CN205079493U - Two -stage overlapping formula cryogenic refrigeration system - Google Patents

Abstract

The utility model relates to a two-stage cascading low-temperature refrigeration system, comprising: a low-temperature refrigeration circulation circuit and a high-temperature refrigeration circulation circuit; the low-temperature refrigeration circulation circuit and the high-temperature refrigeration circulation circuit share a double-stage condenser and an intermediate exchanger Heater; the two-stage condenser includes a high-temperature stage and a low-temperature stage, the high-temperature stage of the two-stage condenser is connected to the high-temperature stage refrigeration cycle, and the low-temperature stage of the two-stage condenser is connected to the low-temperature stage refrigeration cycle; The high-temperature stage of the intermediate heat exchanger is connected to the high-temperature refrigeration cycle, and the low-temperature stage of the intermediate heat exchanger is connected to the low-temperature refrigeration cycle. The utility model has the advantages of easy control of the refrigerant charging amount, convenient maintenance, easy realization of a low temperature of -86°C under two refrigerants of R404A/R23, and good system operation stability, and belongs to the technical field of refrigeration systems.

Description

A Two-Stage Cascade Low-Temperature Refrigeration System

technical field

The utility model relates to a refrigeration system, in particular to a two-stage cascade low-temperature refrigeration system.

Background technique

In recent years, in the fields of low-temperature biological preservation, low-temperature medicine, freeze-drying and gas liquefaction, low temperatures below -60°C are often required. In order to solve the refrigeration problem below -60°C, a multi-element mixed working medium refrigeration cycle system is often used, including the classic cascade system and the natural cascade system. In the natural cascade refrigeration system cycle, various refrigerants are separated by themselves through the gas-liquid separator to realize cascade between high-boiling point refrigerants and low-boiling point refrigerants to obtain lower evaporation temperatures. However, there is a serious problem in this system, that is, the system stability is poor. Once some pipelines in the system leak, it is difficult to judge the quality of the leakage in the system. It is very difficult; at the same time, in a natural cascade system, it is difficult to use R404A/R23 refrigerants to achieve a low temperature of -86°C. Due to the preciousness of medical specimens, no problems are allowed during the preservation process, which puts stricter requirements on the stability of the cryogenic system.

Utility model content

Aiming at the technical problems existing in the prior art, the purpose of this utility model is to provide a two-stage cascade low-temperature refrigeration system that can easily achieve a low temperature of -86°C, is easy to maintain, and has good stability.

In order to achieve the above object, the utility model adopts the following technical solutions:

A two-stage cascaded low-temperature refrigeration system, including: a low-temperature stage refrigeration cycle loop and a high-temperature stage refrigeration cycle loop; the low-temperature stage refrigeration cycle loop and the high-temperature stage refrigeration cycle loop share a double-stage condenser and an intermediate heat exchanger; The two-stage condenser includes a high-temperature stage and a low-temperature stage. The high-temperature stage of the two-stage condenser is connected to the high-temperature stage refrigeration cycle, and the low-temperature stage of the two-stage condenser is connected to the low-temperature stage refrigeration cycle; the intermediate heat exchanger includes a high-temperature stage and a low-temperature stage. , the high-temperature stage of the intermediate heat exchanger is connected to the high-temperature refrigeration circulation circuit, and the low-temperature stage of the intermediate heat exchanger is connected to the low-temperature refrigeration circulation circuit. The refrigerating temperature of the high-temperature refrigeration cycle loop in the utility model is higher than that of the low-temperature refrigeration circulation loop, and the two are named because of the relative temperature, rather than absolute high temperature or absolute low temperature.

As a preference, the high-temperature stage refrigeration cycle circuit includes: a first compressor, a first oil separator, a first dry filter, a first regenerator, and a first throttling device; wherein there are four first regenerators The interfaces are the inlet of the high-pressure end, the outlet of the high-pressure end, the inlet of the low-pressure end, and the outlet of the low-pressure end; along the flow direction of the refrigerant, the first compressor, the first oil separator, the high-temperature stage of the two-stage condenser, and the first dry filter The inlet of the high-pressure end of the first regenerator, the outlet of the high-pressure end of the first regenerator, the first throttling device, the high-temperature stage of the intermediate heat exchanger, and the inlet of the low-pressure end of the first regenerator are connected in sequence. The outlet of the low-pressure end of a regenerator is connected to the first compressor; the low-temperature stage refrigeration cycle includes: the second compressor, the second oil separator, the second dry filter, the second regenerator, and the second section flow device, evaporator; the second regenerator has four ports, which are high-pressure end inlet, high-pressure end outlet, low-pressure end inlet, and low-pressure end outlet; along the flow direction of the refrigerant, the second compressor, two-stage condensing The low temperature stage of the device, the second oil separator, the low temperature stage of the intermediate heat exchanger, the second dry filter, the inlet of the high pressure end of the second regenerator, the outlet of the high pressure end of the second regenerator, and the second throttling device , the evaporator, and the inlet of the low-pressure end of the second regenerator are connected in sequence, and the outlet of the low-pressure end of the second regenerator is connected with the second compressor.

As a preference, the high-temperature refrigeration cycle is an R404A refrigeration cycle; the low-temperature refrigeration cycle is an R23 refrigeration cycle.

As a preference, the two-stage condenser is a copper tube-fin two-stage condenser, and the high-temperature stage and the low-temperature stage realize independent operation through independent outlets and inlets.

As a preference, a two-stage cascaded low-temperature refrigeration system is installed in a refrigerator.

As a preference, the freezer is a freezer with an effective volume of 500 to 600 liters; the evaporator is a wire tube evaporator with an inner diameter of 5 to 8 mm and a heat exchange area of 0.8 to 1.2 square meters; the intermediate heat exchanger is 2 to 5 A sleeve-and-tube heat exchanger with a capacity of 2 to 5 kilowatts, or a plate heat exchanger with a capacity of 2 to 5 kilowatts; the first compressor is a compressor with a displacement of 28 to 36 milliliters; the second compressor is a compressor with a displacement of 25 to 36 milliliters Compressor with a displacement of 33 ml; the first throttling device is a thermal expansion valve with a cooling capacity of 1.5 to 2.5 kW, or a capillary tube with an inner diameter of 1.5 mm and a length of 1000 to 2000 mm; the second throttling device is 0.7 to 1.5 kW A thermostatic expansion valve for cooling capacity, or a capillary tube with an inner diameter of 1.5 mm and a length of 4000 to 5000 mm.

As a preference, the first throttling device is a thermal expansion valve or a capillary tube. The second throttling device is a thermal expansion valve or a capillary tube.

In general, the utility model has the following advantages:

1. The high-temperature and low-temperature stages of the two-stage condenser simultaneously dissipate heat from the refrigerant in the high- and low-temperature refrigeration cycle, and the low-temperature stage pre-cools the high-temperature and high-pressure refrigerant at the exhaust port of the second compressor, reducing the intermediate thermal load on the heat exchanger while increasing the efficiency of the second oil separator.

2. Realize the subcooling of the refrigerant through the first regenerator and the second regenerator, so that the 500 to 600 liter freezer can achieve a low temperature of -86°C under the two refrigerants of R404A/R23.

3. The low-temperature refrigeration cycle and the high-temperature refrigeration cycle operate independently without a gas-liquid separator, and the refrigerant charge is easy to control, which significantly improves the stability of the system.

4. The parameter configuration of the entire system and the combination of two refrigerants enable the system to achieve a low temperature of -86°C under the two refrigerants of R404A/R23. Good stability.

5. During system maintenance, the refrigerant charging amount can be increased or decreased according to the normal operating pressure of high and low temperature levels, which is convenient for maintenance.

Description of drawings

Fig. 1 is a structural schematic diagram of a two-stage cascade low-temperature refrigeration system.

Fig. 2 is a schematic diagram of the structure of the evaporator in the refrigerator.

Fig. 3 is a three-dimensional solid diagram of the evaporator.

Among them, 1 is the first compressor, 2 is the first oil separator, 3 is the two-stage condenser, 4 is the first dry filter, 5 is the first regenerator, 6 is the first throttling device, 7 is Intermediate heat exchanger, 8 is the second dry filter, 9 is the second regenerator, 10 is the second throttling device, 11 is the evaporator, 12 is the second oil separator, 13 is the second compressor.

detailed description

The utility model will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

Embodiment one

A two-stage cascaded low-temperature refrigeration system includes: a low-temperature stage refrigeration cycle circuit and a high-temperature stage refrigeration cycle circuit, and the two-stage refrigeration cycle circuits share a double-stage condenser and an intermediate heat exchanger. The R404A and R23 high-temperature and high-pressure gases injected into it are initially cooled by a two-stage condenser to reduce the load of the intermediate heat exchanger; the return pipe of the high and low temperature refrigeration system can be wound by the high and low temperature system capillary to realize the cooling of the refrigerant R404A and the refrigerant The supercooling of R23 reduces the load of the high-temperature compressor and R23 achieves a negative evaporation pressure after throttling in the capillary tube, and it is easy to achieve a low temperature of -86°C in the box. The high and low temperature refrigeration cycle systems operate independently, and the refrigerant is added according to the normal operating pressure of the unit during maintenance, so that the stable operation of the unit can be easily realized. Both the two-stage condenser and the intermediate heat exchanger include a high-temperature stage and a low-temperature stage. Both the first regenerator and the second regenerator include a high-pressure end inlet, a high-pressure end outlet, a low-pressure end inlet and a low-pressure end outlet.

The high-temperature stage refrigeration cycle is as follows: the exhaust pipe of the first compressor is connected to the inlet of the first oil separator, the outlet of the first oil separator is connected to the high-temperature stage inlet of the two-stage condenser, and the high-temperature stage outlet of the two-stage condenser is connected to the first oil separator. The inlet of a dry filter is connected, the outlet of the first dry filter is connected with the inlet of the high-pressure end of the first regenerator, the outlet of the high-pressure end of the first regenerator is connected with the inlet of the first throttling device, and the outlet of the first throttling device It is connected with the inlet of the high temperature stage of the intermediate heat exchanger, the outlet of the high temperature stage of the intermediate heat exchanger is connected with the inlet of the low pressure end of the first regenerator, and the outlet of the low pressure end of the first regenerator is connected with the gas return pipe of the first compressor. R404A refrigerant is injected into the high-temperature stage refrigeration cycle, the refrigerant enters the first oil separator after passing through the first compressor, condenses through the high-temperature stage of the double-stage condenser, enters the first dry filter, and then enters the high-pressure end of the first regenerator Supercooled, after throttling through the first throttling device, enter the high temperature stage of the intermediate heat exchanger for evaporative refrigeration, pass through the low pressure end of the first regenerator, and then return to the first compressor.

The low-temperature stage refrigeration cycle is as follows: the exhaust pipe of the second compressor is connected to the low-temperature stage inlet of the two-stage condenser, the low-temperature stage outlet of the two-stage condenser is connected to the inlet of the second oil separator, and the outlet of the second oil separator is connected to the middle The inlet of the low-temperature stage of the heat exchanger is connected, the outlet of the low-temperature stage of the intermediate heat exchanger is connected with the inlet of the second dry filter, the outlet of the second dry filter is connected with the inlet of the high-pressure end of the second regenerator, and the high-pressure end of the second regenerator The port outlet is connected to the inlet of the second throttling device, the outlet of the second throttling device is connected to the inlet of the evaporator, the outlet of the evaporator is connected to the inlet of the low pressure end of the second regenerator, and the outlet of the low pressure end of the second regenerator is connected to the compressor The machine returns to the trachea. The low-temperature refrigerant circulation circuit injects R23 refrigerant. After being compressed by the second compressor, the refrigerant enters the low-temperature stage of the two-stage condenser for pre-cooling, and then enters the intermediate heat exchanger through the second oil separator for condensation. The condensed low-temperature After being dried by the second drying filter, the refrigerant enters the high-pressure end of the second regenerator to be supercooled, enters the second throttling device to throttle, enters the evaporator to evaporate, passes through the low-pressure end of the second regenerator, and finally returns to the second regenerator. Two compressors.

A two-stage cascade cryogenic refrigeration system is installed in the freezer.

The component selection of a two-stage cascade low-temperature refrigeration system is as follows: the two-stage condenser is a copper tube fin condenser, the low-temperature stage pre-cools the R23 refrigerant, and the high-temperature stage condenses the R404A refrigerant, which can effectively Reduce the heat load of the intermediate heat exchanger and improve the thermal efficiency of the system.

The freezer is a 508L freezer, and the thickness of the foam layer is 12cm;

The evaporator is a five-layer Φ8 wire tube evaporator located in the refrigerator;

The intermediate heat exchanger is a 2P casing heat exchanger;

The displacement of the first compressor is 34.5 milliliters;

The displacement of the second compressor is 30.5 milliliters;

The first throttling device is a thermal expansion valve with a cooling capacity of 2.1 kW;

The second throttling device is a capillary with an inner diameter of 1.5 mm and a length of 4000 mm.

Embodiment two

In this embodiment, both the first throttling device and the second throttling device are capillary tubes.

Parts not mentioned in this embodiment are the same as in Embodiment 1.

The utility model uses two kinds of refrigerants to reach -86°C, the key lies in the optimal configuration of system parameters, at the same time, the volume of the compressor, the length of the capillary, the loading amount of high and low temperature refrigerants, and the supercooling mode of high and low temperature refrigerants. Avoiding the matching of the refrigerant charging amount during the maintenance of the natural cascade system and reducing the difficulty of regulating the stable operation of the system.

The above-mentioned embodiment is a preferred implementation mode of the utility model, but the implementation mode of the utility model is not limited by the above-mentioned example, and any other changes, modifications, substitutions, Combination and simplification should all be equivalent replacement methods, and are all included in the protection scope of the present utility model.

Claims (8)

1. A two-stage cascaded low-temperature refrigeration system, characterized in that: comprising: a low-temperature stage refrigeration cycle loop and a high-temperature stage refrigeration cycle loop; a low-temperature stage refrigeration cycle loop and a high-temperature stage refrigeration cycle loop share a double-stage condenser and a intermediate heat exchanger; The two-stage condenser includes a high-temperature stage and a low-temperature stage, the high-temperature stage of the two-stage condenser is connected to the high-temperature stage refrigeration cycle, and the low-temperature stage of the two-stage condenser is connected to the low-temperature stage refrigeration cycle; The intermediate heat exchanger includes a high-temperature stage and a low-temperature stage. The high-temperature stage of the intermediate heat exchanger is connected to the high-temperature refrigeration cycle circuit, and the low-temperature stage of the intermediate heat exchanger is connected to the low-temperature refrigeration cycle circuit. 2. A two-stage cascade low-temperature refrigeration system according to claim 1, wherein the high-temperature stage refrigeration cycle circuit comprises: a first compressor, a first oil separator, a first dry filter, The first regenerator and the first throttling device; the first regenerator has four ports, which are the inlet of the high-pressure end, the outlet of the high-pressure end, the inlet of the low-pressure end, and the outlet of the low-pressure end; along the flow direction of the refrigerant, the first Compressor, first oil separator, high temperature stage of two-stage condenser, first dry filter, inlet of high pressure end of first regenerator, outlet of high pressure end of first regenerator, first throttling device, intermediate The high-temperature stage of the heat exchanger and the inlet of the low-pressure end of the first regenerator are connected in sequence, and the outlet of the low-pressure end of the first regenerator is connected with the first compressor; the low-temperature stage refrigeration cycle includes: the second compressor, The second oil separator, the second dry filter, the second regenerator, the second throttling device, and the evaporator; the second regenerator has four ports, which are the inlet of the high pressure end, the outlet of the high pressure end, and the low pressure end Inlet, low-pressure end outlet; along the flow direction of refrigerant, the second compressor, the low-temperature stage of the two-stage condenser, the second oil separator, the low-temperature stage of the intermediate heat exchanger, the second dry filter, the second heat recovery The high-pressure end inlet of the second regenerator, the high-pressure end outlet of the second regenerator, the second throttling device, the evaporator, and the low-pressure end inlet of the second regenerator are connected in sequence, and the low-pressure end outlet of the second regenerator is connected with the first The two compressors are connected. 3. A two-stage cascade low-temperature refrigeration system according to claim 2, characterized in that: the high-temperature stage refrigeration cycle is an R404A refrigeration cycle; the low-temperature stage refrigeration cycle is an R23 refrigeration cycle. 4. A two-stage cascade low-temperature refrigeration system according to claim 2, wherein the two-stage condenser is a copper tube-fin two-stage condenser. 5. A two-stage cascade low-temperature refrigeration system according to claim 3, characterized in that it is installed in a refrigerator. 6. A two-stage cascade low-temperature refrigeration system according to claim 5, wherein the refrigerator is a refrigerator with an effective volume of 500 to 600 liters; The evaporator is a wire tube evaporator with an inner diameter of 5 to 8 mm and a heat exchange area of 0.8 to 1.2 square meters; The intermediate heat exchanger is a casing heat exchanger with a heat exchange capacity of 2 to 5 kW, or a plate heat exchanger with a heat exchange capacity of 2 to 5 kW; The first compressor is a compressor with a displacement of 28 to 36 milliliters; The second compressor is a compressor with a displacement of 25 to 33 milliliters; The first throttling device is a thermal expansion valve with a cooling capacity of 1.5 to 2.5 kilowatts, or a capillary tube with an inner diameter of 1.5 mm and a length of 1000 to 2000 mm; The second throttling device is a thermal expansion valve with a refrigeration capacity of 0.7 to 1.5 kilowatts, or a capillary tube with an inner diameter of 1.5 millimeters and a length of 4000 to 5000 millimeters. 7. The two-stage cascade low-temperature refrigeration system according to claim 2, wherein the first throttling device is a thermal expansion valve or a capillary tube. 8. The two-stage cascade low-temperature refrigeration system according to claim 2, wherein the second throttling device is a thermal expansion valve or a capillary tube.