JPH04125165U - Cooling system - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a cooling device that can cope with a sudden decrease in heat load and avoid liquid compression, even though it is not a large device. [Structure] This cooling device is equipped with a heat exchanger 4, a compressor 1, a condenser 2, an expansion valve 3, and a capacity adjustment valve 5. A separate heat exchanger 6 is incorporated. When the heat load suddenly decreases, the refrigerant pressure within the heat exchanger 4 also decreases rapidly, and the capacity adjustment valve 5, which is a pressure reducing valve, immediately opens wide. Therefore, a large amount of compressed refrigerant gas sent out from the compressor 1 is sent to another heat exchanger 6 side. The liquid refrigerant flowing out from the heat exchanger 4 is gasified by heat exchange with the high temperature compressed refrigerant gas flowing out from the capacity adjustment valve 5 via the heat exchanger 6.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This invention consists of a heat exchanger and a compressor for exchanging heat between a heat load and a refrigerant. A condenser that condenses the compressed refrigerant gas sent out into liquid refrigerant. The liquid refrigerant flow regulator diverts the compressed refrigerant gas sent from the compressor to the heat exchanger side. This relates to a cooling device consisting of a capacity adjustment valve that is rotated.

0002

[Conventional technology]

This type of cooling device is used for cooling, but the heat load of water, air, etc. is 0 to 100%. It fluctuates up to. When the heat load is 0%, the liquid refrigerant sent to the heat exchanger Liquid compression, which flows into the compressor without being evaporated, causes malfunctions in the compressor. There is always a possibility that it may occur. In conventional cooling systems, the expansion valve tends to close when the heat load decreases. This control in the closing direction reduces the refrigerant pressure within the heat exchanger. When the refrigerant pressure in the heat exchanger falls below the specified level, the capacity adjustment valve, which is a pressure reducing valve, opens wide. A large amount of the compressed refrigerant gas sent out from the compressor is detoured and supplied to the heat exchanger side. Opening/closing control of the expansion valve is performed based on temperature information on the refrigerant outlet side of the heat exchanger. heat exchange The temperature on the refrigerant outlet side of the converter reflects the heat load, and as the heat load increases, the outlet temperature will decrease. If the heat load increases and the heat load becomes smaller, the outlet side temperature will decrease. Typically this temperature is the gas pressure This gas pressure controls the opening and closing of the expansion valve. sudden heat load When it drops or disappears, the expansion valve closes. Such a flow rate The control adjusts the amount of liquid refrigerant introduced into the heat exchanger.

0003

[Problem that the idea aims to solve]

However, it takes some time for the thermal load fluctuation to affect the opening/closing control of the expansion valve. Therefore, if the heat load decreases rapidly, the liquid will drain before the expansion valve is controlled to open and close. Refrigerant flows into the heat exchanger. Using a capillary tube instead of an expansion valve In this case, the amount of liquid refrigerant flowing in will further increase. Liquid refrigerant is sent to the heat exchanger However, since there is no heat load, the liquid refrigerant does not evaporate, and the liquid refrigerant is sent to the compressor. It will be served.

0004 To prevent liquid refrigerant from entering the compressor, the liquid refrigerant is discharged from the heat exchanger. Installing an accumulator upstream of the compressor to temporarily hold the refrigerant, or even A measure has also been proposed in which the liquid refrigerant in the accumulator is gasified using a heater. Ru. However, even if you try to hold liquid refrigerant in an accumulator, the cooling performance will be limited. , from the perspective of cooling capacity design, there are restrictions on the amount of liquid refrigerant that can be held, and liquid cooling to the compressor is limited. It is not possible to avoid medium inflow. Necessary for gasifying liquid refrigerant using a heater In order to ensure a sufficient amount of heat, it is necessary to provide a separate power supply for the heater, which increases costs. There is a problem that

[0005] Another way to prevent liquid refrigerant from entering the compressor is to The extracted refrigerant is separated into liquid refrigerant and refrigerant gas by a gas-liquid separator, and the refrigerant gas is separated into liquid refrigerant and refrigerant gas. There is also a method in which the refrigerant is introduced into the compressor and the liquid refrigerant is returned to the heat exchanger again. With this method, the structure of piping etc. becomes complicated and the overall size becomes unavoidable. There is a problem.

[0006] This invention was created in view of the above problems, and its purpose is to However, it is possible to cope with a sudden decrease in heat load and avoid liquid compression. The objective is to provide a cooling device that can

[0007]

[Means to solve the problem]

In order to achieve the above objective, the present invention has developed A heat exchanger for heat exchange, a compressor for compressing refrigerant gas, and a A condenser that condenses the compressed refrigerant gas discharged into liquid refrigerant, which is located downstream of the condenser. Liquid refrigerant flow regulator, bypasses compressed refrigerant gas sent from the compressor to the heat exchanger side In a cooling device equipped with a capacity adjustment valve, the refrigerant flowing out from the heat exchanger and It incorporates another heat exchanger that exchanges heat with the refrigerant flowing out from the capacity regulating valve. Ru.

[0008]

[Effect]

When the heat load suddenly decreases, the refrigerant pressure inside the heat exchanger also decreases rapidly, reducing the capacity. The regulating valve immediately opens wide. Therefore, the compressed refrigerant gas sent out from the compressor is A large amount is sent to another heat exchanger side. The liquid refrigerant flowing out of the heat exchanger is another heat exchanger. This is achieved by heat exchange with the high temperature compressed refrigerant gas flowing out from the capacity adjustment valve via the converter. It is then gasified.

[0009]

【Example】

Examples embodying the present invention will be explained below with reference to FIGS. 1 and 2. do. As shown in Fig. 1, 1 is a compressor for compressing refrigerant gas. An accumulator 1a is installed on the upstream side to temporarily hold liquid refrigerant. . A condenser 2 is connected to the downstream side of the compressor 1. The compressed refrigerant gas that has been introduced is cooled by the blowing action of the fan 2a and becomes liquid refrigerant. An expansion valve 3 serving as a liquid refrigerant flow rate regulator is connected to the downstream side of the condenser 2. swelling The expansion valve 3 restricts the flow rate of liquid refrigerant sent out from the condenser 2. Downstream side of expansion valve 3 A heat exchanger 4 is connected to the heat exchanger 4, which exchanges the liquid refrigerant sent out from the expansion valve 3 with the heat load cycle. Heat exchange with a heat load such as air or water on the road R0 side is performed via a heat exchanger 4. These compressor 1, accumulator 1a, condenser 2, expansion valve 3 and heat exchanger 4 Therefore, a main flow path R1 of the refrigerant circuit is formed.

0010 A bypass path R is arranged in parallel to the condenser 2 and expansion valve 3 on the main flow path R1. 2 is connected to the main flow path R1. A pressure reducing valve type capacity adjustment valve 5 is provided, On the detour R2, communication of the detour R2 is cut off by a capacity regulating valve 5. capacity A heat exchanger 6 is connected downstream of the regulating valve 5 . The heat exchanger 6 is a capacity adjustment valve 5 Heat exchange is performed between the detour R2 on the downstream side of the heat exchanger 4 and the main flow path R1 on the downstream side of the heat exchanger 4. .

[0011] A temperature detector 7 is installed on the refrigerant outlet side of the heat exchanger 4. The temperature sensor 7 is The refrigerant outlet temperature in the heat exchanger 4 is converted and detected as gas pressure, and the detected gas pressure is expanded. The pressure is introduced into the expansion valve 3 as control pressure for controlling the opening and closing of the valve 3. expansion valve 3 is always slightly open. When the heat load decreases, the amount of heat given to the liquid refrigerant by the heat load body decreases, and the heat exchange The temperature on the refrigerant outlet side of the converter 4 decreases. Information on this temperature drop is obtained by the temperature sensor 7. This spreads to the expansion valve 3 as a decrease in the detected gas pressure, and the expansion valve 3 is controlled to tend to close. . The compressor 1 operates continuously, and the refrigerant in the heat exchanger 4 is constantly drawn into the compressor 1 side. It is. Therefore, by controlling the expansion valve 3 in the closing direction, the refrigerant pressure in the heat exchanger 4 is increased. Power decreases. When the refrigerant pressure in the heat exchanger 4 falls below a specified value, the capacity adjustment valve 5 opens. Since the detour R2 is communicated with the compressor 1, the compressed refrigerant gas sent out from the compressor A large amount of the heat exchanger 6 is detoured and supplied via the regulating valve 5 to the heat exchanger 6 side. Outflow from heat exchanger 4 The liquid refrigerant is mixed with the high temperature compressed refrigerant gas flowing out from the capacity adjustment valve 5 via the heat exchanger 6. It is gasified by heat exchange during the process.

0012 This heat exchange effect is explained based on the absolute pressure (p)-enthalpy (h) diagram in Figure 2. do. The curve SC 1 is the saturated liquid line, SC 2 is the saturated vapor line, and SC 0 is the absolute pressure P. This is the critical point for Closed curves A-B-C-D, A0 -B0 -C-D and A' -B'-C-D indicate different refrigeration cycles. The closed curve A0 -B0 -C-D indicates that the liquid refrigerant is just at the outlet of the heat exchanger 4. Dry saturated compression steam that has completed evaporation and is sent to the compressor 1 in the form of dry saturated vapor Shows the kuru. Dry saturated steam under the same pressure under normal conditions with no variation in heat load In order to maintain a constant degree of superheating, which is the temperature difference between The superheat compression cycle is set as A-B-C-D.

[0013] In the compression process between A and B, the absolute pressure increases from P0 to Pk, and the enthalpy becomes ha increases from hb to hb. In the condensation process between B and C, the absolute pressure is maintained at Pk, and the enter Rupee decreases from hb to hc. In the expansion process between C and D, the absolute pressure is from Pk to P The enthalpy is kept at hc. In the evaporation process between D and A, the absolute pressure is P0 is maintained, and enthalpy increases from hc to ha.

[0014] The liquid refrigerant sent to the heat exchanger 4 is gasified by the evaporation process, and at this time The amount of heat q1 absorbed from the heat load is expressed by the enthalpy difference ha - hc between D and A. . Also, the heat equivalent required for the compression work of the refrigerant gas by the compressor 1, that is, the heat equivalent due to the compression process. The amount of heat q2 obtained by the compressed refrigerant gas is expressed by the difference in enthalpy between A and B, hb −ha. Ru.

[0015] When the heat load decreases, the amount of heat q1 absorbed by the liquid refrigerant from the heat load decreases. Therefore, the evaporation process would normally take place between D and A', and the cooling cycle would follow the closed curve A'- Moving on to the wet compaction cycle shown as B'-C-D. However, compressed refrigerant gas A part of the obtained heat quantity q2 is transferred to the liquid refrigerant via another heat exchanger 6, so it is transferred to A'. The enthalpy value ha' of the liquid refrigerant approaches ha. This closes the refrigeration cycle. Returning to the superheated compression cycle of the chain curve A-B-C-D, only refrigerant gas is used as usual. is introduced into the compressor 1.

[0016] Generally, in such a cooling cycle, the amount of heat q1 absorbed by the liquid refrigerant from the heat load is The ratio to the amount of heat q2 obtained by the compressed refrigerant gas in the compression process is approximately 3:1. subordinate Therefore, even if the liquid refrigerant is sent out from the heat exchanger 4 due to the heat load becoming 0%, , a relatively large amount of liquid refrigerant, about 1/3 of which, is used for heat exchange through the heat exchanger 6. It evaporates more.

[0017] It takes some time for the expansion valve 3 to close after the heat load suddenly decreases, and this Meanwhile, the liquid refrigerant flowing into the heat exchanger 4 flows out into the compressor 1 as it is. this The amount of outflow exceeds the capacity of the accumulator 1a, and the liquid remains in the accumulator 1a. If the liquid refrigerant flows into the compressor 1, the liquid refrigerant will also enter the compressor 1. However, the compression process By using the heat obtained by the compressed refrigerant gas as the heat of evaporation of the liquid refrigerant, Even if the accumulator 1a is of normal size, it can sufficiently cope with the sudden decrease in heat load. , it is possible to reliably prevent liquid refrigerant from flowing into the compressor 1. Also, the liquid refrigerant is It is no longer necessary to provide a heater to the accumulator 1a for the purpose of This eliminates problems such as high costs associated with installing a separate power supply for the heater. stomach.

[0018] Of course, the present invention is not limited to the above-mentioned embodiment, and for example, the expansion valve 3 can be replaced with Even if a capillary tube is used in addition, a sufficient effect of preventing liquid compression can be obtained. Further, as in another embodiment shown in FIG. 3, between the main flow path R1 and the thermal load circuit R0, It is also possible to use a heat exchanger 8 that exchanges heat between the main flow path R1 and the bypass path R2. Wear. According to this method, a heat exchanger 6 separate from the heat exchanger 4 as in the above embodiment is assembled. The advantage is that the entire cooling system can be made more compact because there is no need to attach has.

[0019]

[Effect of the idea]

According to the cooling device of the present invention, even though it is not a large device, it is possible to rapidly increase the heat load. This has an excellent effect of being able to cope with the decrease and avoid liquid compression.

[Brief explanation of drawings]

FIG. 1 is a simplified diagram showing an embodiment of the cooling device of the present invention.

FIG. 2 is an absolute pressure-enthalpy diagram showing a refrigeration cycle.

FIG. 3 is a simplified diagram showing another embodiment of the invention.

[Explanation of symbols]

1 compressor, 2 condenser, 3 expansion valve as liquid refrigerant flow regulator, 4 heat exchanger, 5 capacity regulating valve, 6 (another) heat exchanger.

Claims (1)

[Scope of utility model registration request] Claim 1: A heat exchanger (4) for exchanging heat between a heat load such as water or air and a refrigerant, a compressor (1) for compressing refrigerant gas, and a refrigerant sent from the compressor (1). a condenser (2) for condensing compressed refrigerant gas into liquid refrigerant; a liquid refrigerant flow rate regulator (3) interposed on the downstream side of the condenser (2);
and a cooling device equipped with a capacity adjustment valve (5) that detours the compressed refrigerant gas sent out from the compressor (1) to the heat exchanger (4) side, the refrigerant flowing out from the heat exchanger (4) and the capacity adjustment. A cooling device characterized in that it incorporates another heat exchanger (6) that exchanges heat with the refrigerant flowing out from the valve (5).