JP3719490B2 - Absorption refrigeration system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an absorption refrigeration apparatus, and more particularly to an absorption refrigeration apparatus having a function of reducing and removing uncondensed hydrogen gas generated during an absorption refrigeration cycle operation.
[0002]
[Prior art]
Absorption refrigerators that are operated in an absorption refrigeration cycle have been known as cooling devices. However, in recent years, attention has been focused on advantages such as energy efficiency during operation. There is an increasing demand for absorption refrigerators that can also perform heat pump heating operation using the pumped heat. For example, Japanese Patent Publication No. 6-97127 proposes an absorption chiller / heater that can be operated in three modes of cooling operation, heating by heat pump operation, and heating by direct-fired (boiler) operation.
[0003]
In the absorption refrigeration cycle of the absorption refrigerator, a very small amount of non-condensable gas such as hydrogen gas is generated due to contact reaction between the components in the refrigerant and the metal material forming the refrigerant flow path and the corrosion inhibitor. . It is known that this non-condensable gas lowers the degree of vacuum of an absorber, an evaporator, etc., which are components that should maintain a low pressure environment of, for example, several mmHg to several hundred mmHg, and remarkably lowers the operating efficiency of air conditioning. . For this reason, the maintenance which discharge | releases this noncondensable gas out of an apparatus using extraction means, such as a vacuum pump, was needed for every fixed period.
[0004]
Japanese Patent Laid-Open Nos. 8-121911 and 5-9001 disclose devices for discharging non-condensable gas generated in an absorption refrigerator outside the apparatus. In these apparatuses, the non-condensable gas separated from the refrigerant liquid is guided to a heated palladium pipe, and the non-condensable gas is released into the atmosphere using the selective permeability of palladium.
[0005]
[Problems to be solved by the invention]
In an absorption refrigeration apparatus that uses an alcohol-based refrigerant such as fluorinated alcohol for the absorption refrigeration cycle, corrosion of the metal material forming the refrigerant flow path can be suppressed by mixing water in the refrigerant. Are known. In this case, since the mixed water reacts with aluminum forming the refrigerant flow path to generate a trace amount of hydrogen gas, it needs to be removed.
[0006]
Hydrogen gas is generated by the following anode reaction and cathode reaction. Anode reaction: Al → Al ³ + 3e ⁻ , Al ³ + 3OH → AlOOH · H ₂ O (hydration of aluminum ions (boehmite film formation)), cathode reaction: 3H + 3e → 3 / 2H ₂ (hydrogen generation).
[0007]
Not limited to alcohol-based refrigerants, a system using a combination of lithium bromide (LiBr) as an absorbent and water as a refrigerant, or a combination of ammonia (NH ₃ ) as a refrigerant and water as an absorbent is used. In this system, since hydrogen gas is generated from the water used, it is necessary to remove this hydrogen gas as well.
[0008]
According to the non-condensable gas discharge device disclosed in the above publication, the generated hydrogen gas is removed, but there are the following problems. In other words, in this non-condensable gas discharge device, the generated hydrogen gas is discharged outside the apparatus, so that the structure for maintaining the airtightness in the apparatus becomes complicated. In addition, in a system using an alcohol-based refrigerant, moisture contained in the refrigerant is gradually reduced, so that there is a problem that an appropriate amount of water necessary for suppressing corrosion cannot be secured.
[0009]
In view of the above problems, the present invention is an absorption refrigeration capable of removing generated non-condensable gas without lowering the degree of vacuum in the machine and maintaining an appropriate amount of moisture in the refrigerant. An object is to provide an apparatus.
[0010]
[Means for Solving the Problems]
The present invention for solving the above-described problems and achieving the object includes an evaporator containing a refrigerant, an absorber that absorbs refrigerant vapor generated in the evaporator with an absorbent solution, and an absorbent concentration of the solution. In order to recover the refrigerant, an absorption type having a regenerator for extracting the refrigerant vapor by heating the absorbent solution and a condenser for condensing the refrigerant vapor extracted by the regenerator and supplying the condensed refrigerant vapor to the evaporator The refrigeration apparatus is characterized in that a hydrogen gas removal apparatus mainly composed of metal oxide that brings about a reduction reaction in contact with hydrogen gas generated during the absorption refrigeration cycle operation is provided inside the condenser.
[0011]
According to this feature, the generated hydrogen gas comes into contact with the metal oxide to cause a reduction reaction, thereby generating water and removing the hydrogen gas. By removing the hydrogen gas in this way, it is possible to prevent a decrease in operating efficiency due to a decrease in the degree of vacuum of each part of the refrigerant passage such as a condenser, an evaporator, an absorber, etc., and the generated water returns from the hydrogen gas removal device to the refrigerant passage. Thus, the moisture in the refrigerant is maintained at an appropriate amount. In particular, since the hydrogen gas removing device is provided in the condenser, heat suitable for the reduction reaction can be obtained from the refrigerant vapor.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings. In the following description, the same reference numerals in the drawings refer to the same or equivalent parts. FIG. 7 is a system block diagram showing a main configuration of an absorption refrigerator according to an embodiment of the present invention. Here, an absorption type air conditioner is assumed as an embodiment of the absorption refrigerator. The evaporator 1 contains a fluorinated alcohol such as trifluoroethanol (TFE) as a refrigerant, and the absorber 2 contains a DMI derivative (dimethylimidazolidinone) as a solution containing an absorbent. The refrigerant is not limited to the fluorinated alcohol, but may be any one that can take a wide non-freezing range, and the absorbent solution is not limited to the DMI derivative and can take a wide non-crystalline range. The absorbent may be any absorbent that can absorb the refrigerant. In addition to the combination of the refrigerant and the absorbent solution, for example, lithium bromide (LiBr) is used as an absorbent, water is used as a refrigerant, or ammonia (NH ₃ ) is used as a refrigerant, and water is used as an absorbent. Matching can be used.
[0013]
The evaporator 1 and the absorber 2 are fluidly connected to each other via an evaporation (refrigerant) passage. When the evaporator 1 and the absorber 2 are held in a low-pressure environment of about 30 mmHg, for example, the evaporator 1 The refrigerant in the inside evaporates, and this refrigerant vapor enters the absorber 2 through the evaporation passage. In the absorber 2, the absorbent solution absorbs the refrigerant vapor and the absorption refrigeration operation is performed. The evaporating passage is provided with a precooler 18 that heats and vaporizes the mist (mist refrigerant) remaining in the refrigerant vapor and lowers the temperature of TFE fed from the condenser 9. Yes.
[0014]
When the burner 7 is ignited, the regenerator 3 increases the concentration of the solution in the absorber 2 (the burner, the regenerator, and the solution concentration will be described later). When the high-concentration solution in the absorber 2 absorbs the refrigerant vapor, the refrigerant in the evaporator 1 evaporates, and the inside of the evaporator 1 is cooled by the latent heat during the evaporation. A pipe line 1a through which cold water passes passes through the evaporator 1. As the cold water flowing through the pipe line 1a, it is preferable to use ethylene glycol or propylene glycol aqueous solution. One end (outlet end in the figure) of the pipe line 1a is connected to the # 1 opening of the first four-way valve V1, and the other end (inlet end in the figure) is connected to the # 1 opening of the second four-way valve V2.
[0015]
The refrigerant is guided to the spraying means 1b provided in the evaporator 1 by the pump P1, and sprayed onto the pipe line 1a through which the cold water passes. The refrigerant takes evaporative heat from the cold water in the pipe 1a to become refrigerant vapor, and the temperature of the cold water in the pipe 1a that has been deprived of heat by the refrigerant decreases. The refrigerant vapor flows into the absorber 2 through the evaporation passage. The refrigerant in the evaporator 1 is guided to the spraying means 1b, and a part thereof is also fed to the rectifier 6 through the filter 4. A flow control valve V5 is provided between the evaporator 1 and the filter 4.
[0016]
When the fluorinated alcohol vapor, that is, the refrigerant vapor is absorbed by the solution of the absorber 2, the temperature of the solution rises due to the heat of absorption. The absorption capacity of the solution is higher as the temperature of the solution is lower and as the solution concentration is higher. Therefore, in order to suppress the temperature rise of the solution, a pipe line 2a through which cooling water passes is provided inside the absorber 2. One end (outlet end in the figure) of the pipe line 2a passes through the condenser 9, and then passes to the # 2 opening of the first four-way valve V1 via the pump P3, and the other end (inlet end in the figure) of the pipe line 2a. Are respectively connected to the # 2 opening of the second four-way valve V2. The same aqueous solution as the cold water is used as the cooling water passing through the pipe line 2a.
[0017]
The solution is guided to the spraying means 2b provided in the absorber 2 by the pump P2, and sprayed onto the pipe line 2a. As a result, the solution is cooled by the cooling water passing through the pipe line 2a. On the other hand, since the cooling water absorbs heat, its temperature rises. When the solution in the absorber 2 absorbs the refrigerant vapor and the concentration of the absorbent decreases, the absorption capacity decreases. Thus, the refrigerant vapor is separated from the absorbent solution by the regenerator 3 and the rectifier 6 to increase the concentration of the solution and restore the absorption capacity.
[0018]
The solution diluted by absorbing the refrigerant vapor in the absorber 2, that is, the diluted solution, is guided to the spraying means 2b, and is fed to the rectifier 6 through the pipe 7b by the pump P2 and flows down to the regenerator 3. An open / close valve V3 is provided in the pipe line 7b connecting the pump P2 and the regenerator 3. The regenerator 3 is provided with a burner 7 for heating the dilute liquid supplied from the absorber 2. The burner 7 is preferably a gas burner, but may be any other type of heating means.
[0019]
The solution (concentrated liquid) heated by the regenerator 3 and having the concentration increased by extracting the refrigerant vapor is returned to the absorber 2 through the pipe line 7a. An on-off valve V4 is provided on the pipe line 7a. The concentrated liquid having a relatively high temperature is sprayed on the pipe line 2a by the spraying means 2c.
[0020]
When the dilute liquid fed to the regenerator 3 is heated by the burner 7, refrigerant vapor is generated. The absorbent solution mixed in the refrigerant vapor is separated by the rectifier 6, and the refrigerant vapor with higher purity is fed to the condenser 9. The refrigerant vapor is cooled by the condenser 9 to be condensed and liquefied, and returned to the evaporator 1 via the precooler 18 and the pressure reducing valve 11. This refrigerant is sprayed on the pipe line 1a.
[0021]
Although the purity of the vapor supplied from the condenser 9 to the evaporator 1 is extremely high, the absorbent component that is very slightly mixed in the refluxing refrigerant accumulates in a long operation cycle, and the inside of the evaporator 1 It is inevitable that the purity of the refrigerant gradually decreases. A small part of the refrigerant from the evaporator 1 is fed to the rectifier 6 through the filter 4 and is subjected to a cycle for raising the purity again together with the refrigerant vapor generated from the regenerator 3, thereby reducing the refrigerant purity. Is suppressed.
[0022]
The high temperature concentrated liquid in the pipe line 7a that has come out of the regenerator 3 is separated from the dilute liquid that has come out of the absorber 2 by a heat exchanger 12 provided in the middle of the pipe line that connects the absorber 2 and the rectifier 6. After being cooled by heat exchange, it is sprayed into the absorber 2. On the other hand, the dilute liquid preliminarily heated by the heat exchanger 12 is fed to the rectifier 6. In this way, the heat efficiency is improved. Furthermore, a heat exchanger (not shown) is used to transmit the heat of the concentrated liquid to be recirculated to the cooling water in the pipe 2a exiting from the absorber 2 or the condenser 9. 2), the temperature of the concentrated liquid refluxed to the absorber 2 may be further reduced, and the cooling water temperature may be further increased.
[0023]
The sensible heat exchanger 14 for exchanging heat between the cold water or the cooling water and the outside air is provided with a pipe line 4a, and the indoor unit 15 is provided with a pipe line 3a. One end (inlet in the figure) of each of the pipes 3a and 4a is opened to # 3 and # 4 of the first four-way valve V1, and the other end (outlet in the figure) is # 3 and # of the second four-way valve V2. The four openings are connected to each other. The indoor unit 15 is provided in a room that performs cooling and heating, and is provided with a fan for blowing cold air or hot air (both are common) 10 and an outlet (not shown). The sensible heat exchanger 14 is placed outside and the fan 19 forcibly exchanges heat with the outside air.
[0024]
The evaporator 1 is provided with a level sensor L1 that senses the amount of refrigerant, a temperature sensor T1 that senses the temperature of the refrigerant, and a pressure sensor PS1 that senses the pressure in the evaporator 1. The absorber 2 is provided with a level sensor L2 that senses the amount of the solution. The condenser 9 is provided with a level sensor L9 that senses the amount of the condensed refrigerant, a temperature sensor T9 that senses the temperature of the refrigerant, and a pressure sensor PS9 that senses the pressure in the condenser 9. The sensible heat exchanger 14, the regenerator 3, and the indoor unit 15 are provided with temperature sensors T14, T3, and T15, respectively. The temperature sensor T14 of the sensible heat exchanger 14 senses the outside air temperature, and the temperature sensor T15 of the indoor unit 15 senses the temperature of the room that is air-conditioned. The temperature sensor T3 of the regenerator 3 senses the temperature of the solution.
[0025]
In the above configuration, during the cooling operation, the first four-way valve V1 and the second four-way valve V2 are switched so that the respective # 1 and # 3 openings communicate with each other while the # 2 and # 4 openings communicate with each other. By this switching, the cold water sprayed with the refrigerant and lowered in temperature is guided to the pipe line 3a of the indoor unit 15 to cool the room.
[0026]
On the other hand, during the heating operation, the first four-way valve V1 and the second four-way valve V1 are switched so that the respective # 1 and # 4 openings communicate with each other and the # 2 and # 3 openings communicate with each other. By this switching, the warmed cooling water is guided to the pipe line 3a of the indoor unit 15, and the room is heated.
[0027]
If the outside air temperature becomes extremely low during the heating operation, it becomes difficult to pump heat from the outside air via the sensible heat exchanger 14, and the heating capacity is reduced. For such a case, a circulation passage 9a and an on-off valve 17 are provided to bypass between the condenser 9 and the regenerator 3 (or the rectifier 6). That is, when it is difficult to pump the heat from the outside air, the absorption refrigeration cycle operation is stopped, the steam generated in the regenerator 3 is circulated to and from the condenser 9, and the amount of heat generated by the burner 7 is increased in the condenser 9. In order to improve the heating capacity, the temperature of the cooling water is raised by a direct-fired operation that is efficiently conducted to the cooling water in the pipe 2a.
[0028]
Then, the hydrogen gas removal apparatus provided in the said air conditioning apparatus is demonstrated. FIG. 1 is a cross-sectional view of a condenser equipped with a hydrogen gas removal device. In the figure, the condenser 9 includes a casing 91, a core 92 installed in the casing 91, and a reducing unit, that is, a hydrogen gas removing device 93 provided adjacent to the core 92. On one end face of the casing 91, a refrigerant vapor receiving port 94 fed from the rectifier 6 is provided. The core 92 includes a plurality of plate members (fins) and a pipe 95 penetrating the fins, and the pipe 95 forms a part of the pipe 2a that is a cooling water passage.
[0029]
A hydrogen gas removing device 93 as a reducing unit is screwed into a tube 96 protruding from the upper part of the casing 9 into the condenser 9 and a screw part formed in an opening of a hole into which the tube 96 is inserted. It has a cap 97. The tube 96 is fixed to the casing 91 by screwing a cap 97 and the upper opening is closed. A mesh, that is, a filter (net) 98 is provided below the tube 96. The tube 96 whose bottom is covered with the filter 98 is filled with powdered or granular metal oxide 99.
[0030]
As the metal oxide 99, for example, a transition metal oxide simple substance or a mixture of transition metal oxides can be used. As an example, the main component of NiO alone or NiO,, can be used further _CuO, a mixture prepared by mixing MnO 2, _Al 2 _{O 3.} As another example, a mixture containing at least one of CuO, MnO ₂ , and Al ₂ O ₃ as a main component can be used.
[0031]
The hydrogen gas H ₂ generated by the absorption refrigeration cycle and stored in the condenser 9 comes into contact with the metal oxide 99 in the tube 96 through the filter 98. As a result, a reduction reaction of the metal oxide 99 occurs, and water is generated. Hydrogen gas is removed. That is, a chemical reaction according to the following formula (f1) occurs. MOX + XH ₂ = M + XH ₂ O (f1). Here, the symbol M is a transition metal, and X is a constant.
[0032]
Thus, since water is generated when the hydrogen gas accumulated in the condenser 9 is removed in contact with the metal oxide 99, the water content in the refrigerant flowing in the refrigerant passage is accompanied by the hydrogen gas removing action. There is no decrease. Accordingly, an appropriate amount of water mixed in the refrigerant is maintained in order to suppress corrosion of the metal material forming the refrigerant passage. Further, when lithium bromide or ammonia is used as a refrigerant, the absorbent solution combined with these is water, so even if H ₂ gas is removed and water is generated, the absorption refrigeration cycle is adversely affected. Of course, there is nothing.
[0033]
As shown in the figure, by installing a hydrogen gas removal device 93 at a position in the condenser 9 away from the refrigerant vapor inlet 94, the reduction in reaction efficiency due to the metal oxide 99 being wetted by the refrigerant is suppressed. Can do. This is because the condensation of the refrigerant vapor proceeds at a position far from the refrigerant vapor receiving port 94 and the adhesion is almost eliminated, and the surface of the metal oxide can be prevented from being covered with the film of the refrigerant liquid. .
[0034]
The hydrogen gas removing device 93 is not limited to being disposed at the position shown in FIG. FIG. 2 is a schematic view of the condenser 9 showing another installation example of the hydrogen gas removing device 93. In this example, a hydrogen gas removing device 93 is disposed on the refrigerant vapor receiving port 94 side. According to this arrangement, the hydrogen gas removing device 93 is exposed to the introduced refrigerant vapor having a relatively high temperature, and there is an advantage that the metal oxide 99 is maintained at a temperature suitable for the reduction.
[0035]
Next, a modification of the hydrogen gas removal device will be described. 3 is a cross-sectional view of a condenser 9 according to a first modification of the hydrogen gas removing device, and FIG. 4 is a view taken along the line AA of FIG. 3 and 4, the hydrogen gas removing device 100 is provided in the core 92. The hydrogen gas removing device 100 includes a shell portion 101 fixed to the outermost fin among a plurality of fins constituting the core 92, a filter 102 provided in an open portion below the shell portion 101, and a shell The metal oxide 99 is filled in a space surrounded by the part 101 and the filter 102. In the first modification, heat is directly propagated from the core 92 whose temperature is increased by the introduced refrigerant vapor to the shell portion 101 of the hydrogen gas removing device 100 and the metal oxide 99 held by the shell portion 101. As a result, the metal oxide 99 can stably receive the reduction promotion heat quantity from the core 92.
[0036]
FIG. 5 is a cross-sectional view of a condenser 9 including a second modification of the hydrogen gas removing device, and FIG. 6 is a view taken along the line BB in FIG. 5 and 6, hydrogen gas removing devices 103 are provided at two locations. The hydrogen gas removing device 103 is arranged so that the shell portion 104 surrounds the pipe 95 constituting a part of the pipe of the cooling water, in other words, the pipe 95 penetrates the shell portion 104. In the second modification, in addition to the temperature of the introduced refrigerant vapor, the shell portion 101 and the shell portion 101 of the hydrogen gas removing device 100 are heated by the heat propagated from the core 92 whose temperature is increased by the refrigerant vapor to the pipe 95. The held metal oxide 99 is held at an appropriate temperature.
[0037]
In the above-described embodiment, the powdered or granular metal oxide 99 is filled in the tube 96 or the shell portion 101, but the present invention is not limited to this. For example, a metal oxide layer may be formed on the outer periphery of the tube 96 or the shell portion 101 by sintering or the like, and hydrogen gas may be brought into contact with this layer. In this case, the filter 98 and the filter 102 are unnecessary, and the tube 96 and the shell portion 101 may be replaced with a solid rod or plate. The surface of the rod or plate forming the metal oxide layer may have a corrugated or uneven surface in order to increase the surface area. The metal oxide may be a simple substance listed above, or a substance having a catalytic action for promoting the reaction between the metal oxide and hydrogen gas, such as palladium or its compound (PdCl ₂ ), platinum or its compound, etc. A small amount of the additive may be mixed.
[0038]
As described above, in the absorption refrigerator according to the present embodiment, during operation, the hydrogen gas accumulated in the condenser 9 comes into contact with the metal oxide 99 in the hydrogen gas removal device, and water is generated by the reduction reaction. As a result, hydrogen gas is removed. This reduction reaction is promoted by the amount of heat of the high-temperature refrigerant vapor flowing from the rectifier.
[0039]
【The invention's effect】
As is apparent from the above description, according to the first to fifth aspects of the present invention, hydrogen generated in the cycle accompanying the operation of the absorption refrigeration apparatus is removed by a metal oxide reduction reaction, and water is generated. Accordingly, since the degree of vacuum of the refrigerant passage does not decrease, high operating efficiency can be maintained, and the generated water is not discharged outside the apparatus. For example, the moisture content of the refrigerant mixed with water is appropriately maintained. be able to.
[0040]
In addition, since the hydrogen gas removal device is provided in the condenser, a special seal structure is not required and the hydrogen gas removal device provided outside the condenser is connected to the condenser via a pipe line. The temperature of the refrigerant vapor introduced into the vessel can be used for the reduction reaction. In particular, according to the invention of claim 2, consideration is given to prevent the metal oxide of the hydrogen gas removing device from being wetted by the refrigerant vapor. . According to the invention of claim 3, the reaction efficiency can be increased by the high-temperature refrigerant vapor. According to the invention of claim 4, not only the temperature of the refrigerant vapor but also the temperature of the core plate exposed to the refrigerant vapor can be utilized. Furthermore, according to the invention of claim 5, not only the temperature of the refrigerant vapor but also the temperature of the cooling water pipe exposed to the refrigerant vapor can be utilized.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a main part of a condenser according to a first embodiment.
FIG. 2 is a schematic cross-sectional view of a condenser showing a modification of the first embodiment.
FIG. 3 is a cross-sectional view of a main part of a condenser according to a second embodiment.
4 is an AA arrow view of FIG. 3;
FIG. 5 is a main part configuration diagram of a condenser according to a third embodiment.
6 is a view taken along arrow BB in FIG. 5;
FIG. 7 is a system diagram showing a configuration of an absorption type air conditioner according to an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Evaporator, 2 ... Absorber, 3 ... Regenerator, 9 ... Condenser, 14 ... Sensible heat exchanger, 15 ... Indoor unit, 19 ... Fan, 91 ... Casing, 92 ... Core, 93, 100 ... Hydrogen gas Removal device, 94 ... refrigerant inlet, 95 ... cooling water pipe, 96 ... tube, 97 ... cap, 98, 102 ... filter, 99 ... metal oxide

Claims (5)

An evaporator containing a refrigerant, an absorber that absorbs the refrigerant vapor generated in the evaporator with an absorbent solution, and the refrigerant solution is extracted by heating the absorbent solution to restore the absorbent concentration of the solution. An absorption refrigeration apparatus having a regenerator and a condenser for condensing the refrigerant vapor extracted by the regenerator and supplying the condensed refrigerant vapor to the evaporator,
An absorption refrigeration apparatus comprising a hydrogen gas removal device mainly comprising a metal oxide that is brought into contact with hydrogen gas generated during an absorption refrigeration cycle operation to cause a reduction reaction inside the condenser. The condenser casing is provided with an inlet for receiving refrigerant vapor from the regenerator,
The absorption refrigeration apparatus according to claim 1, wherein the hydrogen gas removing device is provided near a surface facing the surface of the casing provided with the receiving port in the condenser. The condenser casing is provided with an inlet for receiving refrigerant vapor from the regenerator,
2. The absorption refrigeration apparatus according to claim 1, wherein the hydrogen gas removing device is provided close to a surface of the casing provided with the receiving port. The absorption refrigeration apparatus according to claim 1, wherein the condenser is provided with a core plate for condensing refrigerant vapor, and the hydrogen gas removing device is provided in close contact with the core plate. The condenser is provided with a core plate for condensing the refrigerant vapor and a cooling water pipe fixed to the core plate,
The absorption refrigeration apparatus according to claim 4, wherein the hydrogen gas removing device is provided in close contact with a pipe of the cooling water.

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