JPS62228839A - Refrigerator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a refrigeration system using a non-azeotropic mixed refrigerant.

[Conventional technology]

A conventional refrigeration system using a non-azeotropic mixed refrigerant is disclosed in, for example, Japanese Patent Application Laid-Open No. 58-210447.

FIG. 7 is a block diagram of a refrigeration cycle when such a non-azeotropic mixed refrigerant is used in a refrigerator-freezer. In the figure, 1 is a compressor, 2 is a condenser, 3 is a capillary, 4 is an evaporator for the freezer compartment, and 5 is an evaporator for the refrigerator compartment. It constitutes a cycle.

In the refrigerator-freezer configured as described above, the compressor 1
The high-temperature, high-pressure refrigerant gas compressed by the condenser 2 is condensed in a high-pressure state by the condenser 2, and this high-pressure liquefied refrigerant is depressurized while passing through the capillary 3, and is then sent to the next stage, the evaporator 4 for the freezer compartment and the evaporator for the refrigerator compartment. Flows into vessel 5 in order. The refrigerant gas evaporated by the endothermic action in the two evaporators 4.5 returns to the compressor 1, is compressed again, and is sent to the condenser 1.

In such a refrigeration cycle, the refrigerant includes, for example, a low boiling point component R22 (boiling point -40.75°C) and a high boiling point component R114 (boiling point 3.77°C), which have a boiling point difference of about 44°C. When a boiling mixture refrigerant is used, in the evaporation process, as shown by reference numeral 10.11 in the Molière diagram in Figure 8, the liquid refrigerant containing a large amount of R22 evaporates first, so its evaporation temperature is low; Next, as the liquid refrigerant containing a large amount of R114 gradually evaporates, its evaporation temperature increases.

In the above evaporation process, the low temperature region IO is used for the evaporator 4 for the freezer compartment, and the high temperature region 11 is used for the evaporator 5 for the refrigerator compartment. Since the indoor evaporator 4 can be used, and the refrigerator compartment evaporator 4 can be used in the refrigerator compartment at an evaporation temperature suitable for that temperature, the refrigeration effect is improved compared to systems that use a single refrigerant (for example, R12). can.

In the Molière diagram of FIG. 8, reference numeral 6 indicates an equimixture line, 7 indicates a compression region, 8 indicates a condensation region, and 9 indicates a depressurization region.

[Problem that the invention seeks to solve]

With the conventional refrigeration equipment described above, the effects described above may be obtained under optimal operating conditions, but
In reality, the refrigeration cycle cannot maintain optimal operation because operating conditions such as changes in outside air temperature and changes in the component ratio of the non-azeotropic refrigerant mixture change.

For example, in the refrigeration cycle as described above, when operating conditions change, if the liquid refrigerant is not completely evaporated in the evaporator and returns to the compressor, the compressor may be damaged.

On the other hand, if the liquid refrigerant completely evaporates in the evaporator and returns to the compressor as a large amount of heated vapor, the compression performance of the compressor may deteriorate, causing the problem that optimal operating conditions cannot be maintained. Ta.

This invention was made to solve the above-mentioned problems, and allows the refrigeration cycle to always operate optimally even when operating conditions such as changes in the component ratio of the non-azeotropic mixed refrigerant and changes in outside temperature change. The purpose is to obtain a refrigeration system with

[Means for solving problems]

The refrigeration system according to the present invention includes a liquid receiver provided between a condenser and a pressure reducing device, detects the pressure and temperature in the liquid receiver to calculate a component ratio of a non-azeotropic mixed refrigerant, and calculates the component ratio of a non-azeotropic mixed refrigerant. It is equipped with arithmetic control means that calculates the degree of heating of the refrigerant sucked into the compressor based on the pressure and temperature at the outlet of the evaporator, and controls the degree of heating by the degree of opening and closing of the pressure reducing device. .

[For production]

In this invention, the calculation control means controls the degree of opening and closing of the pressure reducing device so that the degree of heating of the refrigerant to the compressor, which is calculated from the component ratio of the non-azeotropic refrigerant mixture and the pressure and temperature at the outlet of the evaporator, becomes an optimum value. This enables optimal operation of the refrigeration cycle without being affected by changes in operating conditions.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the refrigeration system according to the present invention, in which symbol (2) is a compressor, 2 is a condenser connected to the discharge side of the compressor 1, and 12 is a receiver connected to the outlet side of the condenser 2. 13 is a pressure reducing device connected to the outlet side of the liquid receiver 12 and is capable of adjusting the opening/closing degree; 14 is an evaporator in which the pressure reducing device 13 is connected between the suction side of the compressor 1, and these are connected in series by piping. A refrigeration cycle is constructed by connecting the refrigerant to the refrigeration cycle, and a non-azeotropic mixed refrigerant consisting of, for example, a high boiling point component R114 and a boiling point component R22 is sealed in the refrigeration cycle.

The liquid receiver 12 is provided with a pressure detector 15 for detecting the saturation pressure P1 of the internal refrigerant, and a temperature detector 16 for detecting the saturation temperature T1. The signal is input to the arithmetic control circuit 17.

Further, at the outlet of the evaporator 14, a pressure detector 18 for detecting the pressure P2 of the refrigerant sucked into the compressor and a temperature T2
A temperature detector 19 is provided to detect the temperature, and detection signals from these detectors 18 and 19 are input to the arithmetic control circuit 17.

The arithmetic control circuit 17 has a function of calculating the component ratio η of the non-azeotropic mixed refrigerant based on the saturation pressure P1 and saturation temperature T1 from the detector 15.16, and the function of calculating the component ratio η of the non-azeotropic mixed refrigerant and the refrigerant component ratio η and the detector 18.19. A function to calculate the degree of heating S-H of the suction refrigerant to the compressor 1 based on the pressure P2 and temperature T2 from and an arithmetic control circuit 1
A control output signal from 7 is supplied to a driver 20 for adjusting the opening/closing degree of the pressure reducing device 13.

Next, the operation of this embodiment configured as described above will be explained.

The high-temperature, high-pressure refrigerant gas compressed by the compressor 1 is condensed in a high-pressure state by the condenser 2, and this high-pressure liquefied refrigerant flows into the receiver 12. The refrigerant that has flowed into the liquid receiver 12 is further reduced in pressure by a pressure reducing device 13, and then enters the evaporator 14, and the refrigerant gas evaporated by its endothermic action returns to the compressor 1, completing the cycle.

Next, the operation of the arithmetic control circuit 17 will be explained based on the flowchart shown in FIG.

In the above cycle, the refrigerant in the liquid receiver 12 becomes a saturated liquid due to the action of the liquid receiver 12, so that the pressure P l +temperature T1 in the liquid receiver 12 becomes the saturated pressure and the saturated temperature, respectively.

When the operation of the arithmetic control circuit 17 is started, first, in step SI, the saturation pressure P of the refrigerant in the liquid receiver 12 detected by each of the detectors 15 and 16 is determined.

and saturation temperature T into the arithmetic control circuit 17, and based on the detected pressure P1 and the detected temperature T, the component ratio η (weight fraction of low boiling point component or high boiling point component) of the non-azeotropic mixed refrigerant is determined.
is calculated from equation (1) (step 32).

η=F (PI ・TI) ・・・・・・・・・ (
1) However, F: constant In the next step S3, the pressure P2 and temperature T2 of the refrigerant at the evaporator outlet detected by the detectors 18 and 19 are taken into the calculation control circuit 17, and the process moves to the next step S4 to calculate η and P
g and the saturation temperature T.

Execute the calculation. That is, the arithmetic control circuit 17 calculates (2) based on the component ratio η and pressure PR calculated by the above equation (1).
By executing the equation, the saturation temperature T of the non-azeotropic mixed refrigerant at a pressure of 22 is calculated.

T = G (pg ・η) ・・・・・・・・・ (
2) However, G: a constant. Then, in the next step S5, the temperature T2 obtained from the above equation (2) and the temperature T2 at the outlet of the evaporator detected by the detector 19 are used to calculate the The heating degree 5-H (difference between T2 and TE) of the azeotropic refrigerant mixture is calculated.

Generally, there is a third difference between the refrigeration capacity and COP (coefficient of performance) of the refrigeration cycle and the suction refrigerant heating degree S-H of the compressor l.
There is a relationship shown in the figure, and at a certain heating degree, the refrigeration capacity and co
p becomes maximum.

Therefore, it is determined in step S6 whether the heating degree determined by the above equation (2) is the optimum value that maximizes the refrigerating capacity and cop of the refrigerating cycle. When it is determined that the value is the optimum value, the process proceeds to the end step, and when it is determined that the value is not the optimum value, the process proceeds to step S7 and the opening/closing degree changing process of the pressure reducing device 13 is executed.

That is, a control command is sent from the arithmetic control circuit 17 to the driver 20, and the driver 20 is operated to adjust the opening/closing degree of the pressure reducing device 13 so that the heating degree S-H becomes an optimum value.

By repeating the above operations, the refrigeration cycle can be operated optimally even if the operating conditions change.

In addition, FIG. 4 is a characteristic diagram showing the relationship between the refrigerant saturation temperature and the low boiling point component weight fraction η, and FIG. 5 is a characteristic diagram showing the relationship between the refrigerant saturation temperature and the R22 weight fraction in steam. It is a diagram.

FIG. 6 shows another embodiment of the refrigeration system of the present invention.

In the figure, the same symbols as in Figure 1 represent the same parts,
The difference from FIG. 1 is that a capillary 21 is provided between the condenser 2 and the receiver 12.

The reason for providing the capillary 21 is to prevent the pressure PI + temperature T1 in the receiver 12 from reaching the saturated pressure and saturated temperature, respectively, when the refrigerant at the outlet of the condenser 2 becomes a complete liquid due to supercooling. By reducing the pressure of the liquid refrigerant from the condenser 2 in the capillary 21, saturated liquid flows into the receiver 12. Therefore, the refrigerant is in the condenser 2
Even if the liquid is completely supercooled, the pressure P and temperature T1 in the liquid receiver 12 become the saturated pressure and the saturated temperature, respectively, and the refrigeration cycle can be operated optimally as in FIG. 1.

〔Effect of the invention〕

As described above, according to the present invention, the opening/closing degree of the pressure reducing device is controlled so that the degree of suction heating of the compressor becomes an optimum value. There is an effect that the refrigeration cycle can always be operated optimally even if operating conditions change due to changes in outside air temperature, etc.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an example of a refrigeration system according to the present invention, FIG. 2 is a flowchart for explaining the operation of the present invention, FIG. 3 is a diagram showing the relationship between heating degree, refrigerating capacity, and COP, and FIG. 5 and 5 are diagrams showing the relationship between refrigerant saturation temperature and component weight ratio, FIG. 6 is a circuit diagram showing another embodiment of the refrigeration system of the present invention, and FIG. 7 is a circuit diagram of a conventional refrigeration system. , FIG. 8 is a Moliere diagram of a non-azeotropic mixed refrigerant. l...Compressor, 2...Condenser, 12...Liquid receiver,
13... pressure reducing device, 14... evaporator, 15.18.
...Pressure detector, 16.19...Temperature sensor, 17.
... Arithmetic control circuit, 21... Capillary. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (2)

[Claims] (1) In a refrigeration cycle in which a compressor, a condenser, a pressure reducing device, and an evaporator are connected in sequence and a non-azeotropic mixed refrigerant consisting of a low boiling point component and a high boiling point component is used as the refrigerant, the space between the condenser and the pressure reducing device is is provided with a liquid receiver, and is provided with a detector that detects the saturation pressure and saturation temperature in the liquid receiver, and is provided with a detector that respectively detects the refrigerant pressure and temperature at the outlet of the evaporator, and further includes a detector that detects the refrigerant pressure and temperature at the outlet of the evaporator. Calculate the component ratio of the non-azeotropic mixed refrigerant based on the saturation pressure and saturation temperature in the liquid receiver detected by the detector, and based on this component ratio and the pressure and temperature at the outlet of the evaporator detected by the detector. A refrigeration system comprising arithmetic control means for calculating the degree of heating of the refrigerant sucked into the compressor, and controlling the magnitude of the degree of superheating by the opening/closing degree of the pressure reducing device. (2) The refrigeration system according to claim 1, wherein the refrigerant inlet of the liquid receiver is equipped with a capillary.