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Such an unit as a heat pump The principle of operation has a similar with household appliances - refrigerator and air conditioning. Approximately 80% of its power he borrow ambient. Pump pumps heat from the street into the room. His work is similar to the principle of functioning of the refrigerator, only the direction of heat transfer is different.

For example, to cool the water bottle, people put it in the refrigerator, then the household appliance partially "takes" from this subject heat and now, according to the law of energy conservation should give it. But where? It's simple, for this in the refrigerator there is a radiator, as a rule, on its back wall. In turn, the radiator, heating, gives the heat of the room in which it is worth. Thus, the refrigerator heats the room. To what extent it warms, you can feel in small stores in hot summer when several refrigeration units are included.

And now a little fantasy. Suppose that the refrigerator constantly put warm objects in the refrigerator, and it heats the room or it was located in the window opening, opened the freezer door outside, while the radiator was indoors. In the process of its work, a household device, cooling the air on the street, will simultaneously carry thermal energy that is outside, in the building. Exactly such has a thermal pump principle of action.

Where does the pump be warm?

The heat pump is functioning, due to the operation of natural low-precanced sources of thermal energy, among which:

• ambient air;
• reservoirs (rivers, lakes, sea);
• soil and soil artesian and thermal waters.

Heating system with thermal pump

When a heat pump is used for heating - the principle of operation is based on integration into the heating system. It consists of two contours to which the third, representing the design of the pump.

The heat carrier, which takes on heat from the environment, circulates by an external contour. It enters the pump evaporator and gives the refrigerant about 4 -7 ° C, while its boiling point is -10 ° C. As a result, the refrigerant boils and then goes into a gaseous state. Already cooled coolant in the external circuit is sent to the next turn for a temperature set.

The functional contour of the thermal pump from:

• evaporator;
• refrigerant;
• electrical compressor;
• condenser;
• capillary;
• thermostat control device.

The process, as the heat pump works, looks like this:

• the refrigerant after boiling, moving through the pipeline, enters the compressor working with the help of electricity. This device compresses the refrigerant, which is in a gaseous state, to a high pressure, which causes an increase in its temperature;
• hot gas enters another heat exchanger (capacitor), in which the heat of the refrigerant is given to the coolant circulating on the inner contour of the heating system, or air indoor;
• cooling, the refrigerant goes into a liquid state, after which it passes through the capillary reducing valve, losing pressure, and then turns out to be in the evaporator again;
• thus, the cycle ended, and the process is ready to repeat.

Approximate calculation of heat production

For an hour through a pump on an external collector, a 2.5-3 cubic meter of the coolant passes, which the land is able to heat Δt \u003d 5-7 ° C (read also: ""). To calculate the thermal power of this circuit, you should use the formula:

Q \u003d (T 1 - T 2) x V, where:
V - coolant consumption per hour (m 3 / hour);
T 1 - T 2 is the temperature difference at the input and input (° C).

Types of thermal pumps

Depending on the type of dispersion heat consumed, heat pumps are:

• soil-water - for their work in a water heating system, closed soil contours or geothermal probes are used at a depth (Read more: "");
• water-water - the principle of operation in this case is based on the use of open wells for the fear of groundwater and their reset (read: ""). In this case, the outer contour is not stolen, and the heating system in the house is water;
• water-air - establish external water circuits and use the heating structures of the air type;
• air-air - for their operation, use multiple heat of external air masses plus the air heating system at home.

The advantages of thermal pumps

1. Efficiency and efficiency. The principle of operation of thermal pumps depicted in the photo is not based on the production of thermal energy, but on transferring it. Thus, the efficiency of the heat pump should be greater than one. But how is it possible? In relation to the operation of heat pumps, the value is used, which is called the heat transformation ratio or abbreviated CCT. The characteristics of the units of this type are compared to this parameter.The physical meaning of the magnitude is to determine the relationship between the amount of heat obtained and the energy spent on its production. For example, if the KPT coefficient is 4.8, this means that 1kW electricity expended by the pump allows 4.8 kW heat, and free of charge from nature.
2. Universal ubiquitous application. In the absence of power lines available for consumers, the pump compressor operation is provided using a diesel drive. Since natural heat is everywhere, the principle of operation of this device allows you to use it everywhere.
3. Ecology. The principle of operation of the heat pump is based on a small consumption of electricity and the absence of combustion products. The refrigerant used by the aggregate does not contain chlorouparrodes and is completely ozone-safe.
4. Bidirectional functioning mode. In the heating period, the heat pump is capable of heating the building, and in the summer it is cooling it. The warmth, selected by the room, can be used to provide home by hot water supply, and if there is a swimming pool, warm water in it.
5. Safe operation. There are no hazardous processes in the operation of heat pumps - there is no open fire, and harmful to human health substances are not distinguished. The coolant does not have a high temperature, which makes the device safe and at the same time useful in everyday life.
6. Automatic control of the heating process of rooms.

Principle of operation of the heat pump, a fairly detailed video:

Some features of pump operation

To ensure efficient operation of the heat pump, it is necessary to comply with a number of conditions:

• the room should be qualitatively insulated (heat loss can not exceed 100 W / m²);
• the heat pump is beneficial to use for low-temperature heating systems. This criterion corresponds to a warm floor system, since its temperature is 35-40 ° C. CCT largely depends on the ratio between the temperature of the input circuit and the output.

The principle of operation of heat pumps is to transfer heat, which allows the coefficient of the energy conversion rate from 3 to 5. In other words, each 1 kW of the used electricity brings 3-5 kW of heat to the house.

Among the main directions of development of engineering equipment for private households, it is possible to highlight an increase in productivity with ergonomics and expansion of functionality. In this case, the developers are increasingly paying attention to the energy efficiency of technical equipment of communication systems. The heating infrastructure is considered the most costly, therefore it is particularly interested in its assessment of its company. Among the most tangible results of work in this direction, a thermal air pump is distinguished, which replaces the traditional heating equipment, increasing

Features of thermal air pumps

The main difference is to generate heat. Most involve the use of traditional energy as a source. However, in the case of air pumps and for heating, and to ensure hot water supply, most of the energy is consumed from natural resources directly. About 20% of the total potential is discharged from familiar stations. Thus, air thermal houses economically spend energy and cause a smaller damage to an ecological environment. It is noteworthy that the conceptual versions of the pumps were designed to provide office space and enterprises. But in the future, technology covered the segment of household equipment, allowing ordinary users to use favorable sources of thermal energy.

Principle of operation

The entire workflow is based on the cycling of the refrigerant taking the source. Heating occurs after the condensation of air flows, which are compressed in the compressor. Next, the refrigerant in the liquid state goes directly into the heating system. Now you can consider the principle of circulation of the coolant in the design of the pump. In the gaseous state, the refrigerant is sent to the heat exchanger enclosed in the internal unit. There he gives the heat of the room and is converted into a liquid. At this stage, the receiver is entering into business, which also supplies the air thermal pump. The principle of operation of the standard version of this device assumes that in this block, the liquid will exchange heat with a refrigerant, which has a low pressure. As a result of this process, the temperature of the formed mixture decreases again, and the liquid will go to the receiver output. At the time of passing the gaseous refrigerant through a pipe with reduced pressure in the receiver, its overheating is enhanced, after which it fills the compressor.

Specifications

The main technical indicator is power, which in the case of home models varies from 2.5 to 6 kW. Semi-industrials can also be used in communication with private houses, if the power potential is required more than 10 kW. As for the sizes of pumps, they correspond to traditional air conditioners. Moreover, they can be confused in appearance with a split system. The standard unit may have parameters 90x50x35 cm. The mass also corresponds to typical climatic settings - an average of 40-60 kg. Sure, main question Regards the spectrum of covered temperatures. Since the air thermal pump is focused on the heating function, the upper limit is considered target and on average reaches 30-40 ° C. True, there are also versions with combined functions, which also produce cooling of the room.

Varieties of structures

There are several heat generation concepts with an air pump. As a result, the design is raised specifically for the requests of a specific generation scheme. The most popular model involving interaction in one system of air flow and water carrier. The main classification shares the design by the type of functional blocks. So, there is a thermal air pump in a monoblock case, and there are both models involving the output of the system with the help of auxiliary segment. By and large, both models repeat the principle of operation of conventional air conditioners, only their functions and performance raised to a new level.

Application of modern technology

Innovative developments largely led to the development of classical climatic installations. In particular, Mitsubishi uses a spiral compressor in its models with a two-phase refrigerant injection, which allows the equipment to perform its function regardless of temperature conditions. Even at -15 ° C, thermal air pump from Japanese developers demonstrates performance up to 80%. In addition, the latest models are supplied with new control systems, which provides more convenient, safe and efficient installation of installations. With all the technological equipment, the possibility of its integration into traditional heating systems with boilers and boilers is preserved.

Making air pumps with their own hands

First of all, you must purchase a compressor for the future installation. It is fixed in the wall and performs the function of the outdoor unit of the ordinary split system. Next, the complex is complemented by a capacitor that can be made independently. For this operation, a copper "serpent" is required thickness of about 1 mm thick, which must then be placed in a plastic or metal case - for example, a tank or tank. The prepared tube is wound on the core, which can perform a balloon with dimensions, allowing it to integrate it into the tank. Using perforated, you can form your turns with the same intervals, which will make more efficiently air, many homemade craftsmen perform and followed by the download of Freon, which will perform a refrigerant. Next, the assembled design connects to the heating system of the house through an external circuit.

By the end of the XIX century, powerful refrigeration plants appeared, which could pump heat at least twice as much as the energy was spent on bringing them into action. It was a shock, because formally came out that the thermal eternal engine is possible! However, with attentive consideration, it turned out that until the eternal engine is still far away, and the low-precision heat extracted with the help of a heat pump, and high-precantial heat obtained, for example, when burning fuel, are two large differences. True, the corresponding formulation of the second start was somewhat modified. So what is thermal pumps? In a nutshell, a thermal pump is a modern and high-tech device for heating and air conditioning. Heat pump Collects warmth from the street or from the ground and sends to the house.

Principle of operation of the heat pump

Principle of operation of the heat pump Prost: due to the mechanical work or other types of energy, it provides heat concentration, previously uniformly distributed by some volume, in one part of this volume. In another part, accordingly, the deficit of heat is formed, that is, the cold.

Historically, heat pumps for the first time began to be widely used as refrigerators - in fact, any refrigerator is a heat pump that patching heat from refrigeration chamber outward (in the room or outside). There is still no alternative to these devices so far, and with all the diversity of modern refrigeration technology, the basic principle remains the same: pumping heat from the refrigerator at the expense of additional external energy.

Naturally, almost immediately drew attention to the fact that noticeable heating of the heat exchanger of the capacitor (at the domestic refrigerator, it is usually made in the form of a black panel or a lattice on the back wall of the cabinet) could also be used for heating. It was already the idea of \u200b\u200ba heater based on a heat pump in her modern video - Refrigerator on the contrary, when heat is injected into a closed volume (room) from an unlimited external volume (from the street). However, in this area of \u200b\u200bcompetitors, the heat pump is full - starting with the traditional wood stoves and fireplaces and ending with all sorts of modern heating systems. Therefore, for many years, while the fuel was relatively cheap, this idea was considered as no more than curious, - in most cases it was absolutely unprofitable economically, and only extremely rarely such use was justified - usually for heat disposal, pumped into powerful refrigerator in countries with Not too cold climate. And only with the rapid increase in energy prices, complication and rise in prices heating equipment and relative reduction in this background of the production of heat pumps, such an idea becomes an economically advantageous in itself, because by paying once for a rather complicated and expensive installation, then you can constantly save on the abbreviated fuel consumption. Thermal pumps are the basis of the popularity of the ideas of cogeneration - simultaneous heat generation and cold - and triegeratives - developing at once heat, cold and electricity.

Since the thermal pump is the essence of any refrigeration unit, it can be said that the concept of "refrigerating machine" is its pseudonym. True, it should be borne in mind that despite the universality of the principles of work used, the design of refrigeration machines is still focused on the production of cold, and not heat - for example, the cold produced concentrates in one place, and the heat obtained can be dispelled in several different parts of the installation because in the usual refrigerator there is a task not to dispose of it warm, but just get rid of it.

Classes of thermal pumps

Currently, two classes of thermal pumps are most widely used. To one class, the thermoelectric on the Peltier effect can be attributed, and to the other - evaporative, which, in turn, are divided into mechanical compressor (piston or turbine) and absorption (diffusion). In addition, gradually increases interest in the use of vortex pipes as thermal pumps, which run the effect of the wound.

Heat pumps on Peltier Effect

Peltier element

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

The physical essence of the effect is as follows. Peltier element plate (he "Thermoelectric Element", English. Thermoelectric Cooler, TEC) consists of two semiconductor layers with different levels of electrons in the conduction zone. When switching an electron under the action of external voltage to a higher-energy inspection area of \u200b\u200banother semiconductor, it must purchase energy. Upon receipt of this energy, there is a cooling of the semiconductors' contact location (when current flows in the opposite direction, there is a reverse effect - the place of contact of the layer is heated additionally to the usual ohmic heating).

Advantages of elements of Peltier

The advantage of Peltier elements is the maximum simplicity of their design (which may be easier to the plate to which two wiring are soldered?) And the complete absence of any moving parts, as well as internal fluids or gases. The consequence of this is the absolute silentness of work, compactness, complete indifference to the orientation in space (subject to ensuring sufficient heat sink) and very high resistance to vibration and shock loads. Yes, and the working voltage is only a few volts, so several batteries or car batteries are quite enough for operation.

Disadvantages of Peltier elements

The main disadvantage of thermoelectric elements is their relatively low efficiency - approximately we can assume that by the unit of the transfer heat they will be twice as much as the subordinate external energy. That is, by submitting 1 J Electric Energy, we can remove only 0.5 J heat from the cooled area. It is clear that all the total 1.5 J will be allocated on the "warm" side of the Peltier element and they will need to be left to the external environment. This is many times lower than the effectiveness of compression evaporative pumps.

Against the background of such a low efficiency, the other deficiencies are usually not so important - and this is a small specific productivity in combination with a high specific value.

Use of pelier elements

In accordance with their features, the main area of \u200b\u200bapplication of Peltier elements is usually limited to cases when it is required not to cool anything not too powerful, especially in conditions of severe shaking and vibrations and with rigid mass limits and dimensions - for example, Various nodes and parts of electronic equipment, primarily military, aviation and space. Perhaps the most widespread in everyday life of Peltier got into low-power (5..30 W) portable automotive refrigerators.

Evapory Compression Heat Pumps

Diagram of the working cycle of the evaporative compression thermal pump

Principle of operation of this class of heat pumps is as follows. Gaseous (in whole or in part) The refrigerant is compressed by the compressor to the pressure at which it can turn into a liquid. Naturally, it heats up. The heated compressed refrigerant is supplied to the radiator of the condenser, where it is cooled to the ambient temperature, giving it excessive heat. This is the heating zone (rear wall of the kitchen refrigerator). If a significant part of the compressed hot refrigerant remains in the form of a pair at the input of the capacitor, then, with a decrease in temperature during the heat exchange, it also condenses and goes into a liquid state. The relatively chilled liquid refrigerant is supplied to the expansion chamber, where, passing through the choke or the item, it loses pressure, expands and evaporates, at least partially turning into a gaseous form, and, accordingly, cools, is significantly lower than the ambient temperature and even below the temperature in The cooling zone of the heat pump. Passing through the channels of the evaporator panel, the cold mixture of liquid and vapor coolant selects heat from the cooling zone. Due to this heat, the remaining region of the refrigerant continues to evaporate, maintaining a stable low temperature of the evaporator and ensuring effective selection of heat. After that, the refrigerant in the form of a pair gets to the entrance of the compressor, which pumped up and again squeezes it. Then everything is repeated first.

Thus, on the "hot" section, the refrigerant compressor-throttle is under high pressure and mainly in a liquid state, and on the "cold" section of the choke-evaporator-compressor pressure low, and the refrigerant is mainly in a vapor state. And compression, and the vacuum is created by the same compressor. With the opposite side of the path of the high and low pressure, the part of the high and low pressure zone shares the throttle limiting the refrigerant flow.

In powerful industrial refrigerators, poisonous, but effective ammonia, productive turbochargers and sometimes detaDers are used as refrigerant. In household refrigerators and air conditioners, the refrigerant usually are more secure freons, and instead of turbo units are used piston compressors and "capillary tubes" (chokes).

In general, the change in the aggregate refrigerant state is optional - the principle will be working and for a constantly gaseous refrigerant - however, the high heat change of the aggregate state increases many times the efficiency of the working cycle. But if the refrigerant will be in liquid form all the time, the effect will not be fundamentally - after all, the fluid is almost incompressible, and therefore neither increase nor removing the pressure will change its temperature ..

Throthes and detaDers

The terms "Chokes" and "DetaDer" are repeatedly used on this page usually little people tell people far from refrigeration. Therefore, we should say a few words about these devices and the main difference between them.

The choke in the technique is called a device intended for the rationing of the flow due to its forced restriction. In the electrical engineering, this name has been fixed behind the coils designed to limit the rate of increasing current and usually used to protect the power supply from pulsed interference. In hydraulics, throtters, as a rule, are called the flow limiters, which are specially created channel narrowings with precisely calculated (calibrated) lumen, providing the desired flow or the required stream resistance. Classic example Such chokes are gypsum, widely used in carburetor engines to ensure the calculated flow of gasoline during the preparation of the fuel mixture. The throttle in the same carburetors rationed the air flow - the second necessary ingredient of this mixture.

In refrigeration technology, the choke is used to limit the refrigerant flow into the expansion chamber and maintain the conditions there necessary for effective evaporation and adiabatic expansion. Too much stream can generally lead to the filling of the expansion chamber by the refrigerant (the compressor simply does not have time to pump it) or at least to the loss of the necessary vacuum. But it is the evaporation of a liquid refrigerant and the adiabatic expansion of its vapors ensures the refrigerant temperature dropping the refrigerant temperature below the ambient temperature.

Principles of operation of the throttle (left), the piston detaard (center) and turboodera (left).

In the detaarder, the expansion chamber is somewhat modernized. In it, the evaporating and expanding refrigerant additionally performs mechanical work, moving the piston or rotating the turbine located there. The restriction of the refrigerant flow can be carried out due to the resistance of the piston or the wheel of the turbine, although in fact it usually requires a very careful selection and coordination of all parameters of the system. Therefore, when using items, the main normalization of the flow can be carried out by choke (calibrated narrowing of the supply channel of the liquid refrigerant).

Turbodetander is effective only at large working fluids, with a small stream, its effectiveness is close to normal throttling. The piston detaode can effectively work with a much lower working body consumption, however the design of it is an order of magnitude more complex to the turbine: in addition to the piston itself with all the necessary guides, seals and return system, intake and exhaust valves are required with appropriate control.

The advantage of the detaner before the choke is more efficient cooling due to the fact that part of the heat of the refrigerant turns into mechanical work and is given out of the thermal cycle in this form. Moreover, this work can then be used with benefit for business, let's say, to drive pumps and compressors, as is done in the "Zysin refrigerator". But a simple choke has an absolutely primitive design and does not contain a single moving part, and therefore in reliability, durability, as well as the simplicity and cost of manufacture leaves the workman far behind. It is these reasons usually limit the scope of the methods of the methods of powerful cryogenic technique, and in domestic refrigerators are used less efficient, but almost eternal chokes called "capillary tubes" and representing a simple copper tube a sufficiently large length with a lumen of small diameter (usually from 0.6 to 2 mm), which provides the necessary hydraulic resistance to calculate the refrigerant flow.

Advantages of compression thermal pumps

The main advantage of this type of thermal pumps is their high efficiency, the highest among modern thermal pumps. The ratio of the distance from the outside and pumping energy can reach 1: 3 - that is, each joiler of the suburbs of the energy from the cooling zone will be daded 3 J heat - compare with 0.5 J in pelt elements! At the same time, the compressor can stand separately, and the heat generated by it (1 J) is not necessary to divert into the external environment in the same place where 3 J heat is given, dumped from the cooling zone.

By the way, there is a different and convincing theory of thermodynamic phenomena differing from the generally accepted. So, one of its findings is that the work on gas compression in principle can only be about 30% of its total energy. And this means that the ratio of the suburban and pumping energy 1: 3 corresponds to the theoretical limit and during thermodynamic methods of heat pumping cannot be improved in principle. However, some manufacturers already declare the achievement of 1: 5 ratio and even 1: 6, and this corresponds to reality - after all, in real refrigeration cycles, it is not just a compression of a gaseous refrigerant, but also a change in its aggregate state, and it is the last process that is the main process. .

Disadvantages of compression thermal pumps

The disadvantages of these heat pumps can be attributed, firstly, the very presence of a compressor, inevitably creating noise and susceptible to wear, and secondly, the need to use a special refrigerant and compliance with absolute tightness throughout its work path. However, household compression refrigerators, continuously operating for 20 years and more without any repair, are not at all uncommon. Another feature is quite high sensitivity to the position in space. On the side or upside down, the refrigerator is hardly earned and air conditioning. But this is due to the peculiarities of specific structures, and not with the general principle of work.

As a rule, compression heat pumps and refrigeration units are designed to calculate that at the entrance of the compressor, the entire refrigerant is in a vapor state. Therefore, to enter the inlet of the compressor of a large number of uniform liquid refrigerant can cause hydraulic punch in it and, as a result, a serious breakdown of the unit. The reason for such a situation can be both dismisses of equipment, and too low the temperature of the condenser - the refrigerant incoming to the evaporator is too cold and evaporates too sluggish. For an ordinary refrigerator, such a situation may occur if trying 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 entered into a normal room with a frost. For a compression heat pump heated, this may happen if they try to warm them to the watery room despite the fact that it is also cold outside. Not very complex technical solutions eliminate this danger, but they increase the design of the construction, and when operating the mass household appliances They have no need - such situations do not arise.

Use of compression thermal pumps

By virtue of its high efficiency, this type of thermal pumps received almost widespread distribution, displacing all the others in various exotic areas. 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 one!

Evaporative absorption (diffusion) thermal pumps

Evaporative work cycle absorption heat pumps Extremely similar to the working cycle of evaporative compression settings, considered slightly higher. The main difference is that if in the previous case, the vacuum necessary for evaporation of the refrigerant is created in the mechanical suction of the vapor with a compressor, then in the absorption units, the evaporated refrigerant comes from the evaporator to the absorber block, where the absorbent is absorbed (absorbed) by another substance. Thus, the steam is removed from the volume of the evaporator and the vacuum is restored, ensuring evaporation of new portions of the refrigerant. Prerequisite It is the "affinity" of the refrigerant and the absorbent, so that the forces of their binding when absorbing were able to create a significant vacuum in the amount of evaporator. Historically, the first and still widely used pair of substances is ammonia NH3 (refrigerant) and water (absorbent). When absorbing the ammonia pair dissolve in water, penetrating (diffing) into its thickness. The alternative names of such heat pumps have occurred from this process - diffusion or absorption-diffusion.
In order to re-divide the refrigerant (ammonia) and the absorbent (water), which spent and rich in ammonia, the water-ammonium mixture is heated in the remover by an external source of thermal energy up to a boil, then somewhat cooled. Water is first condensed, but at high temperatures immediately after condensation, it is capable of holding very little ammonia, so the main part of ammonia remains as a pair. Here, under pressure, a liquid fraction (water) and gaseous (ammonia) are separated and separately cooled to ambient temperature. The cooled water with a small content of ammonia is sent to the absorber, and ammonia when cooled in the condenser becomes liquid and enters the evaporator. There the pressure drops, and ammonia evaporates, cooling the evaporator again and taking the heat from the outside. Then again couples ammonia couples with water, removing excess ammonia vapors from the evaporator and maintaining low pressure there. The solution enriched with ammonia again is sent to the desorber for separation. In principle, it is not necessary to boil the solution for desorption of ammonia, it is enough to heat it close to the boiling point, and the "extra" ammonia will disappear from the water. But boiling allows you to carry out the separation of the most quickly and efficiently. The quality of such a separation is the main condition determining the vacuum on the evaporator, and therefore it became, the efficiency of the absorption unit, and many tricks in the design are directed to this. As a result, according to the organization and number of stages of the working cycle, absorption-diffusion thermal pumps are perhaps the most complex of all common types of such equipment.

The "highlight" of the principle of work is that to generate a cold here is used to heat the working fluorescence (up to boiling). At the same time, the type of heating source is not sufficient, it may even be an open fire (burner flame), so the use of electricity is optional. To create the necessary pressure difference, which causes the movement of the working fluid, mechanical pumps can sometimes be used (usually in powerful installations for large volumes of working fluid), and sometimes, in particular in domestic refrigerators, elements without moving parts (thermosifones).

Absorption-diffusion refrigeration unit (ACH) fridge "Morozko-ZM". 1 - heat exchanger; 2 - collection of solution; 3 - hydrogen battery; 4 - absorber; 5 - regenerative gas heat exchanger; 6 - a deflectman ("Declaring"); 7 - condenser; 8 - evaporator; 9 - generator; 10 - Thermophone; 11 - regenerator; 12 - tubes of a weak solution; 13 - a steaming tube; 14 - electric heater; 15 - Thermal insulation.

The first absorption refrigeration machines (ABCHM) on the ammonium-water mixture appeared in the second half of the XIX century. In everyday life, because of the poisonousness of ammonia, they did not get much more common, but very widely used in the industry, providing cooling up to -45 ° C. In single-stage ABCM, the theoretically, the maximum cooling capacity is equal to the amount of heat spent on heating (actually, of course, noticeably less). It was this fact that reinforced the confidence of defenders of the very formulation of the second start of the thermodynamics, which was said at the beginning of this page. However, now the absorption heat pumps overcame this limitation. In the 1950s, more efficient two-stage (two capacitors or two absorber) bomistricular ABCHM (refrigerant - water, absorbent - LIBR lithium bromide) appeared. Three-step variants of ABCH are patented in 1985-1993. Their prototype samples are perfectly superior to two-stage by 30-50% and approaching mass models of compression settings.

Advantages of absorption heat pumps

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

The second advantage of these aggregates, especially valuable in domestic applications, is the ability to create structures that do not contain moving parts, and therefore almost silent (in the Soviet models of this type, it was sometimes possible to hear a quiet bouffaging or a lung hiss, but, of course, it does not go What comparison with the noise of the working compressor).

Finally, in household models, the working body (usually this is a water-ammonia mixture with the addition of hydrogen or helium) in the volumes used there are no greater danger for others even in case of emergency depressurization of the working part (this is accompanied by a very unpleasant zone, so not to notice a strong leakage It is impossible, and the room with the emergency unit will have to leave and ventilate "automatically"; the ultra-blank concentrations of ammonia are natural and absolutely harmless). In industrial installations, ammonia volumes are large and the concentration of ammonia during leaks can be deadly, but in any case, ammonia is environmentally friendly, it is considered that, unlike freon, 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 efficacy compared to compression.

The second drawback is the complexity of the design of the aggregate itself and a fairly high corrosion load from the working fluid, or requiring the use of expensive and hard-processed corrosion-resistant materials, or shortening the service life of the unit up to 5..7 years. As a result, the cost of "iron" is obtained noticeably higher than that of compression settings of the same performance (primarily it concerns powerful industrial aggregates).

Thirdly, many designs are very critical to the placement during installation - in particular, some models of household refrigerators demanded the installation strictly horizontally, and already with deviations for several degrees refused to work. The use of forced displacement of the working fluid by pumping greatly removes the sharpness of this problem, but approach the silent thermosifer and draining the self-ethone requires a very thorough alignment of the unit.

Unlike compression machines, absorption are not so afraid of too low temperatures - they are simply declining. But I was not at home put this paragraph into the deficiencies section, because it does not mean that they can work in a loddy stepmap - in the cold an aqueous solution of ammonia will be tritely overround in contrast to the freon compression machines, the freezing temperature 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 was not turned off all this time from the network, because there are no mechanical pumps and compressors in it, and the heating power in household models is enough to boil in the area The heater did not become too intense. However, all this depends on the characteristics of a particular design ...

Use of absorption heat pumps

Despite some less efficacy and relatively higher cost compared to compression plants, the use of absorption heat machines is absolutely justified where there is no electricity or where there are large volumetric volumes (spent pairs, hot exhaust or flue gases, etc. - right free heating). In particular, special models of refrigerators operating from gas burners, intended for motorists and yachtsmen travelers.

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

As experience shows, in everyday life are quite competitive and options with electrical heating, primarily in the range of small capacities - somewhere from 20 and to 100 W. Less power is the patrimony of thermoelectric elements, and with more thanks for more than the advantages of compression systems. In particular, among the Soviet and post-Soviet brands of refrigerators of this type were popular "Morozko", "North", "Crystal", Kiev with a typical volume of the refrigeration chamber from 30 to 140 liters, although there are models for 260 liters (" Crystal-12 "). By the way, assessing energy consumption, it is worth considering the fact that compression refrigerators almost always work in short periodic mode, and the absorption is usually included on a much longer period or work continuously. Therefore, even if the rated power of the heater will be much smaller than the capacity of the compressor, the ratio of the average daily energy consumption may be completely different.

Vortex heat pumps

Vortex heat pumps Used to separate the warm and cold air effect of the wound. The essence of the effect is that the gas, the tangentially supplied to the pipe at high speed, inside this pipe is twisted and separated: the chilled gas can be selected from the center of the pipe, and the periphery is heated. The same effect, although to a much lesser extent, acts for liquids.

Advantages of vortex heat pumps

The main advantage of this type of heat pumps is simplicity of construction and great performance. The vortex tube does not contain moving parts, and it provides it with high reliability and long service life. Vibration and position in space practically do not affect its work.

The powerful stream of air well prevents the frost, and the effectiveness of the vortex pipes weakly depends on the temperature of the input stream. The practical lack of fundamental temperature limitations associated with the supercooling, overheating or freezing of the working fluid.

In some cases, the ability to achieve a record high temperature separation on one stage plays its role: cooling numbers per 200 ° and more are given in the literature. Usually one stage cools air to 50..80 ° C.

Disadvantages of vortex heat pumps

Unfortunately, the effectiveness of these devices is currently visibly inferior to the effectiveness of evaporative compression installations. In addition, for efficient work, they require high feed rate of the working fluid. Maximum efficiency is noted at the speed of the input flow, equal to 40..50% of the speed of sound - this flow itself creates a lot of noise, and in addition, it requires a productive and powerful compressor - the device is also not a quiet and quite capricious.

The absence of the generally accepted theory of this phenomenon suitable for practical engineering use, makes the design of such aggregates, a lot of empirical, where the result depends greatly on luck: "Guess - did not guess." More or less reliable results gives only the reproduction of 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, currently the use of such devices is expanding. They are justified primarily where there is already gas under pressure, as well as on various fire and explosive industries - after all, to sue a dangerous zone, the air flow under pressure is often much safer and cheaper than pulling the protected wiring and put electric motors in a special design .

The limits of the effectiveness of thermal pumps

Why did heat pumps have not yet been widespread for heating (perhaps the only relatively common class of such devices is air conditioners with an inverter)? There are several reasons for this, and besides subjective, related to the lack of heating traditions with the help of this technology, there are also objective, the main among which is the frost of the heat selection and a relatively narrow temperature range for efficient operation.

In the vortex (primarily gas) installations of problems of hypothermia and frost, there is usually no. They do not use the change in the aggregate state of the working fluid, and the powerful air flow performs the functions of the NO Frost system. However, their effectiveness is much smaller than the evaporative heat pumps.

Supercooling

In the evaporative heat pumps, high efficiency is ensured due to the change in the aggregate state of the working fluid - transition from the liquid to gas and back. Accordingly, this process is possible in a relatively narrow temperature range. At too high temperatures, the working fluores will always remain gaseous, and with too low - it will evaporate with great difficulty or will hesitate. As a result, when leaving the temperature beyond the optimal range, the most energy-efficient phase transition becomes difficult or is excluded from the working cycle, and the efficiency of the compression installation is significantly falling, and if the refrigerant remains constantly liquid, then it will not work at all.

Frost

Selection of heat from the air

Even if the temperatures of all the thermal pump blocks remain at the necessary framework, during operation, the heat selection unit - the evaporator is always covered by moisture drops condensing from the surrounding air. But liquid water It flows from him by itself, not particularly preventing heat exchange. When the evaporator temperature becomes too low, the condensate drops freeze, and the newly condensing moisture immediately turns into an onee, which remains on the evaporator, gradually forming a thick snow "fur coat" - this is where it happens in the freezer of the ordinary refrigerator. As a result, the efficiency of heat exchange is significantly reduced, and then you have to stop working and dishonor the evaporator. As a rule, in the evaporator of the refrigerator, the temperature decreases by 25..50 ° C, and in the air conditioners due to their specificity, the temperature difference is less than 10..15 ° C. This becomes clear why most air conditioners fail to configure the temperature below +13 .. + 17 ° С - This threshold is installed by their constructors to avoid evaporator icing, because its thawing mode is usually not envisaged. This is one of the reasons why almost all air conditioners with an inverter mode do not work even with not very large negative temperatures - only at the very recently there were models designed to work with frosts up to 25 ° C. In most cases, already at -5 ..- 10 ° C, the energy costs for thawing are comparable to the amount of heat being uploaded from the street, and the heat transfer from the street is ineffective, especially if the humidity of the outdoor air is close to 100%, - then the external heat filter is covered with ice Especially quickly.

Selection of soil and water heat

In this regard, as a non-freeze source of "cold heat" for heat pumps, heat from earthly depletes is becoming more and wider. At the same time, it is understood by the non-preheated layers of the earth's crust, which are on multi-kilometer depth, and not even geothermal water sources (although, if lucky and they will be near, it would be foolish to neglect such a gift for fate). This is due to the "normal" heat layers of soil located at a depth of 5 to 50 meters. As you know, in middle lane The soil at such depths has a temperature of order + 5 ° C, which changes very little during the entire year. In more southern regions, this temperature can reach + 10 ° C and higher. Thus, the temperature difference between comfortable + 25 ° C and the soil around the heat selection is very stable and does not exceed 20 ° C, regardless of the frost outside the window (it should be noted that the temperature at the outlet of the heat pump is +50 .. + 60 ° C, but and temperature difference at 50 ° C is quite forces for heat pumps, including modern household refrigerators, calmly providing in the freezer -18 ° C at a temperature in the room above + 30 ° C).

Nevertheless, if you jump one compact, but a powerful heat exchanger, it is unlikely to succeed to achieve the desired effect. In fact, the heat selection in this case acts as an evaporator of the freezer, and if in a place where it is placed, there is no powerful inflow of heat (geothermal source or underground river), it will quickly freeze the surrounding soil, on what all the heat pumping will end. The solution may be the selection of heat from one point, but evenly with a large underground volume, however the cost of building a heat selection covering on a considerable depth of a thousand cubic meters of soil, most likely will make this solution absolutely unprofitable economically. Less costly option - drilling of several wells with an interval of several meters from each other, as was done in the experimental Moscow region "active house", but this is not noone else who did a well for water, can independently estimate the cost of creating geothermal Fields at least from a tens of 30 meter wells. In addition, the permanent selection of heat, albeit less strong than in the case of a compact heat exchanger, will still reduce the temperature of the soil around the heat collectors compared to the original. This will lead to a decrease in the efficiency of the heat pump during its long-term operation, and the period of stabilization of temperature at a new level may take several years during which heat extraction conditions will deteriorate. However, it is possible to try to partially compensate for the winter heat loss of it in reinforced by downloading to the depth of the summer heat. But not even given the additional costs of energy on this procedure, the benefits of it will not be too large - the heat capacity of the ground heat accumulator of reasonable sizes is quite limited, and it is clearly not enough for the whole Russian winter, although such a heat reserve is still better than nothing. In addition, the level, volume and speed of groundwater is very important here - abundantly moistened soil with a sufficiently high velocity of the flow of water will not allow the "stocks for winter" - the flowing water will carry the injected heat with it (even a meager movement of groundwater by 1 The meter per day in just a week will demolish the sparky heat aside by 7 meters, and it will be outside the working area of \u200b\u200bthe heat exchanger). True, the same waste of groundwater will reduce the degree of soil cooled in winter - new portions of water will bring new heat, and by them away from the heat exchanger. Therefore, if there is a deep lake, a big pond or river, never freezing to the bottom, then it is better not to dig a soil, but to put a relatively compact heat exchanger in the water - unlike the fixed soil, even in a non-inflexible pond or lake, free water convection is capable of providing much A more efficient heat supply to heat chipboard from a significant amount of reservoir. But here it is necessary to make sure that the heat exchanger does not oversee the heat exchanger to the water freezing point and it will not start closing the ice, since the difference between convection heat exchange in water and heat transfer is huge (at the same time, the thermal conductivity of the frozen and unlocked soil is often different not so much Strongly, an attempt to use the tremendous heat of the crystallization of water in the soil heat cell under certain conditions can justify itself).

Principle of operation of the geothermal heat pump Based on collecting heat from soil or water, and transfer to the system of heating the building. To collect heat, the non-freezing fluid flows through a pipe located in the soil or a reservoir near the building, to the heat pump. The heat pump, like a refrigerator, cools the liquid (selects heat), while the liquid is cooled at approximately 5 ° C. The liquid flows over the pipe in the outer ground or water, restores its temperature, and again goes to the thermal pump. The heat selected heat transfer is transmitted to the heating system and / or heated hot water.

It is possible to select heat in groundwater - underground water with a temperature of about 10 ° C is supplied from a well to a heat pump, which cools water to +1 ... + 2 ° C, and returns water under the ground. Thermal energy There is any subject with a temperature above the minus of two hundred seventy-three degrees Celsius - the so-called "absolute zero".

That is, the heat pump can take the heat from any item - land, reservoir, ice, rocks, etc. If the building, for example in the summer, needs to be cooled (conditioned), then the reverse process occurs - the heat is taken from the building and is reset to the ground (reservoir). The same heat pump can work in winter to heating, and in the summer to cool the building. Obviously, the heat pump can warm the water for hot domestic water supply, air-conditioning through fancoils, warm the pool, cool, such as ice rink, warm the roofs and tracks from ice ...
One equipment can perform all the functions on the heat and cooling of the building.