JP2989127B2 - Heat exchanger of absorption refrigeration system - 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 lithium bromide or the like as an absorbing solution.

[0002]

2. Description of the Related Art In an absorption refrigeration system, an aqueous solution (absorbing liquid) of lithium bromide or the like having a low concentration is heated and boiled by a high-temperature regenerator to form a solution (refrigerant) such as water and a medium-concentration absorbing liquid (absorbent). Medium concentration lithium bromide aqueous solution). Further, the refrigerant is re-evaporated from the medium-concentration absorbent in the low-temperature regenerator to generate a high-concentration absorbent. The refrigerant is liquefied in a condenser provided with a cooling coil, is supplied to an evaporator, and evaporates by removing heat of evaporation from the evaporation coil disposed in the evaporator. The high-concentration absorbing liquid is guided to an absorber provided with a cooling coil, absorbs the evaporated refrigerant after being dropped on the cooling coil, becomes a low-concentration absorbing liquid, and is returned to the high-temperature regenerator.

The low-concentration absorbent returning to the high-temperature regenerator has a low temperature, the high-concentration absorbent supplied to the absorber has a medium temperature, and the medium-concentration absorbent supplied to the low-temperature regenerator has a high temperature. I have. From the viewpoint of thermal efficiency, it is desirable that the absorption liquid having a low concentration be as high as possible and the absorption liquid having a high concentration be as low as possible. For this reason, the absorption refrigerating apparatus is provided with a heat exchanger for exchanging heat between the high-concentration or middle-concentration absorbent and the low-concentration absorbent.

[0004]

In the heat exchanger of this absorption refrigeration system, when the inlet of the high-concentration absorbent or the medium-concentration absorbent is below the outlet and the outlet is above, the lower the pressure, the higher the flow due to the head difference. . The outlet is connected to a low-temperature regenerator or an absorber, and the pressure decreases as the flow path itself goes downstream. For these reasons, as the water flows downstream in the heat exchanger, the pressure is reduced and the absorbing liquid evaporates, so that vapor lock easily occurs. When this vapor lock is generated in the heat exchanger, there is a problem that the heat exchange rate with the low concentration absorbent decreases. An object of the present invention is to prevent a high-concentration absorbing solution or a medium-concentration absorbing solution from decompressing and boiling in a heat exchanger, and a smooth flow and a reliable heat exchange in a liquid phase state in the heat exchanger can be achieved. It is an object of the present invention to provide a heat exchanger for an absorption refrigeration system.

[0005]

SUMMARY OF THE INVENTION The present invention provides a heating source,
A high-temperature regenerator having a heating tank for boiling the low-concentration absorbing liquid by the heating source to separate the refrigerant and the medium-concentration absorbing liquid, and a refrigerant recovery tank for recovering the evaporated refrigerant; A low-temperature regenerator that re-boils the absorbent and separates the refrigerant vapor and the high-concentration absorbent, a condenser that condenses the refrigerant generated by the high-temperature regenerator and the low-temperature regenerator, and evaporates the condensed refrigerant liquid. An evaporator that cools the cold and hot water for the cold heat source, and a refrigerator body that includes an absorber that absorbs the evaporated refrigerant vapor into the high-concentration absorbent,
The high-concentration absorbent produced by the low-temperature regenerator is passed through a high-concentration absorbent heat exchanger, and heat-exchanged with the low-concentration absorbent discharged from the absorber. The high-concentration absorbent heat exchanger, wherein the high-concentration absorbent heat exchanger has a structure in which a plate for separating each of the absorbent flow paths is laminated in a casing; The flow path has a high-concentration absorbent inlet at a lower part of the casing and a high-concentration absorbent outlet at an upper part, and the high-concentration absorbent outlet is provided for each high-concentration absorbent formed between the laminated plates in the casing. An outlet pipe with a throttle hole communicating with the liquid flow path is formed by penetrating substantially all the plates into the casing and inserting the outlet pipe.

According to a second aspect of the present invention, a heating source, a heating tank for boiling the low-concentration absorbing liquid by the heating source to separate the refrigerant into a medium-concentration absorbing liquid, and a refrigerant recovery tank for recovering the evaporated refrigerant A high-temperature regenerator having: a low-temperature regenerator that reboils the medium-concentration absorbent using the refrigerant recovery tank as a heat source to separate refrigerant vapor and a high-concentration absorbent, and is generated by the high-temperature regenerator and the low-temperature regenerator. Refrigerator body comprising a condenser for condensing the evaporated refrigerant, an evaporator for evaporating the condensed refrigerant liquid to cool the cold / hot water for a cold heat source, and an absorber for absorbing the evaporated refrigerant vapor into the high-concentration absorbent. After passing the high-concentration absorbent generated by the low-temperature regenerator through the high-concentration absorbent heat exchanger and exchanging heat with the low-concentration absorbent discharged from the absorber, the high-concentration absorbent is guided to the absorber. The concentration absorbing solution flow path, The concentration absorption solution in generated in the regenerator,
After passing through a medium-concentration absorbent heat exchanger and exchanging heat with the low-concentration absorbent discharged from the absorber, an absorption-type refrigeration apparatus having a medium-concentration absorbent flow path leading to the low-temperature regenerator, The intermediate-concentration absorbent heat exchanger has a structure in which a medium-concentration plate that separates each of the absorbent flow paths is stacked in a medium-concentration casing. A medium concentration absorbing liquid inlet is provided at a lower position, and a medium concentration absorbing liquid outlet is provided at a higher position, and the medium concentration absorbing liquid outlets are each medium concentration absorbing liquid passage formed between the stacked medium concentration plates in the medium concentration casing. An outlet pipe with a throttle hole communicating with the high-concentration absorbent is formed by penetrating substantially the entire medium-concentration plate into the medium-concentration casing, and the low-concentration absorbent discharged from the absorber is exchanged with the high-concentration absorbent heat exchange. Vessel and heat exchange of the above-mentioned medium concentration absorbent Intermediate concentration absorption solution and the high concentration absorption solution and heat-exchanged by, characterized in that a low concentration absorption solution flow path for feeding back into the high-temperature regenerator.

According to a third aspect of the present invention, the high-concentration absorbent heat exchanger and the middle-concentration absorbent heat exchanger are provided vertically in the same vertically long casing, and the low-concentration absorbent heat exchanger is provided vertically. The flow path has a low-concentration absorbent inlet at an upper end of the casing and a low-concentration absorbent outlet at a lower end and is formed along the entire length of the casing, and the middle-concentration absorbent flow path is formed at a lower end of the casing. A high-absorbance liquid inlet formed at a middle portion of the casing, and a high-absorbent liquid flow passage formed at a middle portion of the casing; It has a concentration absorption liquid outlet and is formed along the upper end from the middle of the casing.

According to a fourth aspect of the present invention, in the heat exchanger of the absorption refrigeration system, the throttle hole is formed by an axial slit formed in the outlet pipe. In the heat exchanger of the absorption refrigeration apparatus according to claim 5, the throttle hole is formed in an upper part of an outer peripheral surface of the outlet pipe.

[0009]

The heat exchanger of the absorption refrigeration system according to the present invention has a high-concentration absorbent outlet or a medium-concentration absorbent heat exchanger having a high-concentration absorbent outlet disposed above. Since the absorbent outlet is formed by an outlet pipe with a throttle hole communicating with each flow path in the casing, a decrease in the pressure of the high-concentration absorbent or the medium-concentration absorbent in the heat exchanger can be prevented.
As a result, it is possible to prevent the occurrence of vapor lock due to the reduced pressure of the absorbing liquid in the heat exchanger.

In the heat exchanger, a plurality of partitioned absorbent flow paths are formed between the stacked plates, and the flow rate of each of the absorbent flow paths is reduced by a throttle hole. For this reason, on the upstream side of the outlet pipe, the liquid state by the absorbing liquid is kept uniform in each of the absorbing liquid flow paths, and the drift is prevented.
As a result, a smooth flow of the absorbing liquid can be obtained, and the heat exchange efficiency with the low-concentration absorbing liquid can be improved.

According to the third aspect of the present invention, the high-concentration absorbent heat exchanger and the middle-concentration absorbent heat exchanger are integrated, so that the mounting property can be improved. According to the configuration of the fourth aspect, it is possible to easily form the throttle hole. According to the configuration of the fifth aspect, the effect of the throttle is easily uniformed in the length direction of the throttle hole, and the flow is uniform since the drift is strongly prevented, so that the heat exchange efficiency is greatly improved.

[0012]

1 to 3 show a heat exchanger H in which a high-concentration absorbent heat exchanger and a medium-concentration absorbent heat exchanger are integrated.
And is attached to the refrigerator main body 200 of the absorption refrigeration apparatus 100 shown in FIG. The refrigerator main body 200 has a vertical cylindrical shape, and the heat exchanger H has a vertically long and flat box shape,
It is vertically fastened to the outer wall surface of the refrigerator main body 200 and is housed on one side of the housing A. On the other side of the housing A, a cooling tower (cooling tower) CT and a cooling blower CB shown in FIG.

As shown in FIG. 5, the absorption refrigeration apparatus 100 includes a refrigerator main body 200 and a cooling tower (cooling tower).
An indoor unit CU is additionally provided to form a cooling / heating device. The absorption refrigeration apparatus 100 includes a high-temperature regenerator 1 for heating and boiling a low-concentration absorbent and separating it into a medium-concentration absorbent and refrigerant vapor.

The high-temperature regenerator 1 includes a heating tank 11 in which a gas burner B as a heating source is disposed below,
A medium-concentration absorbent partition 12 which is a cylinder extending upward from 1 and having an open upper end; and a refrigerant recovery tank 10 which is a vertical cylindrical container disposed on the outer periphery of the medium-concentration absorbent partition 12. .

In the medium-concentration absorbent partition 12, a medium-concentration absorbent having a medium concentration due to evaporation of the refrigerant is retained in a lower portion 121, and an absorbent (refrigerant vapor) boiled from an upper end opening 122.
Blows out into the refrigerant recovery tank 10. On the outer periphery of the refrigerant recovery tank 10, a low-temperature regenerator 2 having an effect of improving thermal efficiency is provided.

The low-temperature regenerator 2 has a vertical cylindrical shape and includes a low-temperature regenerator case 20 having a refrigerant vapor outlet 21 opened in the ceiling. In the low-temperature regenerator case 20, heat is passed from the lower part 121 of the intermediate-concentration absorbent partition 12 through the lower half of the heat exchanger H (intermediate-concentration absorbent heat exchanger part) by the intermediate-concentration absorbent flow path L1. The exchanged medium concentration absorption liquid is supplied. The medium concentration absorbing liquid is re-evaporated using the outer peripheral surface of the refrigerant recovery tank 10 as a heat source, and is separated into a high concentration absorbing liquid and refrigerant vapor.

On the outer periphery of the low-temperature regenerator 2, an airtight, vertical cylindrical evaporation / absorption case 30 is concentrically installed. An absorber 3 is provided in the evaporation / absorption case 30, and an evaporator 4 is provided on the outer periphery of the absorber 3. An airtight, vertical cylindrical condenser case 50 is installed concentrically on the outer periphery of the low-temperature regenerator 2 and above the evaporating / absorbing case 30, and a condenser 5 in which a cooling coil 51 is disposed.
Is provided.

The absorber 3 is provided with a cooling coil 31 wound in a vertical cylindrical shape inside an evaporating / absorbing case 30 and spraying the high-concentration absorbing liquid to the cooling coil 31 above the cooling coil 31. A high-concentration absorbent sprayer 32 is attached. The evaporator 4 has an evaporator coil 41 wound in a vertical cylindrical shape disposed on an outer portion inside the evaporator / absorber case 30, and a refrigerant liquid disperser 42 disposed above the evaporator coil 41.

A high-temperature regenerator 1, a low-temperature regenerator 2, an absorber 3,
The evaporator 4 and the condenser 5 are arranged concentrically and are integrally welded to form a vertical cylindrical refrigerator main body 200 as shown in FIG. The refrigerator main body 200 is
It is supported by the stand 201 and vertically erected inside the housing A.

Between the bottom of the absorber 3 and the bottom of the heating tank 11, the low-concentration absorbing liquid discharged from the absorber 3 is passed through the entire portion from the upper end to the lower end of the heat exchanger H. It is connected by a low-concentration absorbent flow path L2 for returning to the heating tank 11 of the high-temperature regenerator 1. Low concentration absorbent flow path L
2 is provided with an absorbent pump P1 for circulating a low concentration absorbent.

The upper part of the low-temperature regenerator 2 is a gas-liquid separator 22. The gas-liquid separator 22 is located between the upper part of the condenser 5 and the gap 5.
It communicates via A. The lower part 121 of the middle concentration absorbent partition 12 communicates with the top or bottom (the top in the figure) of the low temperature regenerator 2 through the middle concentration absorbent flow path L1.

A refrigerant liquid receiving portion 10a is provided between the refrigerant recovery tank 10 and the intermediate-concentration absorbing liquid partitioning tube 12, and communicates with the condenser 5 through a refrigerant flow path L3. The refrigerant liquid is sucked by the low pressure in the condenser case 50 and supplied to the condenser 5. A part of the refrigerant liquid flowing into the condenser 5 is vaporized by the low pressure, but the vaporized refrigerant is cooled and condensed by the cooling coil 51 together with the refrigerant of the low-temperature regenerator supplied from the gap 5A.

The high-concentration absorbent receiving section 23 of the low-temperature regenerator 2
Is connected to the high-concentration absorbent spraying device 32 of the absorber by a high-concentration absorbent flow path L4. The high-concentration absorbing liquid is sucked by the low pressure in the evaporation / absorption case 30 and passes through the upper half of the heat exchanger H (high-concentration absorbing liquid heat exchanger portion) to be heat-exchanged. 32.

The lower part of the condenser 5 and the evaporator coil 4 of the evaporator 4
The refrigerant liquid dispersing device 42 installed above the first liquid container 1 communicates with the refrigerant liquid supply passage L5. The refrigerant is sprayed on the surface of the evaporating coil 41 from the refrigerant liquid sprayer 42, evaporates by removing the heat of vaporization from the evaporating coil 41, cools cold and hot water as a heat medium flowing inside, and cools the refrigerant coil of the absorber 3. The high concentration absorbing liquid dropped from the high concentration absorbing liquid spraying tool 32 on the surface of 31 absorbs the liquid. Absorbing liquid that has become low concentration by absorbing refrigerant,
The heat is returned to the heating tank 11 by the low concentration absorbent flow path L2.

The cooling coil 31 is connected to the cooling coil 51, and further connected to the cooling tower CT via the cooling water circulation path 33. The cooling water is supplied by the cooling water pump P2 to the cooling tower CT → the cooling coil 31 → the cooling coil 51 → It circulates in the order of the cooling tower CT. The evaporating coil 41 is connected to the indoor unit CU through a cold / hot water circulation path 43 having a cold / hot water pump P3.

As shown in FIGS. 1 to 3, the heat exchanger H has a vertically elongated casing 6 having a rectangular cross section, and brackets 60, 60 welded to the side surfaces of the casing 6 are provided on the outer wall surface of the refrigerator main body 200. 202 is fastened with a fastener. The casing 6 is composed of a press-formed container body 61 and a lid 63 which is press-formed and has a fitting edge 62 provided around the outer periphery. The cover 63 is fitted into the main body 61 and the fitting surface is welded.

Inside the main body 61, a predetermined inlet opening 64a and an outlet opening 64b, which are press-formed, are provided with a high concentration absorbent flowing upward and a low concentration absorbent flowing downward.
A large number of plates 64 provided with irregularities 64c for partitioning the kind of absorbing liquid are fitted, and each plate 64, 64
An absorption liquid flow path is formed therebetween. In addition, while the formed absorbent flow path alternately flows the absorbent having different concentrations,
One of the flowing absorbents is different between the upper and lower portions in the main body 61.

That is, in the upper half of the main body 61, the high-concentration absorption liquid and the low-concentration absorption liquid flow, and in the lower half, the medium-concentration absorption liquid and the low-concentration absorption liquid flow. FIG. 1 shows details of the upper half of the heat exchanger H. The lid 63 has a low-concentration absorbent inlet 71 formed at the left corner of the upper end and a low-concentration absorbent outlet 72 at the right corner of the lower end. L2 is provided.

A medium-concentration absorbing liquid inlet 73 is provided on the left side of the lower end of the lid 63, and a medium-concentration absorbing liquid outlet 74 is provided on the right side of the intermediate part. A flow path L1 is provided. A high-concentration absorbent inlet 75 is formed on the left side of the middle part of the lid 63, and a high-concentration absorbent outlet 76 is formed on the right side of the upper end part. L4 is provided.

That is, in this embodiment, the casing 6
The upper half is a high-concentration absorbent heat exchanger, and the lower half is a medium-concentration absorbent heat exchanger. As in this embodiment, the configuration in which the heat exchange between the low-concentration absorbing solution, the medium-concentration absorbing solution and the high-concentration absorbing solution in one heat exchanger H is independent of each other.
There is an advantage that piping can be simplified as compared with the case where one heat exchanger is used.

FIG. 6 shows a change in temperature of the absorbing liquid that is heat-exchanged in the heat exchanger H. The low-temperature, low-concentration absorbent discharged from the absorber 3 is supplied to the heat exchanger H by the absorbent pump P1, and heat-exchanged with the high-concentration absorbent and the medium-concentration absorbent to be heated. It returns to 11 and is heated again and boils.

The medium-concentration absorbing liquid in the medium-concentration absorbing liquid separation tube 12 has a high temperature, and is exchanged with the low-concentration absorbing liquid in the heat exchanger H. After cooling, the medium is supplied to the low-temperature regenerator by a pressure difference. Is done. The high-concentration absorbent generated in the low-temperature regenerator 2 exchanges heat with the low-concentration absorbent in the heat exchanger H, is cooled, and is supplied to the high-concentration absorbent sprayer 32 with a pressure difference.

As shown in FIG. 1, the high-concentration absorbent outlet 76 has a slit 8 in the axial direction so as to communicate with each high-concentration absorbent flow path formed between the plates 64, 64 as a throttle hole.
An outlet pipe 8 provided with 1 is formed penetrating substantially all the plates 64.

The slit 81 serves as a throttle hole 82 for a number of high-concentration absorbent flow paths L4 provided in the heat exchanger H. The throttle hole 82 can prevent the pressure of the high-concentration absorbing solution or the medium-concentration absorbing solution in the heat exchanger from decreasing. As a result, it is possible to prevent the occurrence of vapor lock due to the reduced pressure in the heat exchanger. The same effect can be obtained by applying the present invention to the medium-concentration absorption liquid outlet 74 in the medium-concentration absorption liquid heat exchanger.

That is, when the medium-concentration absorbing liquid and the high-concentration absorbing liquid flowing by the pressure difference are formed in the heat exchanger H from the bottom to the top, the further the factor of the head difference is added, the more the downstream flows. It is easy to boil under reduced pressure. As in the present invention, the heat exchange rate can be further improved by maintaining the pressure on the upstream side of the outlet pipe 8 at a predetermined level or higher, preventing boiling due to reduced pressure, and retaining the absorbing liquid to maintain the liquid phase.

The slit 81 is formed at the upper end of the outlet pipe 8 so that the high-concentration absorbing liquid can be supplied to the high-concentration absorbing liquid outlet 76.
When flowing out from the outlet pipe, it passes through the side of the outlet pipe 8 and goes upward. For this reason, the effect of the throttle is easily uniformed in the length direction of the slit, and the flow becomes uniform, so that the heat exchange efficiency can be further improved. The throttle holes 82 may be a row of holes formed corresponding to the respective high-concentration absorbent flow paths L4 in the heat exchanger H. However, the use of the slits 81 reduces the processing labor. It should be noted that other heat sources such as an electric heater can be used as a heating source.

[Brief description of the drawings]

FIG. 1 is a sectional view of a heat exchanger.

FIG. 2 is a front view of the heat exchanger.

FIG. 3 is a side view of the heat exchanger.

FIG. 4 is a perspective view of an absorption refrigeration apparatus.

FIG. 5 is a configuration diagram of an absorption refrigeration apparatus.

FIG. 6 is a graph showing a heat exchange action by a heat exchanger.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 High temperature regenerator 2 Low temperature regenerator 3 Absorber 4 Evaporator 5 Condenser 6 Casing 8 Outlet pipe 10 Refrigerant recovery tank 11 Heating tank 64 Plate 71 Low concentration absorption liquid inlet 72 Low concentration absorption liquid outlet 73 Medium concentration absorption liquid inlet 74 Medium-concentration absorbent outlet 75 High-concentration absorbent inlet 76 High-concentration absorbent outlet 81 Slit 82 Restrictor hole 100 Absorption refrigeration system 200 Refrigerator body B Gas burner (heating source) H Heat exchanger L1 Medium-concentration absorbent flow path L2 Low Concentration absorption liquid flow path L4 High concentration absorption liquid flow path

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tsutomu Maruhashi 2-26, Fukuzumi-cho, Nakagawa-ku, Nagoya-shi Inside Rinnai Corporation (72) Inventor Satoshi Naito 916 Kuramatsucho, Hamamatsu-shi, Shizuoka Pref. (72) Inventor Norio Uenoden 4-1-2, Hirano-cho, Chuo-ku, Osaka City Inside Osaka Gas Co., Ltd. (72) Inventor Kaoru Watanabe 2-49, Numame, Isehara City, Kanagawa Prefecture, Japan 56) References JP-A-7-190650 (JP, A) JP-A-2-147766 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) F25B 15/00 303 F28F 3 / 08 311

Claims (5)

(57) [Claims] A high-temperature regenerator having a heating source, a heating tank for boiling the low-concentration absorbing liquid by the heating source to separate the refrigerant into a medium-concentration absorbing liquid, and a refrigerant recovery tank for recovering the evaporated refrigerant; A low-temperature regenerator that reboils the medium-concentration absorbent using the refrigerant recovery tank as a heat source to separate refrigerant vapor and a high-concentration absorbent, and a condenser that condenses the refrigerant generated by the high-temperature regenerator and the low-temperature regenerator An evaporator that evaporates the condensed refrigerant liquid to cool the cold / hot water for the cold heat source, and a refrigerator body that includes an absorber that absorbs the evaporated refrigerant vapor into the high-concentration absorbent, and the low-temperature regenerator. After passing the generated high-concentration absorbent through the high-concentration absorbent heat exchanger and exchanging heat with the low-concentration absorbent discharged from the absorber, a high-concentration absorbent flow path leading to the absorber is provided. In the absorption refrigeration system provided, The high-concentration absorbent heat exchanger has a structure in which plates for separating the respective absorbent flow paths are stacked in a casing, and the high-concentration absorbent flow path has a high-concentration absorbent liquid below the casing. The inlet has a high-concentration absorbent outlet on the upper side, and the high-concentration absorbent outlet is an outlet pipe with a throttle hole communicating with each high-concentration absorbent flow path formed between the laminated plates in the casing. An absorption refrigerating apparatus characterized by being formed by penetrating and inserting substantially all the plates into a casing. 2. A high-temperature regenerator having a heating source, a heating tank for boiling the low-concentration absorbing liquid by the heating source to separate the refrigerant into a medium-concentration absorbing liquid, and a refrigerant recovery tank for recovering the evaporated refrigerant. A low-temperature regenerator that reboils the medium-concentration absorbent using the refrigerant recovery tank as a heat source to separate refrigerant vapor and a high-concentration absorbent, and a condenser that condenses the refrigerant generated by the high-temperature regenerator and the low-temperature regenerator An evaporator that evaporates the condensed refrigerant liquid to cool the cold / hot water for the cold heat source, and a refrigerator body that includes an absorber that absorbs the evaporated refrigerant vapor into the high-concentration absorbent, and the low-temperature regenerator. After passing the generated high-concentration absorbent through a high-concentration absorbent heat exchanger and exchanging heat with the low-concentration absorbent discharged from the absorber, a high-concentration absorbent flow path leading to the absorber, Medium concentration generated by the high temperature regenerator An absorption type having a medium-concentration absorbent flow path which passes the collected liquid through a medium-concentration absorbent heat exchanger and exchanges heat with the low-concentration absorbent discharged from the absorber, and then leads to the low-temperature regenerator. In the refrigeration apparatus, the intermediate-concentration absorbent heat exchanger has a structure in which a medium-concentration plate that separates each of the absorbent flow paths is stacked in a medium-concentration casing. The medium-concentration casing has a medium-concentration absorption liquid inlet at a lower position, and a medium-concentration absorption liquid outlet at an upper position, and the medium-concentration absorption liquid outlet is formed between the medium concentration plates stacked in the medium-concentration casing. An outlet pipe with a throttle hole communicating with the absorbent flow path is formed by penetrating substantially all of the medium concentration plate into the medium concentration casing, and the low concentration absorption liquid discharged from the absorber is formed into the high concentration medium. Absorbent heat exchanger and medium concentration Intermediate concentration absorption solution by Osamueki heat exchanger and the high concentration absorption solution and heat exchange, absorption refrigerating apparatus is characterized in that a low concentration absorption solution flow path for feeding back into the high-temperature regenerator. 3. The low-concentration absorbent according to claim 1, wherein the high-concentration absorbent heat exchanger and the medium-concentration absorbent heat exchanger are provided vertically in the same vertically long casing. The flow path has a low-concentration absorbent inlet at an upper end of the casing and a low-concentration absorbent outlet at a lower end and is formed along the entire length of the casing, and the medium-concentration absorbent flow path is formed at a lower end of the casing. A concentration-absorbing liquid inlet, a medium-concentration absorbing liquid outlet in the middle, and formed along the middle from the lower end of the casing; the high-concentration absorbing liquid flow path has a high-concentration absorbing liquid inlet in the middle of the casing; An absorption refrigerating apparatus having a concentration absorbing liquid outlet and formed along the middle to the upper end of the casing. 4. The absorption refrigeration system according to claim 1, wherein the throttle hole is an axial slit formed in the outlet pipe. 5. The absorption refrigeration system according to claim 1, wherein the throttle hole is formed in an upper part of an outer peripheral surface of the outlet pipe.