features of the heat pump GROUND-WATER

• Soil universal supplier of low-temperature thermal energy

The soil has a colossal reserve of low-temperature thermal energy. It is the earth's crust that constantly accumulates solar heat and at the same time is heated from the inside, from the core of the planet. As a result, at a depth of several meters, the soil always has a positive temperature. As a rule, in the central part of Russia we are talking about 150-170 cm. It is at this depth that the soil temperature has a positive value and does not fall below 7-8 C.

Another feature of the soil is that even in severe frosts it freezes gradually. As a result, the minimum soil temperature at a depth of 150 cm is observed when the calendar spring already sets in on the surface and the need for heat for heating decreases.

This means that in order to “take away” heat from the ground in the central region of Russia, heat exchangers for the accumulation of thermal energy must be located at a depth below 150 cm.

In this case, the heat carrier circulating in the heat pump system, passing through the heat exchangers, will be heated by the heat of the ground, then, entering the evaporator, transfer heat to the water circulating in the heating system and return for a new portion of thermal energy.

• What can be used as a coolant

The so-called "brine" is most often used as a heat carrier in ground-to-water heat pumps. It is made from water and ethylene glycol or propylene glycol. Freon is used in some systems, which greatly complicates the design of the heat pump and leads to an increase in its cost. The fact is that the heat exchanger of this type of pump must have a large heat exchange area, and therefore an internal volume, which requires an appropriate amount of coolant.

Freon use although it increases the efficiency of the heat pump, it requires absolute tightness of the system and its resistance to high pressure.

For systems with "brine" heat exchangers are usually made of polymer pipes, most often polyethylene, with a diameter of 40-60 mm. Heat exchangers are in the form of horizontal or vertical collectors.

It is a pipe laid in the ground at a depth below 170 cm. For this, you can use any undeveloped plot of land. For convenience and to increase the heat exchange area, the pipe is laid in a zigzag, loops, spiral, etc. In the future, this piece of land can be used for a lawn, flower bed or vegetable garden. It should be noted that the heat exchange between the soil and the collector is better in a humid environment. Therefore, the surface of the soil can be safely watered and fertilized.

It is believed that on average 1m2 of soil gives from 10 to 40 W of thermal energy. Depending on the need for thermal energy, there can be any number of collector loops.

The vertical collector is a system of pipes installed vertically in the ground. To do this, wells are drilled to a depth of several meters to tens or even hundreds of meters. Most often, the vertical collector is in close contact with groundwater, but this is not a necessary condition for its operation. That is, a vertically installed underground collector can be "dry".

The vertical collector, as well as the horizontal one, can have almost any design. The most widely used systems are of the "pipe in pipe" and "loop" type, through which the brine is pumped down and rises back to the evaporator.

It should be noted that vertical collectors are the most productive. This is explained by their location at a great depth, where the temperature is almost always at the same level and is 1-12 C. When used with 1 m2, you can get from 30 to 100 W of power. If necessary, the number of wells can be increased.

To improve the process of heat exchange between the pipe and the soil, the space between them is poured with concrete.

• Advantages and disadvantages of ground-to-water heat pumps

Installation of a ground-to-water heat pump requires significant financial investments, but its operation allows you to receive practically free thermal energy. This does not cause any damage to the environment.

Among the advantages of this type of heat pump should be noted:

• Durability: can work for several decades in a row without repair and maintenance
• Ease of operation
• Possibility of using the land for agriculture
• Fast payback: when heating premises of a large area, for example, from 300 m2 and above, the pump pays off in 3-5 years.

Given that the installation of a heat exchanger in the ground is a complex agrotechnical work, they must be carried out with a preliminary development of the project.

How a heat pump works

The heat pump consists of the following elements:

• Compressor operating from a conventional electrical network
• Evaporator
• Capacitor
• capillary
• thermostat
• The working fluid or refrigerant, the role of which is most suitable for freon

The principle of operation of a heat pump can be described using the well-known Carnot Cycle from a school physics course.

The gas (freon) entering the evaporator through the capillary expands, its pressure decreases, which leads to its subsequent evaporation, in which it, in contact with the walls of the evaporator, actively takes heat from them. The temperature of the walls decreases, which creates a temperature difference between them and the mass in which the heat pump is located. As a rule, this is groundwater, sea water, a lake or a mass of land. It is not difficult to guess that in this case, the process of transferring thermal energy from a more heated body to a less heated body, which in this case is the walls of the evaporator, begins. At this stage of operation, the heat pump “pumps out” heat from the heat carrier medium.

At the next stage, the refrigerant is sucked in by the compressor, then compressed and supplied under pressure to the condenser. In the process of compression, its temperature rises and can range from 80 to 120 C, which is more than enough for heating and hot water supply of a residential building. In the condenser, the refrigerant gives up its supply of thermal energy, cools down, turns into a liquid state, and then enters the capillary. Then the process is repeated.

To control the operation of the heat pump, a thermostat is used, with the help of which the power supply to the system is stopped when the room reaches the set temperature and the pump resumes operation when the temperature drops below a predetermined value.

The heat pump can be used as a source of thermal energy and can be used to arrange heating systems similar to heating systems based on a boiler or furnace. An example of such a system is shown in the diagram above.

It should be noted that the operation of the heat pump is possible only when it is connected to a source of electrical energy. In this case, it may be erroneously believed that the entire heating system is based on the use of electrical energy. In fact, to transfer 1 kW of thermal energy to the heating system, it is necessary to spend approximately 0.2-0.3 kW of electrical energy.

Advantages of a heat pump

Some of the benefits of a heat pump include:

• High efficiency
• Possibility of switching from heating mode to air conditioning mode and its subsequent use in summer for cooling rooms
• Ability to use an effective automatic control system
• environmental safety
• Compactness (the size is no more than a household refrigerator)
• Quiet operation
• Fire safety, which is especially important for heating country houses

Among the disadvantages of a heat pump, it should be noted that high cost and complexity of installation.