JP2806798B2 - Absorption refrigeration equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an absorption refrigeration system using an aqueous solution of ammonia, lithium bromide or the like as a working fluid.

[0002]

2. Description of the Related Art An absorption refrigeration system using an aqueous solution (working fluid) of ammonia, lithium bromide or the like generates vapor of a refrigerant such as ammonia by heating the aqueous solution with a generator, and decomposes the vapor of the refrigerant. The liquid is liquefied by a vessel, and is poured into a low-pressure evaporator via an expansion valve to perform a freezing operation. In the absorber, the refrigerant evaporated again by the evaporator supplies the working fluid diluted by the evaporation of the refrigerant as an absorbing liquid from the generator and absorbs the refrigerant in the absorber. The working fluid having a high concentration due to the absorption of the refrigerant (ammonia gas) is circulated to the generator by a pump.

[0003]

In this absorption refrigeration system, it is desired that the absorption refrigeration system be applied to a home air-conditioning / hot water supply system by increasing the load and miniaturizing the absorption refrigeration system. Use a burner as a source. If the calorific value of the burner is increased to increase the load, the generation of nitrogen oxides increases. In this case, it is effective to keep the combustion temperature of the burner low, and to achieve this, it is effective to increase the air-fuel ratio as much as possible and burn with a lean mixture. It is. An object of the present invention is to provide an absorption refrigeration apparatus that can reduce the generation of nitrogen oxides even when a high load operation is performed by increasing the calorific value of a burner with a small generator, and that can achieve high thermal efficiency.

[0004]

SUMMARY OF THE INVENTION An absorption refrigerating apparatus according to the present invention generates a mixed working liquid vapor of a refrigerant and an absorbing liquid by heating a working liquid in a heating vessel in which a refrigerant and an absorbing liquid are mixed by a burner. A generator, a rectifier for rectifying the mixed working liquid vapor to concentrate a refrigerant component, a condenser for condensing a gas refrigerant component of the concentrated mixed working liquid vapor, and a condenser for condensing the refrigerant gas. In an absorption refrigerating apparatus including an evaporator for evaporating a liquid refrigerant and an absorber for absorbing refrigerant vapor evaporated by the evaporator into a diluted working liquid, the burner includes a combustion plate, and an air introduction passage formed in an outer wall. And a burner housing for holding the combustion plate , and a fuel gun inserted into the burner housing .
Gas outlet for supplying air into the air introduction passage
A fuel gas supply means, an inner casing disposed in the burner housing surrounding the lower surface of the combustion plate and having an inner and outer communication port, and a short circuit for preventing a short circuit between the inner and outer communication port and the air introduction passage. A mixing channel is formed around the annular flow path between the inner casing and the burner housing from the air introduction passage to enter the inner casing from the inner / outer communication port.

[0005] In the configuration described in claim 2, the short-circuit preventing means is constituted by a partition wall provided between the inner casing and the burner housing. This partition wall is advantageously formed in one piece during the casting of the inner casing or the burner housing. In the configuration according to the third aspect, the air introduction passage is provided tangentially to a side wall of the burner housing, and the fuel gas supply unit is provided on a downstream side of a nozzle pipe attached in a direction crossing the air introduction passage. It was formed by a plurality of gas ejection holes arranged in a row.

[0006]

In the absorption refrigeration system, the burner
Burner from the air introduction passage provided on the outer wall of the housing
When the combustion air is supplied to the
Fuel gas is supplied from the ejection port. Therefore, the fuel gas
Gradually mixes with the combustion air while passing through the air introduction passage.
The combined to become a mixture, the gas mixture is passed around the annular flow passage provided between the inner casing and the burner housing, through a mixing channel that fall within the inner casing from the inside and outside communication port Bar
Supplied to Therefore, a long mixing channel can be formed by a compact burner, and the mixture can be sufficiently mixed, and the mixture can be preheated efficiently. As a result, it is possible to prevent the generation of a portion of a gas-rich mixture having a small air-fuel ratio, and to use a uniform and large mixture having a large air-fuel ratio, so that the combustion temperature can be reduced. The generation is reduced and the heat efficiency is improved by preheating the mixture. According to the configuration of the second aspect, a mixing channel having a long distance can be formed with a simple configuration. In the configuration of claim 3,
The fuel gas can be efficiently dispersed in the combustion air.

[0007]

8 and 9 show a cooling and heating water heater using an absorption refrigeration system 100 using an aqueous ammonia solution as a working fluid. The absorption refrigeration apparatus 100 of the present invention includes a generator 1 that generates ammonia gas, a heat source side heat exchanger 11 that acts as a decompressor during cooling operation, and acts as an evaporator during heating operation, and as an evaporator during cooling operation. Act,
During the heating operation, the liquid refrigerant and the gas refrigerant exchange heat between the use-side heat exchanger 3 and the use-side heat exchanger 3 having the use-side heat exchanger 3 acting as a decompressor and the absorber 4. An inter-refrigerant heat exchanger 2 is provided. Above the generator 1, a rectifier 12 and a decomposer (condenser) 13 are sequentially provided in an overlapping manner.

These devices are connected by a working fluid flow passage, and a working fluid flow passage connecting the decompressor (condenser) 13, the heat source side heat exchanger 11, the inter-refrigerant heat exchanger 2, and the use side heat exchanger 3. A first four-way switching valve 21 and a second four-way switching valve 22 for switching the flow path are interposed in the first and second passages. The inter-refrigerant heat exchanger 2 is a double-pipe heat exchanger composed of an inner pipe 2a and an outer pipe 2b. The inside of the inner pipe 2a is a passage exclusively used for liquid refrigerant, and the inside of the outer pipe 2b is used exclusively for gas refrigerant. Road.

The first four-way switching valve 21 allows the gas refrigerant from the generator 1 to flow into the heat source side heat exchanger 11 during the cooling operation, and absorbs the gas refrigerant from the outer pipe 2b of the inter-refrigerant heat exchanger. 4 During the heating operation, the operation is switched so that the gas refrigerant from the generator 1 flows into the use side heat exchanger 3 and the gas refrigerant from the heat source side heat exchanger 11 flows into the absorber 4 side. The second four-way switching valve 22 allows the gas refrigerant from the use side heat exchanger 3 to flow into the outer pipe 2b of the inter-refrigerant heat exchanger during the cooling operation, and
The gas refrigerant flows into the absorber 4 from b. At the time of heating operation, switching is performed so that the gas refrigerant from the generator 1 flows into the use side heat exchanger 3 and the outer pipe 2b of the inter-refrigerant heat exchanger.
The gas refrigerant from is flowed into the absorber 4.

The generator 1 includes a heating vessel 5 and a gas burner 6, as shown in FIGS. The heating container 5 boiles an ammonia aqueous solution (ammonia dilute solution), which is a dilute solution, by heating it to about 20 to 20 atm and about 200 ° C. to generate a mixed vapor of ammonia and water. The heating vessel 5 includes a vertical cylindrical body 51 which is entirely open at the top and communicates with a rectifier described later, and a bottom plate 52 welded to a lower portion of the cylindrical body 51.

The bottom plate 52 has a central spherical shell 5 bulging upward.
a, a cylindrical portion 5b extending downward from the outer periphery of the central spherical shell portion 5a, and a flange portion 5c extending outward from the lower end of the cylindrical portion 5b. Is a cylindrical body 51
Is welded to the lower inner peripheral wall. The central portion of the bottom plate 52 is formed in a spherical shell shape in order to withstand a high pressure in the heating vessel with a small thickness. At the center of the heating vessel 5, a dilute solution outlet pipe 20 for letting out the ammonia dilute solution and supplying it to the absorber 4 is inserted from the top to the bottom.

A combustion chamber 60 of the gas burner 6 is provided below the bottom plate 52, and a forced air type premixed combustion plate gas burner 6 of a forced blast type is mounted on the bottom of the combustion chamber 60. As shown in FIGS. 1 and 4 to 6, the gas burner 6 has a ceramic circular combustion plate 61 in which a large number of flame holes are formed in a predetermined pattern, and the combustion plate 61 is attached to the lower end of the cylindrical body 51. The apparatus includes a combustion plate holding frame 62 for attachment, and a burner housing 64 on which the combustion plate holding frame 62 is mounted.

The combustion plate holding frame 62 is provided with a cylindrical portion 6A for fitting the combustion plate at the center, and the outer periphery is a fastening edge 6B to a flange 57 provided on the lower end surface of the cylindrical body 51. The combustion plate 61 and a perforated plate 63 for uniformly distributing the air-fuel mixture are fitted into the combustion plate fitting cylindrical portion 6A, and the edge of the upper surface of the combustion plate 61 is held down by an annular bezel 6C. Above the combustion plate 61, an ignition electrode S and a misfire detection frame rod F are mounted so as to penetrate the cylindrical body 51.

The combustion plate holding frame 62 is a cylindrical container-shaped burner housing 6 serving also as a mixing pipe of combustion air and fuel gas.
4. The burner housing 64 is provided with a rectangular cylindrical air introduction passage 65 projecting in a tangential direction, and the air introduction passage 65 intersects with a gas nozzle pipe 67 in which a plurality of gas ejection holes 66 are arranged on the downstream side. Is plugged in. Combustion air is supplied to the air introduction passage 65 from the blower B, and fuel gas is supplied to the gas nozzle pipe 67 from the gas source G.

In the burner housing 64, a cup-shaped portion 82 closing the lower surface of the combustion plate 61 and having an upper opening 81 is provided.
And an inner / outer communication port 83 opened in a side wall of the cup-shaped portion 82.
An inner casing 8 having a vertical plate-like partition wall 84 protruding outward from an edge of the inner / outer communication port 83 is fitted. The partition wall 84 is in contact with one wall edge of the air introduction passage 65 on the side of the inside / outside communication port 83 to partition, and serves as short-circuit prevention means for preventing a short circuit between the air introduction passage 65 and the inside / outside communication port 83.

The burner housing 64 is formed by the partition wall 84.
Inside, an annular flow passage 90 extending from the air introduction passage 65 to the inside / outside communication port 83 is formed between the outer peripheral wall of the cup-shaped portion 82 and the inner peripheral wall of the burner housing 64. For this reason, in the burner housing 64, the air-fuel mixture supplied from the air introduction passage 65 goes around the annular flow path 90, enters the cup-shaped portion 82 from the inside / outside communication port 83, and passes through the perforated plate 63. Thus, a mixing channel 9 reaching the lower surface of the combustion plate 61 is formed.

The mixing channel 9 is longer than the annular channel 90 and occupies the entire internal volume of the burner housing 64, so that the volume is used to the maximum. Therefore, the premixed gas is sufficiently mixed, and the heat generated by the gas burner 6 is transmitted to the air / fuel mixture from the combustion plate 61, the combustion plate holding frame 62, the burner housing 64, and the inner casing 8, and the air / fuel mixture is efficiently preheated. Burner housing 64
It also cools itself.

The gas nozzle pipe 67 is connected to the air introducing passage 6.
5 and a plurality of gas ejection holes 66 are arranged in the gas nozzle pipe 67 toward the downstream side of the air introduction passage 65, so that the fuel gas is efficiently dispersed and injected into the combustion air. , And the premixing is sufficiently performed. As a result,
Partial low air-fuel ratio (gas-rich) parts are not generated, enabling combustion with a lean mixture with a uniform air-fuel ratio, reducing the generation of nitrogen oxides and improving thermal efficiency by preheating the mixture. I do. The increase in nitrogen oxides due to the pre-heating of the air-fuel mixture is almost negligible, and the effect of reducing the nitrogen oxides by promoting the mixing of the air-fuel mixture is extremely significant.

FIG. 7 shows measurement data of the air-fuel ratio and the generation of nitrogen oxides. (A) shows the case of the gas burner 6 having the short mixing channel without the annular flow channel 90, and (B) shows the case of the gas burner 6 having the mixing channel of the present invention. From this graph, it is clear that the higher the air-fuel ratio of the air-fuel mixture, the lower the generation of nitrogen oxides.
It can be seen that, since the thermal efficiency is improved, the generation of nitrogen oxides can be reduced even if the combustion is performed in a region where the air-fuel ratio is small. For this reason, the generation of nitrogen oxides can be maintained at a low level under the combustion conditions in which the excess air ratio is close to 1.0.

In this embodiment, the partition wall 84 as the short-circuit preventing means is integrally formed with the cup-shaped portion 82 by casting, and this method is the most economical.
May be integrally formed with the burner housing 64, or the partition wall may be formed separately and assembled. Further, the short-circuit preventing means may be a member having a structure other than a wall as long as a short-circuit between the air introduction passage 65 and the inside / outside communication port 83 can be prevented.

The outer periphery of the cylindrical portion 5b of the bottom plate and the cylindrical body 51
An annular space between the combustion chamber 60 and the inner periphery of the combustion chamber 60 is filled with a hydraulic fluid, and forms a water jacket 50 surrounding the outer periphery of the combustion chamber 60. This water jacket 5
Numeral 0 has the effect of reducing the heat dissipation loss of the combustion gas by covering the cylindrical body 51 and improving the thermal efficiency.

The central spherical shell 5a of the bottom plate 52 is provided with 32 lower holes 53, eight at regular intervals on four concentric circles. The upper side wall of the vertical cylindrical body 51 is provided with 32 upper holes 54, each having eight upper and lower holes at equal intervals in four upper and lower stages. As in this embodiment, by forming eight upper holes 54 at equal intervals in four upper and lower stages, the piping space can be made compact and the pipe diameter can be increased while maintaining the proper spacing between the pipes (the heat exchange area can be increased). Increase) is possible.

An outer cylinder 7 forming a cylindrical closed space 70 on the outer periphery of the heating vessel 5 is provided coaxially on the outer periphery of the heating vessel 5. The outer cylinder 7 includes a cylindrical body 71, an annular upper plate 72 closing an upper end thereof, and an annular lower plate 73 closing a lower end thereof, and a heat insulating material 74 is stretched on an inner peripheral wall of the cylindrical body 71. Cylinder 71
An exhaust hole 75 is formed at the lower end of the heat insulating material 74 and communicates with a lower end of a combustion gas retaining passage 77 described later provided in the cylindrical closed space 70, and an exhaust pipe 76 is provided to protrude in the horizontal direction. The exhaust port 75 is provided in the annular lower plate 73 and
6 may project downward.

An annular combustion gas retaining passage 77 is formed between the inner peripheral wall of the heat insulating material 74 and the outer peripheral wall of the heating vessel 5. Corrugated fins 56 as heat-absorbing fins are provided in the middle part of the outer peripheral wall of the heating vessel 5 by shifting the pitch by a half pitch in the vertical direction.
It is joined to the step by brazing or the like and located in the combustion gas retaining passage 77. Inside the heating vessel 5, 32 combustion gas flow pipes 55 bent in an inverted L-shape are vertically arranged in parallel. Each combustion gas passage pipe 55 has a lower end welded to the lower hole 53 and an upper end welded to the upper hole 54, and communicates between the combustion chamber 60 and the upper part of the combustion gas retention passage 77.

In the generator 1, the combustion gas generated by the all-primary combustion of the gas burner 6 flows from the combustion chamber 60 through the 32 combustion gas flow pipes 55 to the upper portion of the combustion gas retaining passage 77. The combustion gas entering the combustion gas retaining passage 77 descends while contacting the corrugated fin 56,
The gas is discharged from the exhaust hole 75 to the outside via the exhaust pipe 76. During this time, the heat generated by the gas burner 6 is transmitted to the internal working fluid via the bottom plate 52 of the heating vessel, and then heats the working fluid via the pipe wall of the combustion gas flow pipe 55, and the remaining heat energy Is absorbed by the corrugated fins 56 and the cylindrical body 51 and supplied to the working fluid. Thus, generator 1
Has a very large heat transfer area with a small size and a long contact time between the combustion gas and the heat transfer surface, so that the thermal efficiency can be increased up to about 80%. Therefore, high load operation can be performed with a small generator, and high refrigeration capacity can be obtained as a refrigeration system.

Next, the operation of the cooling and heating water heater will be described. When the working fluid in the heating vessel 5 of the generator 1 is heated by the gas burner 6, mixed steam of ammonia as a refrigerant and water as an absorbing solution is generated from the working fluid, and the mixed steam passes through the rectifier 12. Rise. In this rectifier 12,
Five-stage liquid storage shelves 1A to 1E are formed, and the working fluid (ammonia-concentrated solution) supplied from the absorber 4 to the generator 1 flows down from the upper liquid storage section to the lower liquid storage shelf sequentially.

In the rectifier 12, each time the mixed vapor of ammonia and water rising from below passes through each storage rack, the ammonia concentration in the mixed vapor is reduced by the temperature drop and the contact with the concentrated ammonia solution from above. Rises. And rectifier 1
The mixed vapor concentrated in 2 is further absorbed by the upper-stage decomposer 13, and water is condensed and separated to become about 99.8% ammonia gas.

[Cooling operation] As shown in FIG. 8, this gas refrigerant is supplied to the heat source side heat exchanger 11 acting as a decompressor through the first four-way switching valve 21 as shown by the arrow L. In the heat source-side heat exchanger 11, the air is cooled by the fan F to release heat of condensation and liquefy to become an ammonia liquid (liquid refrigerant). The liquid refrigerant passes through the inner tube 2a of the inter-refrigerant heat exchanger and is decompressed by the capillary tube 23 acting as a decompression mechanism, and then to the use-side heat exchanger (acting as an evaporator) 3 having a double-tube structure. Inflow.

The liquid refrigerant exchanges heat with the use-side heat medium (in this embodiment, water) supplied from the indoor unit in the use-side heat exchanger 3 through the use-side heat medium flow path 31 by driving the pump P1. And evaporates (water is cooled and becomes a cooling heat source), and becomes gas refrigerant again. This gas refrigerant is supplied to the second four-way switching valve 2
2 to the outer tube 2b of the inter-refrigerant heat exchanger, where the liquid refrigerant from the heat source side heat exchanger 11 (passes through the inner tube 2a)
After being pre-cooled and itself pre-heated, the first four-way switching valve 21
Then, it is supplied to the absorber 4 via the second four-way switching valve 22.

This gas refrigerant is again absorbed in the working fluid supplied from the generator 1 to the absorber 4 in the absorber 4. That is, the working fluid sprayer 42 is provided at the uppermost part in the absorber container 41 of the absorber 4.
As shown by the arrow L1, the working fluid (3% ammonia dilute solution) is supplied from the generator 1 through the capillary tube 24 which is cooled by the heat exchanger 26 in the rectifier and acts as a pressure reducing mechanism.

This ammonia dilute solution is sprayed from the sprayer 42 in the absorber vessel 41, absorbs the gas refrigerant supplied from the use side heat exchanger 3 into the absorber vessel 41, and is placed on the bottom of the absorber vessel 41. It falls into a certain liquid pool 43. The working fluid (ammonia concentrated solution) in the liquid reservoir 43 is pumped by a pump P2 as shown by arrows L2 and L3 in FIG. In the meantime, after the heat is exchanged and heated in the heat exchanger 25 of the separator 13 and the heat exchanger 44 in the absorber 4 for absorbing heat recovery, the uppermost storage shelf 1A in the rectifier 12 is heated. Supplied to

[Heating Operation] As shown in FIG. 9, the first four-way switching valve 21 and the second four-way switching valve 22 are switched, and the flow direction of the gas refrigerant (ammonia gas) flowing through the refrigeration circuit is switched. The gas refrigerant (concentration: 99.8%) generated by the decompressor 13 passes through the first four-way switching valve 21 and the second four-way switching valve 22 as shown by the arrow L4, and functions as a decomposer. The heat flows into the heat exchanger 3 and passes through the use-side heat medium flow path 31 to exchange heat with the use-side heat medium (in this embodiment, water) supplied from the indoor unit to condense. The water is thereby heated and becomes a heat source for heating in the indoor unit.

The refrigerant liquefied in the use side heat exchanger 3 is decompressed in the capillary tube 23 and then supplied to the heat source side heat exchanger 11 acting as an evaporator through the inner tube 2a of the inter-refrigerant heat exchanger. To evaporate, and further to the first four-way switching valve 2
1. It is supplied to the absorber 4 via the outer tube 2b of the inter-refrigerant heat exchanger and the second four-way switching valve 22. The generation, rectification, and condensation of the water-ammonia mixed vapor in the generator 1 and the like and the absorption of the ammonia gas refrigerant in the absorber are the same as in the cooling operation shown in FIG. The flow of the (ammonia concentrated solution and the ammonia dilute solution) is the same as in FIG.

In this embodiment, a heat exchanger 45 for a heat source such as hot water supply and a heat exchanger 46 for both cooling and heating are provided in the absorber 4 in addition to the heat exchanger 44 for recovering the absorbed heat. The heat exchanger 45 for a heat source such as hot water is provided in the hot water tank 1
4, a bath 15 and a bathroom dryer 16 connected via a pump P3 to form a hot water supply cycle using hot water as a heat medium.

A branch outward path 32 branched from the use-side heat medium flow path 31 at the outlet of the use-side heat exchanger 3 via the three-way switching valve V 1 is provided at the inlet side and the outlet side of the cooling / heating heat exchanger 46. , Branch return path 3 that joins the downstream side of the three-way switching valve V1
The three sides are connected to each other. The outlet side of the pump P4 in the cooling water flow path 35 connecting the heat radiating heat exchanger 34 and the pump P4 is connected to the branch outward path 32 via the three-way switching valve V2.
5 is a branch return path 3
3 is connected via a three-way switching valve V3.

As shown in FIG. 8, during the cooling operation, the three-way switching valves V2 and V3 are opened on the cooling water flow path 35 side, closed on the branch forward path 32 and the branch return path 33 side, and are turned on in FIG. As shown in FIG.
The side is closed and the branch outward path 32 and the branch return path 33 are opened. Therefore, during the cooling operation, the use-side heat medium is not supplied to the heat exchanger 46 in the combined cooling / heating absorber, the cooling water is supplied from the heat radiation heat exchanger 34, and the heat is supplied during the heating operation. The use side heat medium is supplied to the exchanger 46, and the cooling water from the heat radiation heat exchanger 34 is not supplied.

[Brief description of the drawings]

FIG. 1 is a front sectional view of a generator of an absorption refrigeration apparatus according to the present invention.

FIG. 2 is a perspective view of an upper portion of a heating container.

FIG. 3 is a sectional view taken along line AA of FIG. 1;

FIG. 4 is a sectional view taken along line BB of FIG. 1;

FIG. 5 is an assembly diagram of a gas burner.

FIG. 6 is a perspective view of a burner housing.

FIG. 7 is a graph showing data on the amount of generated nitrogen oxides of a gas burner.

FIG. 8 is a schematic configuration diagram of a cooling and heating device using an absorption refrigeration device.

FIG. 9 is a schematic configuration diagram of a cooling and heating device using an absorption refrigeration device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Generator 2 Heat exchanger between refrigerants 3 Use side heat exchanger 4 Absorber 5 Heating container 6 Gas burner 7 Outer cylinder 8 Inner casing 9 Mixing channel 11 Heat source side heat exchanger 12 Rectifier 13 Decompressor 61 Combustion plate 64 Burner housing 65 Air introduction passage 66 Gas outlet 67 Gas nozzle tube 75 Exhaust hole 77 Combustion gas retention passage 83 Inner / outer communication port 84 Partition wall (short circuit prevention means) 90 Annular flow path 100 Absorption refrigeration system G Gas source

Claims (3)

(57) [Claims] 1. A generator for heating a working fluid in a heating vessel in which a refrigerant and an absorbing fluid are mixed by a burner to generate a mixed working fluid vapor of the refrigerant and the absorbing fluid, and rectifying the mixed working fluid vapor. A condenser for condensing the refrigerant component, a condenser for condensing the gas refrigerant component of the concentrated mixed working liquid vapor, an evaporator for evaporating the liquid refrigerant condensed in the condenser, and an evaporator. In an absorption refrigeration system including an absorber for absorbing evaporated refrigerant vapor into a diluted working fluid, the burner includes a combustion plate, a burner housing having an air introduction passage provided on an outer wall and holding the combustion plate. For supplying fuel gas into the burner housing .
A fuel gas supply unit having a gas ejection port in the air introduction passage, an inner casing disposed in the burner housing around a lower surface of the combustion plate and having an inside / outside communication port, the inside / outside communication port, A short-circuit preventing means for preventing a short circuit with the air introduction passage; and a mixed flow passage that goes around the annular flow passage between the inner casing and the burner housing from the air introduction passage and enters the inner casing from the inside / outside communication port. An absorption type refrigeration apparatus characterized by forming: 2. The absorption refrigeration system according to claim 1, wherein the short-circuit preventing means is a partition wall provided between the inner casing and the burner housing. 3. The air inlet passage according to claim 1, wherein the air introduction passage is provided on a side wall of the inner casing in a tangential direction, and the fuel gas supply means includes a nozzle pipe attached in a direction crossing the air introduction passage. An absorption refrigeration apparatus comprising a plurality of gas ejection holes arranged in a row downstream of the nozzle tube.