WO2013164653A1

WO2013164653A1 - Method for cooling air and apparatus to perform the method

Info

Publication number: WO2013164653A1
Application number: PCT/HU2013/000037
Authority: WO
Inventors: Péter REMÉNYI
Original assignee: Remenyi Peter
Priority date: 2012-05-02
Filing date: 2013-04-29
Publication date: 2013-11-07

Abstract

The present invention is a method to reduce the temperature of air and if required for providing the required humidity of that (i. e. for air conditioning) and the apparatus to perform the method. The air is compressed in a compressor (2) with injection of water until to reach a supersaturated state, the liquid moisture component (water) is removed from the air through a moisture separator (7), the air is expanded in an expander (4), the liquid moisture component (water) is removed from the air through another moisture separator (8) and, if necessary, the air is compressed or passing through a choke (e.g. throttle valve (9)). The essential-features of the solution are that the air to be cooled is heated by compression and injected by water to reach a supersaturated state and the heat is extracted from the air by removing the hot moisture component (water).

Description

Method for cooling air and apparatus to perform the method

The present invention is a method to reduce air temperature and if required for providing the required humidity of that (i. e. for air conditioning) and apparatus to perform the method.

At the present time the air conditioning or air cooling processes are performed through the cooling of a refrigerant fluid which receives a portion of heat content of air in a heat exchanger. Such devices include two heat exchangers: one between air to be cooled and the refrigerant and the other between the refrigerant and the outside environment. The heat exchangers are expensive to manufacture, and corresponding intensity of heat exchange need a significant temperature difference between the mediums. In practice, this means that at the air side the refrigerant has to be cooled much more than the desired air temperature, at the output side the refrigerant has to be heated much higher than the temperature of the outside environment. It requires higher cooling capacity than is reasonable. This may cause unnecessary power consumption and icing or condensation in the heat exchanger.

Another problem is that the used refrigerants are harmful to the environment, so the disposal of such devices requires special care, and a leakage causes escaping refrigerant which damages the environment.

Therefore, I started dealing with air cooling technologies, in which the air to be cooled itself serves as a refrigerant in order to avoid the use of harmful refrigerants and the installation of the heat exchangers or at least the air-side heat exchanger with they mentioned disadvantages are not necessary.

Maybe the most well known air cooling method of this type is the evaporative cooling process. During this process, the evaporation of water sprayed into air to be cooled extracts the heat from the air. However, this process can only be used in warm and at the same time dry climate and the temperature decrease is very limited.

These limitations have attempted to be overcome by methods in which air is cooled by the cooling effect of its adiabatic expansion. Patent application DE 41 27 224 Al discloses a method in which the air to be cooled is compressed, then its moisture content is saturated in a scrubber, expanded and the deposited condensate is removed. The condensate removed is fed to the scrubber. The heat is extracted from the system through cooling of the scrubber.

Patent application WO 96/00368 Al discloses a combined heating/cooling thermal converter for central heating, air-conditioning, producing domestic hot water and food refrigeration, etc. An electric motor turns a compressor and a turbine and water is sprayed into the air passing to the compressor by a nozzle, ensuring saturation of the air by water. The air is heated during the compression process, before the humid air passes to a thermal mass-exchange column, where heat is released into 3 heat exchangers and the cooled air is passed along a pipe to the turbine, to reduce the power consumed by the motor. The air is then passed to a refrigerator.

In the air conditioning system of patent application US 3 967 466 A air is fed into a compressor, compressed, accompanied by a rise in temperature, cooled by a heat exchanger, and expanded back to substantially its initial pressure for discharge in the cold state at the expander outlet port. The main feature of this invention is means provided for spraying water into the air at the compressor inlet port to supersaturate the air. The droplets are evaporated during compression thereby absorbing heat of vaporization. As the compressed air is cooled in the heat exchanger, the excess additive water condenses, is collected in a sump, and recirculated back to the compressor inlet port.

One major drawback of these solutions is that the application of such scrubber, thermal mass-exchange column or heat exchanger with sump renders the apparatuses too robust to be used in homes or vehicles and too complex, therefore, expensive and inefficient. In addition, the humidity of the air having to be cooled is saturated, so they are not suitable for air-conditioning.

The present invention is directed, therefore, to a similar method for cooling air and apparatuses performing the method which use simple components and if it is required provides the desired level of air humidity as well. Another objective of the invention is to achieve other beneficial effects which increase the value for use of the method and the apparatuses, which improve them into a new quality category compared to the methods and apparatuses used nowadays.

I realized that air compression is appropriate to carry out at reduced temperatures and pressure with injecting water in order to reduce the compression energy requirements, and even worth the amount of water fed is preferable so much as the heat content of its portion which air is no longer able to absorb, is equal to the heat having to be extracted from air. Thus, the heat having to be extracted from air can be removed from the system through the removal of residual water easily, without the use of scrubbers or heat exchangers. Then, in an expansion step the saturated air can be cooled to a temperature at which its moisture retaining capacity equal to the desired absolute humidity at the desired temperature. So after removing condensed humidity and the air compressed or expanded to the desired final pressure, it has the desired humidity.

I realized also that water removed after expansion step is cool and substantially clean, therefore, it is suitable for injecting at compression thus I can improve the compactness of the devices operated by this method with recirculating the water removed after expansion step.

I realized also that after expansion during condensation, the molecules of condensing water surround the airborne particles (house dust, mites, pollen, microorganisms) as condensation nuclei, and this way they are removed from the air, producing a perfect air cleaning effect. This effect makes the method particularly advantageous to use in air conditioners, air cleaners, vacuum cleaners and

refrigerators.

Furthermore I realized that if the compression moves ahead until the injected water is completely evaporated and then in a first (pre-)expansion step, air is expanded to the first removal of the liquid moisture component (water), than the airborne particles can be separated from the air and removed from the main fluid flow of the process. Thus, at the second removal of liquid moisture component (water) we can get clear water, so feeding it back to the injection of the first compression step, deposits will not be formed in the system, therefore, such an apparatus does not require pre-treatment of water or removal of the contaminants even using simple tap water.

I realized that applying the invention in a refrigerator, the temperatures of any component of the refrigerator and the food stored in it are warmer or equal to air ih the internal space, which means frost will not form. This eliminates the need for regular defrosting.

I have solved the objective technical problem proposed to myself on the aforementioned findings by the methods characterized in claims 1-5 and apparatus for cooling air characterized in claims.6- 10. The specified steps of the methods are necessary, but beyond them may also include additional steps. Similarly, the

apparatuses may also contain additional features.

The "compression of air with injection of water" in this case means that the water is injected (sprayed) in before and/or during and/or after the compression. The "compressor having an injector" means that an injector is installed in the suction passage or the compression chamber or the discharge passage of the compressor. The "injector" means any device which is capable to feed liquid into a fluid.

The "supersaturated state" means that the relative humidity is more than 100 %, so liquid droplets are formed or remain in the humid air. In such case the partial pressure of water vapor in the air-water mixture is higher than the saturated vapor pressure of water-at the temperature of the air-water mixture. The "unsaturated state" means that the relative humidity is less than 100 %, so liquid droplets do not exist or evaporate in the humid air. In such case the partial pressure of water vapor in the air-water mixture is less than the saturated vapor pressure of water at the temperature of the air-water mixture.

/'Compressor" and "expander" means any machine or any part of a machine that is capable of compression or expansion'of a working fluid. The main novelty of my solution in comparison with known solutions is that the heat is not taken up by a cooled medium from air in a heat exchanger, but the air is brought to supersaturated state and the heat is extracted from the air by removing its hot liquid moisture component (water).

The solutions are presented with reference to drawings.

Figure 1 is the flowchart of a refrigerator according to the invention.

Figure 2 is the T-s (temperature-entropy) diagram of the states of water component during the working of refrigerator in Figure 1.

Figure 3 is the flowchart of the refrigerator in Figure 1 provided with a pre-expander. Figure 4 is the flowchart of the domestic hot water production version of the

refrigerator in Figure 1.

Figure 5 is the flowchart of an air conditioner according to the invention.

Figure 6 is the T-s diagram of the states of water component during working of the air conditioner in Figure 5.

Referring to Figure 1, a refrigerator is shown in accordance with the invention which is presented the simplest configuration so as to be as easy as possible to understand the process and the functioning of the apparatus. Figure 2 illustrates the state changes of the water component of air working fluid in the system shown in Figure 1. The correspondence of a given location of the system and the current state of the water component at the given location is shown by letters in Figures 1 and 2.

Because of the heat transfer between water and air components of the working fluid, the adiabatic changes of the working fluid are not adiabatic in respect to the water component, therefore, no vertical lines correspond to adiabatic state changes of the working fluid. To emphasize the nature of state changes and to have a better view of them, the diagram is slightly distorted, so it is not fully proportional. The refrigerator cools 1 cooled space. The apparatus has a 2 compressor and a 4 expander mounted on a common axis drawn by a 5 electric motor. A 6 mixing chamber with an injector is installed at the inlet of 2 compressor for injecting water into the air sucked. Between 2 and 4 compressors and at the outlet of 4 expander 7 and 8 moisture separators (traps) are installed. Air flown from 8 moisture separator is fed back to 1 cooled space via a 9 throttle valve.

The 7 and 8 moisture separators can be provided with units to facilitate condensation such as ultrasonic atomizing or pressure waves generating equipments which are not shown in Figure 1. The condensate (water) outlet of 7 moisture separator is connected to a 10 heat exchanger, from which the cooled water is fed to an 11 condensate container. To the bottom of that a drain valve is connected to remove the solid particles and the dispensable water. The condensate (water) coming from the outlet of 8 moisture separator is fed to 6 mixing chamber by a 12 pump. The water contained in 11 condensate container is drawn here also.

In an exemplary operating cycle of the apparatus 2 compressor sucks 8 °C and 70 % relative humidity air from 1 cooled space to which water is injected in 6 mixing chamber. This moist air is compressed in 2 compressor to 2.2 bar, reaching a temperature of 80 °C and relative humidity of 150 %. The moisture content above the saturation level is constituted by the unevaporated part of water droplets injected whose temperature corresponds to that of the air component. Said droplets are removed in 7 moisture separator. The air saturated this way is expanded to 1.1 bar in 4 expander. This 4.05 °C air which has approx. 3000 % relative humidity is fed to 8 moisture separator. After the condensed moisture content above the saturation level removed there, it passes through 9 throttle valve so its temperature is reduced to 4 °C and its relative humidity will be 90%.

The 80 °C water leaving 7 moisture separator is cooled in 10 heat exchanger and gets to 11 condensate container. Cooling could be done by heat transfer to the environment or by heating domestic hot water. The airborne particles which get into the condensate during condensation, settle on the bottom of 11 condensate container. The 4.05 °C water, leaving 8 moisture separator, is injected into 6 mixing chamber and if necessary supplemented by water stored in 11 condensate container. The dispensable water is regularly drained from 11 condensate container together with deposited solid particles.

The apparatus is controlled by change the speed of 5 electric motor, feeding water to 6 mixing chamber, 9 throttle valve and the rates of compression and expansion.

If the relative humidity of the air in 1 cooled space is not necessary to keep below the saturation level, the throttle valve 9 may be omitted. Then the apparatus is simplified further.

In the preferred embodiment shown in Figure 3 of apparatus of Figure 1, a 3 pre-expander is installed between 2 compressor and 7 moisture separator and water injection has moved behind 2 compressor. This apparatus should be operated so that 2 compressor compresses the intake air to a pressure and temperature in which the injected water is able to evaporate completely. Thus, in the subsequent pre-expansion the condensation starts around airborne particles as condensation nuclei. Then all particles are surrounded by water and removed in the step of removing liquid moisture component. Because of the higher temperatures, all microorganisms surrounded by water are sterilized.

In another preferred embodiment shown in Figure 4 of apparatus of Figure 1, the condensed water leaving 7 moisture separator is collected and used as domestic hot water. In this case tap water is added to the water leaving 8 moisture separator for injecting into 6 mixing chamber as required. The condensate (water) leaving 7 moisture separator contains only minimal amounts of dust particles, therefore, hot water produced is appropriate for personal hygiene. This embodiment does not contain any heat exchanger.

Referring to Figure 5, a complex air conditioner is shown in accordance with the invention, in which the individual components are integrated together as far as possible to obtain a compact apparatus. The air conditioner serves to cool a 21 room. The apparatus has a 33 compressor unit and a 34 expander unit mounted on a common axis drawn by a 25 electric motor. The 33 compressor unit has 22 and 29 compressors, the 34 expander unit has a 23 pre-expander and a 24 expander. A nozzle is installed in 22 compressor for injecting water into its working chamber. Between 23 pre-expander and 24 expander and at the outlet of 24 expander 27 and 28 moisture separators are installed. Air flown from 28 moisture separator is drawn to 29 compressor then is fed back to 21 room.

The 27 and 28 moisture separators are provided with ultrasonic atomizing equipments to facilitate condensation. The condensate (water) outlet of 27 moisture separator is connected to a 30 heat exchanger, from which the cooled water is fed to a 31 condensate container. To the bottom of that, a drain valve is connected to remove the solid particles and the dispensable water. The water coming from the outlet of 28 moisture separator is fed to 22 compressor by a 32 pump. The water contained in 31 condensate container is drawn here also.

In an exemplary operating cycle of the apparatus, 22 compressor of 33 compressor unite sucks 23 °C and 70 % relative humidity air from 21 room which is compressed to 2 bar with water injecting reaching the temperature of 94 °C. This air is expanded in 23 pre-expander to 1.4 bar and cooled to 80 °C. Its relative humidity is approx. 115 %, from which the moisture content above the saturation level is removed in 27 moisture separator. The air saturated this way is expanded to 0.65 bar in 24 expander. The 4.6 °C air which has approx. 3000 % relative humidity is drawn to 28 moisture separator. After the condensed moisture content above the saturation level has removed there, its temperature rises to 19 °C and its relative humidity will be 60 %. . ^' -

, The 80 °C condensate (water) leaving 27 moisture separator is cooled in 30 heat exchanger and get to 31 condensate container. The particles that got into the condensate during condensation settle on the bottom of 31 condensate container. The 4.6 °C condensate (water), leaving 28 moisture separator injected into the working chamber of 22 compressor and if necessary supplemented by the water stored in 31 condensate container.

The T-s diagram in Figure 6 illustrates the mentioned state changes of water component of the air working fluid in the system. To emphasize the nature of state changes and to better view of them, the diagram is slightly distorted, so it is not fully proportional. The correspondence of a given location of the system and the current state of the water component at the given location is shown by letters.

The apparatus is controlled by change of speed of 25 electric motor, feeding' water to working chamber of 22 compressor and the rates of compression and expansion.

Connecting a vacuum hose to the air outlet of 21 room (preferably interposing a cyclone dust separator), the apparatus can also be used for vacuum- cleaning. In this mode, condensate (water) leaving 27 moisture separator is preferably drawn to drain and tap water is feeding for injection.

In a preferred embodiment of this apparatus, the condensed water leaving 27 moisture separator is drawn directly to 31 condensate container and mixed with tap water to produce domestic hot water. In this case, tap water is added to the water leaving 28 moisture separator for injecting as required. The condensate (water) leaving 27 moisture separator contains only minimal amounts of dust, therefore, hot water produced is appropriate for personal hygiene. This solution does not contain any heat exchanger.

The available formulas describe the states and the state changes of ideal gases so for wet and near-saturated gases give only inaccurate results. Consequently, the specified state indicators of the processes above could be inaccurate, but these inaccurate values are suitable to illustrate the order of magnitude of values. In the course of the implementation of these processes and systems the experimental determination and exact settings of said values are unavoidable, but they are routine actions in the art.

Claims

1. Method for cooling air with compression, injection of water and expansion, comprising the steps of

1.1. compression of air with injection of water,

1.2. until to reach a supersaturated state,

1.3. removing the liquid moisture component (water) from the air,

1.4. expansion of the air,

1.5. removing the liquid moisture component (water) from the air.

2. Method according to claim 1, wherein the step 1.5 followed by step of

1.6. compression or passing through a choke the air.

3. Method according to claims 1 or 2, wherein in said step 1.1 compression with injection is continued until to reach an unsaturated state and then expanding.

4. Method according to claims 1 or 2, wherein the water removed in step 1.5 is injected at least partially in step 1.1.

5. Method according to claim 4, wherein the water obtained in step 1.3 is cooled, settled and the sludge is removed if necessary, the clean water is used in step 1.1.

6. Apparatus for cooling air including a compressor (2,22) having an injector and connected with a space to be cooled and an expander (4,24), characterized by the outlet of the compressor (2,22) connected with a moisture separator (7,27), the expander (4,24) and another moisture separator (8,28) one after another; the outlet of the moisture separator (8,28) connected with the space to be cooled.

7. Apparatus according to claim 6 characterized by another compressor (29) or a throttle valve (9) interposed between the outlet of the moisture separator (8,28) and the space to be cooled.

8. Apparatus according to claim 6 or 7, characterized by the water outlet of the moisture separator (8,28) connected with the injector by interposing a pump (12,32).

9. Apparatus according to claim 6 or 7, characterized in that comprising a pre-expander (3,23) interposed between the compressor (2,22) and the moisture separator (7,27).

10. Apparatus according to claim 6 or 7, characterized by having a connector in the space to be cooled where compressor (22) connected with that to enable connection - optionally interposing a dust separator - of a vacuum hose.