JP2019138606A - Absorption type freezer - Google Patents

Abstract

To provide an absorption type freezer capable of improving COP.SOLUTION: An absorption type freezer includes: a booster 12a boosting absorption liquid absorbing refrigerant by an absorber 11 toward a regenerator 13; a positive displacement type power recovery machine 12c recovering power from the absorption liquid going toward the absorber 11 from the regenerator 13 and driving the booster 12a using the recovered power; a supply passage 42 for supplying part of the gaseous refrigerant separated from the absorption liquid and going toward the condenser 22 to the power recovery machine 12c; and an absorption liquid heat exchanger 17 performing heat exchange between the absorption liquid going toward the regenerator 13 from the booster 12a and the absorption liquid going toward the absorber 11 from the power recovery machine 12c.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an absorption refrigeration apparatus that utilizes absorption of a refrigerant into an absorption liquid and release of the refrigerant from the absorption liquid.

  Conventionally, an absorption refrigeration cycle using absorption of a refrigerant into an absorption liquid and discharge of the refrigerant from the absorption liquid is known. For example, Patent Document 1 discloses a compression heat pump cycle (compression refrigeration cycle) that uses a shaft output of a prime mover as a power source for a compressor that compresses a refrigerant, and a regenerator that heats an absorption liquid from exhaust heat of the prime mover. An exhaust heat utilization heat pump system including an absorption heat pump cycle (absorption refrigeration cycle) that is used as a heat source is disclosed.

JP 2010-96429 A

However, when a refrigerant used under high pressure such as carbon dioxide (CO ₂ ) is employed in the absorption refrigeration cycle, the differential pressure between the absorber and the regenerator increases. For this reason, the power of the pump that circulates the absorbing liquid between the absorber and the regenerator increases, and the COP (Coefficient of Performance) of the absorption refrigeration cycle decreases accordingly.

  This invention is made | formed in order to solve such a subject, and it aims at providing the absorption refrigeration apparatus which can improve COP.

  In order to achieve the above object, the absorption refrigeration apparatus of the present invention includes a booster that boosts the absorption liquid that has absorbed the refrigerant in the absorber toward the regenerator, and the absorption that is directed from the regenerator to the absorber. Recovering power from the liquid, using the recovered power to drive the booster, and a part of the gaseous refrigerant separated from the absorbing liquid and directed to the condenser, A supply path that supplies power to the power recovery machine, a heat exchanger that exchanges heat between the absorption liquid that travels from the booster to the regenerator and the absorption liquid that travels from the power recovery machine to the absorber.

  According to the present invention, the COP of the absorption refrigeration apparatus can be improved.

The figure which shows the outline | summary of the absorption refrigeration apparatus which concerns on embodiment of this invention.

  Hereinafter, an absorption refrigeration apparatus according to an embodiment of the present invention will be described with reference to the drawings. The following embodiments are merely examples, and do not exclude various modifications and technical applications that are not explicitly described in the following embodiments. In addition, each configuration of the present embodiment can be implemented with various modifications without departing from the spirit thereof. Furthermore, each structure of this Embodiment can be selected as needed, or can be combined suitably.

[1. Outline of absorption refrigeration system]
The outline of the absorption refrigeration apparatus according to the embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a diagram showing an outline of an absorption refrigeration apparatus 1 according to an embodiment of the present invention. The absorption refrigeration apparatus 1 of the present embodiment is a refrigeration apparatus that uses a compression absorption hybrid cycle. That is, the absorption refrigeration apparatus 1 absorbs a gaseous refrigerant (hereinafter also referred to as “refrigerant gas”) in a low-temperature and low-pressure absorption liquid and performs heat exchange, and then separates the absorption liquid from the refrigerant gas. The circuit 10 and a compression refrigeration circuit 20 that uses heat radiation when condensing the refrigerant that has been compressed to high temperature and pressure are included. Moreover, in the absorption refrigeration apparatus 1 according to the present embodiment, carbon dioxide CO ₂ is used as a refrigerant.

  The absorption refrigeration circuit 10 includes an absorber 11, a regenerator 13, a gas-liquid separation tank 14, a flow rate adjustment valve 15, and an absorption liquid heat exchanger 17. The absorber 11 and the regenerator 13 are connected by a concentrated absorption liquid pipe 31 indicated by a thick broken line and a rare absorption liquid pipe 32 indicated by a thin broken line. In the middle of the concentrated absorbent liquid pipe 31, the circulation pump 12 and the absorbent liquid heat exchanger 17 are arranged in this order from the absorber 11 toward the regenerator 13. In the middle of the rare absorption liquid pipe 32, the gas-liquid separation tank 14, the circulation pump 12, and the absorption liquid heat exchanger 17 are arranged in this order from the regenerator 13 toward the absorber 11.

  Further, the rare absorption liquid pipe 32 is provided with a bypass pipe 32a that bypasses the circulation pump 12, and the flow rate adjusting valve 15 is disposed in the middle of the bypass pipe 32a. The bypass pipe 32a and the flow rate adjustment valve 15 will be further described later.

  The circulation pump 12 is for circulating the absorption liquid. By operating the circulation pump 12, the concentrated absorbent (absorbed liquid that has absorbed the refrigerant) in the concentrated absorbent pipe 31 is supplied from the absorber 11 to the regenerator 13 and the rare absorbent in the rare absorbent pipe 32. (Absorption liquid from which the refrigerant has been separated) is supplied from the regenerator 13 to the absorber 11. The circulation pump 12 is a positive displacement rotary pump and integrally includes a power recovery machine 12c. Specifically, the circulation pump 12 includes an absorption liquid pump (a pressure increasing device) 12a that pressurizes and pumps the absorption liquid by a rotating body, and an electric motor (hereinafter referred to as “motor”) that drives the rotating body of the absorption liquid pump 12a. 12b, and a positive displacement type power recovery machine 12c (for example, a vane motor) that rotates integrally with the rotating body of the absorption liquid pump 12a.

  The absorption liquid pump 12 a is connected to the concentrated absorption liquid pipe 31 and pumps the concentrated absorption liquid in the concentrated absorption liquid pipe 31 toward the regenerator 13.

  The power recovery machine 12c recovers the differential pressure between the absorber 11 and the regenerator 13, depressurizes the rare absorbent flowing from the regenerator 13 side, and supplies it to the absorber 11 side. The power recovery machine 12c is integrated with the shaft 12d of the absorption liquid pump 12a, recovers the differential pressure in the form of rotational energy of the shaft 12d, and rotates integrally with the absorption liquid pump 12a. That is, the power recovery machine 12c recovers power from the diluted absorbent flowing through the diluted absorbent pipe 32, and assists the drive of the absorbent pump 12a by the motor 12b with the recovered power.

  The absorber 11 causes the absorption liquid to absorb refrigerant gas supplied from the compression refrigeration circuit 20 described later. The absorber 11 is connected to a concentrated absorption liquid pipe 31 connected to the regenerator 13, and the absorber 11 sends the absorption liquid (concentrated absorption liquid) that has absorbed the refrigerant to the concentrated absorption liquid pipe 31.

  The regenerator 13 heats the concentrated absorbent supplied from the concentrated absorbent pipe 31 using, for example, various exhaust heats, and supplies it to the gas-liquid separation tank 14. The gas-liquid separation tank 14 separates the supplied concentrated absorbent into refrigerant gas and rare absorbent. The gas-liquid separation tank 14 includes a storage unit (not shown) that stores a rare absorbent. A refrigerant pipe 41 of the compression refrigeration circuit 20 indicated by a solid line is connected to the space above the storage part, a rare absorption liquid pipe 32 connected to the circulation pump 12 is connected to the lower part of the storage part, and an intermediate part of the storage part A rare absorbing liquid pipe 32 extending from the regenerator 13 is connected. The rare absorption liquid pipe 32 includes a bypass pipe 32 a through which the rare absorption liquid bypasses the circulation pump 12. The bypass pipe 32 a is provided so as to connect between the gas-liquid separation tank 14 and the circulation pump 12 and between the circulation pump 12 and the absorption liquid heat exchanger 17. The gas-liquid separation tank 14 separates the refrigerant gas from the concentrated absorption liquid, only the refrigerant gas is supplied to the compression refrigeration circuit 20, and the rare absorption liquid from which the refrigerant gas has been separated is the power recovery machine 12c or the flow rate of the circulation pump 12. It is supplied to the regulating valve 15.

  The absorber 11 operates at a saturation pressure determined by a saturation temperature in an evaporator 24 described later of the compression refrigeration circuit 20. On the other hand, the operating pressure of the regenerator 13 is made higher than the operating pressure of the absorber 11 in order to reduce the input of the compressor 21 by making the suction pressure of the compressor 21 higher than the pressure of the evaporator 24. Therefore, the absorption liquid pump 12 a of the circulation pump 12 boosts the concentrated absorption liquid supplied from the absorber 11 by the differential pressure and supplies the pressure to the regenerator 13.

  A concentrated absorption liquid pipe 31 is connected to the absorption liquid heat exchanger 17 between the circulation pump 12 and the regenerator 13, and a rare absorption liquid pipe 32 is connected between the circulation pump 12 and the absorber 11. In the absorption liquid heat exchanger 17, the concentrated absorption liquid is heated by the rare absorption liquid. As a result, the amount of heat given to the absorption liquid by heating in the regenerator 13 is recovered, and the efficiency of the absorption refrigeration circuit 10 is improved accordingly.

  Next, the compression refrigeration circuit 20 will be described. As shown in FIG. 1, the compression refrigeration circuit 20 includes a compressor 21, a condenser 22, an expansion valve 23, and an evaporator 24 in this order from the upstream side. These components of the compression refrigeration circuit 20 are connected to each other by a refrigerant pipe 41 indicated by a solid line extending from the gas-liquid separation tank 14 of the absorption refrigeration circuit 10 to the absorber 11. In the present embodiment, a radiator 25 is provided on the upstream side of the compressor 21 (that is, the gas-liquid separation tank 14 side).

  The compressor 21 is connected to the gas-liquid separation tank 14 via a radiator 25. The compressor 21 conveys the refrigerant gas separated in the gas-liquid separation tank 14 to the condenser 22 while increasing the pressure to an appropriate pressure level, for example, an arbitrary pressure value equal to or higher than the critical pressure. Further, the heat of the compressor 21 can be reduced by dissipating the refrigerant gas and lowering the temperature by the radiator 25 before flowing into the compressor 21.

  The condenser 22 is a so-called gas cooler, for example, performs heat exchange between the outside air and the refrigerant, cools the refrigerant, lowers the enthalpy, and condenses it.

  The expansion valve 23 functions as a flow rate adjustment valve, adjusts the flow rate of the refrigerant, and expands it by reducing the pressure. As a result, the refrigerant undergoes isoenthalpy expansion and becomes a refrigerant in a low-temperature and low-pressure and gas-liquid mixed state.

  The evaporator 24 evaporates the refrigerant having the latent heat to produce a cooling effect. The refrigerant that has evaporated in the evaporator 24 and has lost its cooling effect is supplied to the absorber 11 via the refrigerant pipe 41.

  Here, the absorption refrigeration apparatus 1 includes a space between the compressor 21 and the gas-liquid separation tank 14 in the refrigerant pipe 41 and a space between the gas-liquid separation tank 14 and the circulation pump 12 in the rare absorption liquid pipe 32 (this embodiment). In the embodiment, there is provided a refrigerant gas supply pipe (supply path) 42 connecting the upstream side of the bypass pipe 32a. A part of the refrigerant gas flowing toward the condenser 22 is taken out from the refrigerant pipe 41 on the upstream side of the compressor 21 by the refrigerant gas supply pipe 42 and is diluted on the upstream side of the circulation pump 12 and the bypass pipe 32a. Supplied into the tube 32.

  As described above, the rare absorption liquid pipe 32 is provided with the bypass pipe 32a that bypasses the circulation pump 12, and the flow rate adjusting valve 15 is disposed in the middle of the bypass pipe 32a. By adjusting the opening degree of the flow rate adjusting valve 15, the distribution of the mixture of the rare absorbent and the refrigerant gas flowing in the power recovery machine 12c and the bypass pipe 32a of the circulation pump 12 is adjusted, and the power recovery machine 12c is adjusted. The flow rate of the mixture is adjusted.

[2. Effect]
Hereinafter, with reference to FIG. 1, the effect of the absorption refrigeration apparatus 1 of embodiment of this invention is demonstrated.
(1) In the absorption refrigeration apparatus 1, a part of the refrigerant gas that is separated from the absorbing liquid and flows to the condenser 22 is supplied to the power recovery machine 12c. Here, since the power recovery machine 12c is a positive displacement type, supplying a part of the refrigerant gas to the power recovery machine 12c increases the volume of the fluid supplied to the power recovery machine 12c, thereby improving the power recovery efficiency. Can do.

  Further, the refrigerant gas is more easily dissolved in the rare absorbent as the temperature of the rare absorbent is lower. In the absorption refrigeration apparatus 1, the refrigerant gas is supplied to the rare absorbent before the temperature of the rare absorbent decreases as a result of the heat exchange of the rare absorbent with the concentrated absorbent in the absorbent heat exchanger 17. This prevents the refrigerant gas from dissolving into the rare absorbent. Therefore, according to the absorption refrigeration apparatus 1 of the present invention, the volume of the fluid supplied to the power recovery machine 12c can be effectively increased, and the power of the circulation pump 12 can be reduced by recovering the power by the power recovery machine 12c. The COP of the absorption refrigeration apparatus 1 can be improved.

  (2) In the present embodiment, the absorption liquid pump 12a and the power recovery machine 12c are both of the positive displacement type and directly connected by the rotating shaft 12d, and the volume of the absorption liquid pump 12a and the power recovery machine 12c is set to be the same. Has been. For this reason, the concentrated absorption liquid flowing through the absorption liquid pump 12a and the rare absorption liquid flowing through the power recovery machine 12c have the same volume flow rate. Since the density of the absorbing liquid changes depending on the refrigerant content and temperature, if the density of the concentrated absorbing liquid and that of the rare absorbing liquid differ, the concentrated absorbing liquid flowing from the absorber 11 to the regenerator 13 and the regenerator 13 from the absorber are absorbed. The mass flow rate balance with the rare absorbent flowing to 11 is lost, and the differential pressure between the absorber 11 and the regenerator 13 cannot be stably controlled to an appropriate target. In particular, when the refrigerant gas is allowed to flow through the power recovery machine 12c in addition to the rare absorbent, the mass flow rate balance is likely to be greatly lost. According to the absorption refrigeration apparatus 1 of the present invention, the flow rate of the rare absorbent between the power recovery machine 12c and the bypass pipe 32a is adjusted by adjusting the opening of the flow rate adjustment valve 15 provided in the middle of the bypass pipe 32a. It is possible to control the mass so that the balance of the mass is appropriate. Therefore, the differential pressure between the absorber 11 and the regenerator 13 can be stably maintained at an appropriate target value.

[3. Others]
(1) In the present invention, since the refrigerant gas originally used in the compression refrigeration circuit 20 is supplied to the power recovery machine 12c and used to drive the circulation pump 12, the output of the compression refrigeration circuit 20 is slightly reduced. To do. For this reason, whether the COP of the absorption refrigeration apparatus 1 as a whole is improved depends on the work amount obtained by supplying the refrigerant gas to the power recovery machine 12c. This work amount depends on the refrigerant transport capacity of the absorbing liquid (the amount of refrigerant that can be absorbed and transported by the absorbing liquid per unit amount), the recovery efficiency of the power recovery machine 12c, and the amount of exhaust heat that can be used in the regenerator 13. Become. Therefore, a valve is provided in the middle of the refrigerant gas supply pipe 42, and the work amount obtained by the power recovery machine 12c by supplying the refrigerant gas in consideration of the refrigerant transport capability, the recovery efficiency, and the amount of exhaust heat, the COP of the absorption refrigeration apparatus 1 is used. This valve may be closed when improvement of the above cannot be expected.

  (2) In the above embodiment, the example in which the absorption refrigeration apparatus of the present invention is applied to the compression absorption hybrid cycle using the compressor 21 for refrigerant compression has been described, but the present invention is not limited to this. For example, the compressor 21 is omitted from the configuration shown in FIG. 1, the refrigerant is pumped by the circulation pump 12 alone, and the refrigerant pump 12 is obtained so that the refrigerant pressure is the same as that when the compressor 21 is used. The output may be increased.

  (3) The present invention is not limited to the above-described object, and other functions and effects of the present invention may be achieved by the respective functions shown in the embodiments for carrying out the invention, which cannot be obtained by the conventional technology. It is.

  The present invention can be used for an absorption refrigeration apparatus that utilizes absorption of a refrigerant into an absorption liquid and release of the refrigerant from the absorption liquid.

DESCRIPTION OF SYMBOLS 1 Absorption-type refrigeration apparatus 10 Absorption-type refrigeration circuit 11 Absorber 12 Circulation pump 12a Absorption liquid pump (pressure | voltage riser)
12b Motor 12c Power recovery machine 13 Regenerator 14 Gas-liquid separation tank 15 Flow rate adjustment valve 17 Absorption liquid heat exchanger 20 Compression type refrigeration circuit 21 Compressor 22 Condenser 23 Expansion valve 24 Evaporator 25 Radiator 31 Concentrated absorption liquid pipe 32 Rare absorption liquid pipe 41 Refrigerant pipe 42 Refrigerant gas supply pipe (supply path)

Claims (2)

A pressure increasing device that pressurizes the absorbing liquid that has absorbed the refrigerant in the absorber toward the regenerator;
A positive displacement power recovery machine that recovers power from the absorbing liquid that travels from the regenerator to the absorber, and that drives the booster using the recovered power;
A supply path for supplying a part of the gaseous refrigerant separated from the absorbing liquid and directed to the condenser to the power recovery machine;
A heat exchanger for exchanging heat between the absorption liquid from the booster to the regenerator and the absorption liquid from the power recovery machine to the absorber;
An absorption refrigeration apparatus comprising: A bypass path for bypassing the power recovery machine to the mixture of the absorbing liquid and the gaseous refrigerant;
A flow regulator for adjusting the flow rate of the mixture in the bypass path;
The absorption refrigeration apparatus according to claim 1, further comprising:

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