CN101446455B - Method for preparing multi-temperature refrigerator with variable evaporation temperature - Google Patents

Abstract

The invention discloses an operation method of a multi-temperature refrigerator with variable evaporation temperature, which adopts a single compressor, a condenser, a gas-liquid separator, a condensation evaporator, a throttle valve, an evaporator and a three-way flow distribution valve As a component, the refrigerant used is a multi-component non-azeotropic mixed refrigerant; on the basis of the original self-cascading cycle, an evaporator for a high-temperature compartment or a variable-temperature compartment, and 1 or 2 three-way flow distribution valves are added to utilize The characteristics of multi-component non-azeotropic mixed refrigerants can adjust the composition of the mixed refrigerant entering the evaporator, and provide two or three different evaporation temperatures under the same evaporation pressure, and the evaporation temperature of the first stage can be customized according to user requirements to make adjustments. Applicable multi-component non-azeotropic mixed refrigerants are composed of low-boiling point refrigerants and high-boiling point refrigerants, and one or more components of the non-azeotropic mixed refrigerants are selected from each of the two groups of high-boiling point refrigerants and low-boiling point refrigerants. . It has the characteristics of convenient control and energy-saving operation.

Description

Method of operation of a multi-temperature refrigerator with variable evaporating temperature

technical field

The invention relates to a multi-temperature refrigerator which can provide a lower compartment temperature and has a variable evaporation temperature of one stage and the non-azeotropic mixed working medium used, especially relates to a kind of mixed refrigerant group which can be adjusted by entering into the evaporator The operation method of the multi-temperature refrigerator with multi-stage evaporation temperature and the non-azeotropic mixed working medium used to realize the adjustment of the evaporation temperature.

Background technique

The freezing and refrigeration of food or medical supplies is one of the most widely used areas of commercial refrigeration. At present, the main form of this type of device is the "one machine with multiple temperatures" refrigeration device. The "one machine with multiple temperatures" type refrigeration device is to adapt to the different storage temperatures of different storages. A refrigeration system that provides multiple compartment temperatures with one compressor is widely used because of its simple process. However, although these "one machine and multiple temperature" refrigeration devices can provide multiple compartment temperatures, due to the use of a single refrigerant, there is only one stage in the refrigerant cycle that corresponds to the evaporation temperature of the lowest compartment temperature, which makes the refrigerant There is a large heat transfer temperature difference when providing cooling capacity to other compartments, the energy cannot be fully utilized reasonably, and there are difficulties in controlling the temperature of each compartment. Taking the current typical dual-temperature refrigerator (refrigerated refrigerator) as an example, the temperatures of the refrigerator and freezer are maintained at 5°C and -24°C respectively, but the evaporation temperature of the refrigerant in the evaporator of the refrigerator and freezer is at Around -30°C, it will inevitably lead to a large heat transfer temperature difference in the refrigerator, resulting in the loss of effective energy, which will reduce the effective energy utilization coefficient of the entire system, and the too low evaporation temperature will increase the dry consumption of the storage in the refrigerator, and accelerate The aging process of fruits and vegetables. Therefore, only if the refrigeration system adopts two independent evaporators to provide two different evaporation temperatures and match the cooling temperatures of the two rooms respectively, can the above-mentioned problems be completely solved.

In addition, for the same compartment, when cooling different storage items, the compartment temperature also needs to be able to be changed and adjusted to match the optimum storage temperature of the storage items. High-quality, diversified fresh-keeping requirements are equipped with variable temperature compartments. The temperature of the variable temperature compartments can be changed between refrigerated compartments and frozen compartments to provide optimal storage temperatures for different foods. However, the evaporation temperature of the variable temperature compartment of the existing refrigerator is generally the evaporation temperature of the freezing compartment. Although the temperature of the variable temperature compartment changes, the evaporation temperature does not change, and the large heat transfer temperature difference will also bring effective energy. Increased loss, increased food dry consumption, etc. Only when the evaporation temperature of the variable temperature compartment can change with the temperature of the compartment, and provide a variable evaporation temperature for the multi-temperature refrigerator, can the high-quality fresh-keeping refrigeration of the variable temperature compartment be satisfied. .

When the existing refrigerator adopts the vapor compression cycle (single-stage compression) of a single refrigerant, it cannot meet the requirement that the room temperature drop to about -40°C. This is because when the difference between the evaporation temperature and the condensation temperature is large, the Less than one refrigerant is able to meet the lower condensing pressure and higher evaporating pressure. But some seafood needs to be stored in a room below -40°C, and when the multi-temperature refrigerator is used in the medical field to store medicines and medical supplies, it also needs to have a lower room temperature, so it can provide a temperature below -40°C Multi-temperature refrigerators at room temperature will have a wider range of applications.

Contents of the invention

Aiming at the problems of the above-mentioned multi-temperature refrigerating machine, such as the reduction of the effective energy utilization coefficient and the difficulty in controlling the temperature of each compartment due to only having one-stage evaporation temperature, the purpose of the present invention is to provide a multi-temperature refrigerator with variable evaporation temperature. The operation method of the refrigerator, which is based on the improved self-cascading refrigeration cycle, has two or three different evaporation temperatures, and the evaporation temperature of the first stage can be adjusted within a certain range according to the required compartment temperature, and provides It is applicable to the zeotropic mixed working medium of the multi-temperature refrigerator.

In order to achieve the above tasks, the present invention takes the following technical solutions:

A method for operating a multi-temperature refrigerator with variable evaporation temperature, characterized in that it includes a refrigeration compressor A, a condenser B, a gas-liquid separator C, a condensing evaporator D, a first throttle valve F1 and a second Throttle valve F2, high-temperature compartment evaporator E1, low-temperature compartment evaporator E2 and three-way flow distribution valve J1, the multi-temperature refrigerator can provide two different evaporation temperatures; when only the storage temperature of the low-temperature compartment needs to be changed , the change of the evaporation temperature of the low-compartment evaporator E2 can be realized by adjusting the components of the multi-component zeotropic mixture entering the low-compartment evaporator E2 through the three-way flow distribution valve J1;

The high-pressure exhaust port of the refrigeration compressor A is connected to the condenser B. In the condenser B, the mixed refrigerant vapor is partially condensed into a gas-liquid two-phase and enters the gas-liquid separator C. The gas-liquid separator C will contain relatively The gas-phase working medium containing many low-boiling point component refrigerants and the liquid-phase working medium containing more high-boiling point component refrigerants are separated, and the liquid-phase working medium is throttled by the first throttle valve F1 and then all enter the high-temperature evaporator E1; The gas-phase working medium is condensed into a saturated or subcooled liquid through the condensing evaporator D, and then all enter the low-temperature compartment evaporator E2 after being throttled by the second throttle valve F2;

When it is necessary to adjust the evaporation temperature of the low-temperature compartment evaporator E2, adjust it through the three-way flow distribution valve J1 at the outlet of the high-temperature compartment evaporator E1, so that the high-temperature compartment evaporator E1 contains more high-boiling point components to be refrigerated Part or all of the high-temperature mixed working fluid of the refrigerant enters the low-compartment evaporator E2, thereby changing the evaporation temperature of the low-compartment evaporator E2 by adjusting the composition and flow rate of the mixed refrigerant entering the low-compartment evaporator E2; all refrigerant Mix before the condensing evaporator D, and absorb heat in the condensing evaporator D to become saturated or superheated gas, and enter the suction port of compressor A.

The multi-component non-azeotropic mixed refrigerant is composed of low boiling point working fluid and high boiling point working medium, wherein the low boiling point working fluid includes: tetrafluoromethane, ethylene, ethane, monofluoroethylene, perfluoroethylene, trifluoromethane, Monofluoromethane, perfluoroethane, carbon dioxide, difluoromethane, pentafluoroethane, trifluoroethane, monofluoroethane, propylene, propane, difluorochloromethane, pentafluorochloroethane, perfluoropropane One of them or a mixture of several;

High boiling point working fluids include: propadiene, cyclopropane, 1,1,1,2-tetrafluoroethane, 1,1-difluoroethane, isobutane, n-butane, 1-butene, isobutene, 1,1,1,2,3,3,3-heptafluoropropane, 1,1,1,3,3,3-hexafluoropropane, 1,1,2,2,3-pentafluoropropane, tetrafluorochloro One of ethane or its mixture;

The total mass concentration of the low-boiling point working substance is 15%-45%; the total mass concentration of the high-boiling point working substance is 55%-85%, and the sum of the mass concentrations of the two groups of substances is 100%.

The method of the present invention only uses a single compressor, and on the basis of improving the self-cascade cycle, utilizes the characteristics of the non-azeotropic mixed refrigerant to adjust the composition of the mixed refrigerant entering the evaporator, and provide two refrigerants under the same evaporation pressure. There are two or three different evaporating temperatures, and the evaporating temperature of the first stage can be adjusted and changed according to the temperature requirements of the compartment, so that the temperature of the compartment and the evaporating temperature of the evaporator maintain a better heat transfer temperature difference, which not only improves the effective energy utilization coefficient but also Reduced storage consumption.

Description of drawings

Fig. 1 is a multi-temperature refrigerator cycle flow diagram with two-stage evaporating temperatures and the evaporating temperature of the high-temperature evaporator can be adjusted within a certain range in the present invention.

Fig. 2 is a flow chart of the cycle of a multi-temperature refrigerator with two-stage evaporating temperatures and the evaporating temperature of the low-temperature evaporator can be adjusted within a certain range in the present invention.

Fig. 3 is a multi-temperature refrigerator cycle flow diagram with three stages of evaporating temperature and one evaporator whose evaporating temperature can be adjusted within a certain range according to the present invention.

The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

Detailed ways

The method of the present invention adopts a single compressor and its condenser, gas-liquid separator, condensation evaporator, throttle valve, evaporator and three-way flow distribution valve as components to manufacture a multi-temperature refrigerator with variable evaporation temperature, The refrigerant adopts multiple non-azeotropic mixed refrigerants; on the basis of the self-cascading cycle, an evaporator for high-temperature compartments and variable-temperature compartments, 1 or 2 three-way flow distribution valves are added, and the non-azeotropic mixing process is used. Due to the different characteristics of the gas and liquid phase components in phase equilibrium, the high boiling point working medium and the low boiling point working medium are separated through the condenser and the gas-liquid separator and enter two refrigeration cycles for cascading to achieve a lower refrigeration temperature. The composition of the mixed refrigerant entering the evaporator is adjusted to provide two or three different evaporation temperatures under the same evaporation pressure, and the evaporation temperature of the first stage can be adjusted according to the temperature requirements of the compartment. Since a compressor is used to realize cascade refrigeration, the number of moving parts is reduced, and it is simple and reliable.

The non-azeotropic working fluid used in the multi-temperature refrigerator is composed of low boiling point working fluid and high boiling point working medium, among which the low boiling point working fluid includes: tetrafluoromethane, ethylene, ethane, monofluoroethylene, perfluoroethylene, three Fluoromethane, monofluoromethane, perfluoroethane, carbon dioxide, difluoromethane, pentafluoroethane, trifluoroethane, monofluoroethane, propylene, propane, difluorochloromethane, pentafluorochloroethane, Perfluoropropane or its mixture; high boiling point working fluids include: propadiene, cyclopropane, 1,1,1,2-tetrafluoroethane, 1,1-difluoroethane, isobutane, n-butane, 1-butene, isobutene, 1,1,1,2,3,3,3-heptafluoropropane, 1,1,1,3,3,3-hexafluoropropane, 1,1,2,2,3-pentafluoropropane Fluoropropane, tetrafluorochloroethane or their mixtures; the total mass concentration of the low boiling point working substance is: 15% to 45%; the total mass concentration of the high boiling point working substance is: 55% to 85%. The sum of the mass concentrations is 100%. Select one or several component refrigerants from these two groups of high and low boiling point refrigerants as non-azeotropic mixed refrigerants, and a compressor can be used in the above-mentioned improved self-cascading multi-temperature refrigerator device. The machine provides multi-stage evaporation temperature and the purpose of which the first-stage evaporation temperature is variable.

Embodiment 1: Referring to Figure 1, there is a multi-temperature refrigerator with two-stage evaporation temperature and the evaporation temperature of the high-temperature evaporator can be adjusted within a certain range, including a refrigeration compressor A, a condenser B, a gas-liquid separator C, and a condensation evaporator D. The first throttle valve F1 and the second throttle valve F2, the high temperature evaporator E1, the low temperature evaporator E2 and the three-way flow distribution valve J2. The device uses a two-element or multi-element non-azeotropic mixed working medium, and its cycle flow is: the high-pressure exhaust port of the refrigeration compressor A is connected to the condenser B, and the mixed refrigerant vapor is partially condensed in the condenser B to become a gas-liquid The two phases enter the gas-liquid separator C, and in the gas-liquid separator C, the gas-phase working medium containing more low-boiling point component refrigerants and the liquid-phase working medium containing more high-boiling point component refrigerants are separated, and the liquid phase After being throttled by the first throttle valve F1, the working fluid all enters the high-temperature evaporator E1; the gas-phase working fluid is condensed into a saturated or supercooled liquid by the condensing evaporator D, and then all enters the low-temperature evaporator E2 after being throttled by the second throttle valve F2 . When it is necessary to adjust the evaporation temperature of the high-temperature evaporator E1, it can be adjusted through the three-way flow distribution valve J2 at the outlet of the low-temperature evaporator E2, so that the low-temperature mixing process containing more low-boiling component refrigerants coming out of the low-temperature evaporator E2 Part or all of the refrigerant enters the high-temperature evaporator E1, so that the evaporation temperature of the high-temperature evaporator can be adjusted by adjusting the composition and flow rate of the mixed working fluid entering the high-temperature evaporator; all refrigerants are mixed before the condensing evaporator D, and evaporated after condensation The heat absorbed in the compressor becomes saturated or superheated gas, which enters the suction port of the compressor.

When the ambient temperature is 25°C, the non-azeotropic mixed working fluid used in the multi-temperature refrigerator is selected from the above-mentioned low boiling point working medium group and high boiling point working medium group. The function of the evaporation temperature of the high temperature evaporator is shown in Table 1 below:

Table 1:

project Mixture 1 mass concentration% Mixture 2 mass concentration% Mixture 3 mass concentration% Low boiling point working fluid 15 (difluoromethane) 30 (difluoromethane) 45 (difluoromethane) High boiling point working fluid 68 (isobutane) and 17 (1,1,1,2-tetrafluoroethane) 63 (isobutane) and 7 (1,1,1,2-tetrafluoroethane) 50 (isobutane) and 5 (1,1,1,2-tetrafluoroethane) Average evaporation temperature of low temperature evaporator (℃) -28 -32 -35 Variation range of average evaporation temperature of high temperature evaporator (℃) -15～0 -17～-3 -20～-5

Embodiment 2: Referring to Figure 2, there is a multi-temperature refrigerator with two-stage evaporating temperature and the evaporating temperature of the low-temperature evaporator can be adjusted within a certain range, including a refrigeration compressor A, a condenser B, a gas-liquid separator C, and a condensation evaporator D. The first throttle valve F1 and the second throttle valve F2, the high temperature evaporator E1, the low temperature evaporator E2 and the three-way flow distribution valve J1. The device uses a two-element or multi-element non-azeotropic mixed working medium, and its cycle flow is: the high-pressure exhaust port of the refrigeration compressor A is connected to the condenser B, and the mixed refrigerant vapor is partially condensed in the condenser B to become a gas-liquid The two phases enter the gas-liquid separator C, and in the gas-liquid separator C, the gas-phase working medium containing more low-boiling point component refrigerants and the liquid-phase working medium containing more high-boiling point component refrigerants are separated, and the liquid phase After being throttled by the first throttle valve F1, the working fluid all enters the high-temperature evaporator E1; the gas-phase working fluid is condensed into a saturated or supercooled liquid by the condensing evaporator D, and then all enters the low-temperature evaporator E2 after being throttled by the second throttle valve F2 . When it is necessary to adjust the evaporation temperature of the low-temperature compartment evaporator E2, it can be adjusted through the three-way flow distribution valve J1 at the outlet of the high-temperature evaporator E1, so that the high-temperature refrigerant containing more high-boiling point components coming out of the high-temperature evaporator E1 Part or all of the mixed refrigerant enters the low-temperature evaporator E2, thereby changing the evaporation temperature of the low-temperature compartment evaporator E2 by adjusting the composition and flow rate of the mixed refrigerant entering the low-temperature evaporator E2; all refrigerants are mixed before the condensing evaporator D , and absorb heat in the condensing evaporator D to become saturated or superheated gas, and enter the suction port of compressor A.

When the ambient temperature is 25°C, the non-azeotropic mixed working fluid used in the multi-temperature refrigerator is selected from the above-mentioned low boiling point working medium group and high boiling point working medium group. The function of the evaporation temperature of the low temperature evaporator is shown in Table 2 below:

Table 2:

project Mixture 1 mass concentration% Mixture 2 mass concentration% Mixture 3 mass concentration% Low boiling point working fluid 5 (propane) and 10 (pentafluoroethane) 10 (propane) and 25 (pentafluoroethane) 15 (propane) and 30 (pentafluoroethane) High boiling point working fluid 85 (butane) 65 (butane) 55 (butane)

Variation range of average evaporation temperature of low temperature evaporator (°C) -35～-20 -40～-25 -45～-28 Average evaporation temperature of high temperature evaporator (℃) -5 -10 -12

Embodiment 3: Referring to Fig. 3, there is a multi-temperature refrigerator with three-stage evaporating temperature and wherein the evaporating temperature of the primary evaporator can be adjusted within a certain range, including a refrigeration compressor A, a condenser B, a gas-liquid separator C, a condensing Evaporator D, first throttle valve F1 and second throttle valve F2, high temperature evaporator E1, low temperature evaporator E2, variable temperature chamber evaporator E3 and three-way flow distribution valves J1, J2. The device uses a two-element or multi-element non-azeotropic mixed working medium, and its cycle flow is: the high-pressure exhaust port of the refrigeration compressor A is connected to the condenser B, and the mixed refrigerant vapor is partially condensed in the condenser B to become a gas-liquid The two phases enter the gas-liquid separator C, and in the gas-liquid separator C, the gas-phase working medium containing more low-boiling point component refrigerants and the liquid-phase working medium containing more high-boiling point component refrigerants are separated, and the liquid phase After being throttled by the first throttle valve F1, the working fluid all enters the high-temperature evaporator E1; the gas-phase working fluid is condensed into a saturated or supercooled liquid by the condensing evaporator D, and then all enters the low-temperature evaporator E2 after being throttled by the second throttle valve F2 . When it is necessary to adjust the evaporation temperature of the variable compartment evaporator E3, the two three-way flow distribution valves J1 and J2 can be used to simultaneously adjust the volume of the mixed working fluid entering the variable temperature evaporator E3 from the high temperature evaporator E1 and the low temperature evaporator E2 Composition and flow rate, so that the evaporation temperature of variable temperature evaporator E3 has a large temperature change; all refrigerants are mixed before condensing evaporator D, and absorb heat in condensing evaporator D to become saturated or superheated gas, and enter compressor A suction port.

When the ambient temperature is 25°C, the non-azeotropic mixed working fluid used in the multi-temperature refrigerator is selected from the above-mentioned low boiling point working medium group and high boiling point working medium group. It can provide three different evaporation temperatures and also has the ability to adjust The function of the evaporation temperature of the variable temperature compartment evaporator is shown in Table 3 below:

table 3:

project Mixture 1 mass concentration% Mixture 2 mass concentration% Mixture 3 mass concentration% Low boiling point working fluid 15 (difluoromethane) 30 (difluoromethane) 45 (difluoromethane) High boiling point working fluid 85 (isobutane) 70 (isobutane) 55 (isobutane) Average evaporation temperature of low temperature evaporator (℃) -30 -33 -40 Average evaporation temperature of high temperature evaporator (℃) -3 -5 -10 The variation range of the average evaporation temperature of the variable temperature chamber evaporator (°C) -12～2 -15～0 -18～-5

Certainly, the low-boiling-point working fluid and the high-boiling-point working fluid in the above-mentioned embodiments can be selected within the scope of various high- and low-temperature working fluids given by the above-mentioned inventors, and within the range given by the present invention, the purpose of the present invention can be achieved .

It needs to be clarified that: Figures 1, 2, and 3 are the basic cycle flow diagrams of multi-temperature refrigerators that provide multi-stage evaporation temperatures based on self-cascading refrigeration cycles and have one-stage variable evaporation temperatures. If heat exchange equipment or Liquid storage equipment or rectification equipment to change the circulation process, or replace the three-way flow distribution valve by a combination of other control valves, so as to adjust the evaporation temperature of the evaporator in each chamber by adjusting the composition and flow of the mixed working medium in the evaporator The purpose also belongs to the protection scope of the present invention.

Claims (2)

1. A method for operating a multi-temperature refrigerator with variable evaporation temperature, characterized in that the multi-temperature refrigerator comprises: refrigeration compressor (A), condenser (B), gas-liquid separator (C), Condensing evaporator (D), first throttle valve (F1) and second throttle valve (F2), high temperature compartment evaporator (E1), low temperature compartment evaporator (E2) and three-way flow distribution valve (J1 ), the multi-temperature refrigerator can provide two different evaporating temperatures; when it is only necessary to change the storage temperature of the low compartment, the multiple non The adjustment of the components of the azeotropic mixture can realize the change of the evaporation temperature of the low-compartment evaporator (E2); the high-pressure exhaust port of the refrigeration compressor (A) is connected to the condenser (B), and the condenser (B) ), the mixed refrigerant vapor is partially condensed into a gas-liquid two-phase into the gas-liquid separator (C), and in the gas-liquid separator (C), the gas-phase working medium containing more low-boiling point component refrigerant and the gas-phase working medium containing more Separation of liquid-phase working medium for multiple high-boiling-point refrigerants, in which the liquid-phase working medium enters the high-temperature compartment evaporator (E1) after being throttled by the first throttle valve (F1); the gas-phase working medium passes through the condensing evaporator ( D) Condensed into saturated or supercooled liquid, all enter the low-temperature compartment evaporator (E2) after throttling by the second throttle valve (F2); When it is necessary to adjust the evaporation temperature of the low-temperature compartment evaporator (E2), adjust it through the three-way flow distribution valve (J1) at the outlet of the high-temperature compartment evaporator (E1), so that the flow from the high-temperature compartment evaporator (E1) Part or all of the high-temperature mixed refrigerant containing more high-boiling-point component refrigerant enters the low-temperature compartment evaporator (E2), thereby changing the low temperature by adjusting the composition and flow rate of the mixed refrigerant entering the low-temperature compartment evaporator (E2). The evaporating temperature of the compartment evaporator (E2); all the refrigerants are mixed before the condensing evaporator (D), and absorb heat in the condensing evaporator (D) to become saturated or superheated gas, and enter the suction of the refrigeration compressor (A) breath. 2. The method according to claim 1, wherein the multi-element zeotropic mixed refrigerant is composed of a low-boiling point refrigerant and a high-boiling point refrigerant, wherein the low-boiling point refrigerant comprises: tetrafluoromethane, ethylene, Ethane, monofluoroethylene, perfluoroethylene, trifluoromethane, monofluoromethane, perfluoroethane, carbon dioxide, difluoromethane, pentafluoroethane, trifluoroethane, monofluoroethane, propylene, propane, difluoroethane One of chlorofluoromethane, chloropentafluoroethane, perfluoropropane or a mixture of several of them; High boiling point working fluids include: propadiene, cyclopropane, 1,1,1,2-tetrafluoroethane, 1,1-difluoroethane, isobutane, n-butane, 1-butene, isobutene, 1,1,1,2,3,3,3-heptafluoropropane, 1,1,1,3,3,3-hexafluoropropane, 1,1,2,2,3-pentafluoropropane, tetrafluorochloro One of ethane or its mixture; The total mass concentration of the low-boiling point working substance is 15%-45%; the total mass concentration of the high-boiling point working substance is 55%-85%, and the sum of the mass concentrations of the two groups of substances is 100%.

Images