JPH04186064A - Binary refrigerating cycle - Google Patents

Abstract

PURPOSE:To make energy saving possible by a method wherein a plurality of temperature type expansion valves which correspond with different refrigerating capacities are provided at high temperature sides and low temperature sides for each refrigerating cycle, and the expansion valves are switched in response to the variation of refrigerating capacities by inverter control of a compressor. CONSTITUTION:A most suitable refrigerating capacity 24 is obtained by changing the discharge quantity 25 of a compressor by controlling the compressor operation frequency in response to load 23 of an evaporator 18, using refrigerating scroll compressors 3, 4 by inverter control. That is, when the load 23 of the evaporator decreases, the refrigerating capacity 24 decreases, and when the refrigerating capacity 24 becomes lower than a switching value 26, temperature type automatic expansion valves 8, 9, 16, 17 are switched from ones 8, 16 which have larger corresponding refrigerating capacity to one 9, 17 which have smaller corresponding refrigerating capacity by solenoid valves 6, 7, 14, 15. Also, when the load 23 increases, the refrigerating capacity 24 increases, and the temperature type automatic expansion valves 8, 9, 16, 17 are switched. By this method, the efficiency of the binary refrigerating cycle is improved, and energy saving can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a dual refrigeration cycle controlled by an inverter in a thermal shock testing device or the like.

[Conventional technology]

Conventionally, there is no binary refrigeration cycle that uses inverter control, and there is also no example of controlling switching of an expansion valve using it.

[Problem to be solved by the invention]

In the conventional technology, inverter control of a binary refrigeration cycle cannot be put to practical use because there is no temperature-type automatic □ expansion valve that can follow changes in refrigeration capacity due to changes in the discharge amount of the compressor. There wasn't.

The purpose of the present invention is to put into practical use a dual refrigeration cycle controlled by an inverter by switching and using a thermostatic automatic expansion valve within a range that can follow changes in refrigeration capacity;
The purpose is to provide an energy-saving dual refrigeration cycle.

[Means to solve the problem]

In order to achieve the above objective, a plurality of thermostatic expansion valves with different corresponding refrigeration capacities are installed in each refrigeration cycle on the high temperature side and the low temperature side. The expansion valve used can be switched.

[Effect]

In a dual refrigeration cycle controlled by an inverter, the refrigeration capacity is variable by frequency control of the compressor, but since a single thermostatic expansion valve cannot cover this range of changes in refrigeration capacity, an expansion valve is applied to this range. It is divided into parts within the range of refrigeration capacity, and the divided number of expansion valves are used in parallel and operated by switching with a solenoid valve. In response to changes in evaporation temperature, each expansion valve is automatically and independently controlled.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. FIG. 1 is a system diagram of the dual refrigeration cycle of the present invention.
Fig. 2 shows the refrigerating capacity of the binary refrigeration cycle of the present invention and the corresponding range of the refrigerating capacity of the thermostatic expansion valve, and Fig. 3 shows the frequency control of the compressor and expansion valve switching of the binary refrigeration cycle of the present invention. A control operation diagram is shown.

In FIG. 1, the binary refrigeration cycle consists of high temperature side refrigeration cycle 1. It consists of a low temperature side refrigeration cycle 2. The high temperature side cycle 1 includes an inverter-controlled refrigeration scroll compressor 3. Condenser 5. Expansion valve for large cycle capacity 8. Expansion valve for small refrigeration capacity9. Switching solenoid valve 6, 7. It consists of a cascade capacitor 1o. The low temperature side refrigeration cycle 2 includes an inverter-controlled refrigeration scroll compressor 4. Oil separator 11. Relief valve 12. Expansion tank 13. Cascade capacitor 10. Expansion valve for small refrigeration capacity 16° Expansion valve for small refrigeration capacity 17. It consists of switching solenoid valves 14, 15 and an evaporator 18. The cascade condenser 10 is an evaporator of the high temperature refrigeration cycle 1.

It also serves as a condenser for the low-temperature refrigeration cycle 2 and functions as a heat exchanger.

FIG. 2 shows the relationship between the refrigerating capacity and the discharge amount of the compressor and the applicable range of the expansion valve according to the present invention. There is a range 19 and a compressor discharge amount range 21 corresponding thereto.

Furthermore, there is a refrigerating capacity range 20 of the small refrigerating capacity expansion valves 9 and 17, and a compressor discharge amount range 22 corresponding thereto.

Next, the operation of this embodiment will be explained with reference to FIG.
The binary refrigeration cycle of the present invention uses refrigeration scroll compressors 3 and 4 controlled by an inverter. The optimum refrigerating capacity 24 is obtained by changing the amount 25. However, the temperature-type automatic expansion valve has a limited range of refrigerating capacity.

Therefore, the temperature type automatic expansion valves 8, 9, 16, and 17 are used to switch according to the refrigerating capacity. When the load 25 of the evaporator 18 decreases, the refrigerating capacity 24 decreases, and when it falls below the switching value 26, the thermostatic automatic expansion valves 8°9. ,17
It is switched to and fro by solenoid valves 6,7°14.15.

Conversely, when the load 23 increases, the refrigerating capacity 24 increases, and the thermostatic automatic expansion valves 8, 9, 16, and 17 are switched. However, the change in refrigerating capacity is caused by the temperature-type automatic expansion valve 8,9°16.
If the applicable range is 17 (2 for 19°20 in Figure 2)
1.22) No switching occurs.

In addition, in this embodiment, two temperature-type automatic expansion valves are used for switching, but depending on the corresponding refrigeration capacity, the number of expansion valves can be increased to three, four or more, and fine switching can be performed using two or more temperature-type automatic expansion valves. Changes in the refrigerating capacity of the original refrigerating cycle can be stabilized.

As described above, according to this embodiment, the expansion valve can follow changes in the refrigerating capacity due to the use of an inverter in the binary refrigeration cycle, thereby making it possible to put the binary refrigeration cycle into practical use under inverter control.

〔Effect of the invention〕

According to the present invention, a binary refrigeration cycle controlled by an inverter can be put into practical use, and the efficiency of the binary refrigeration cycle is improved, resulting in an increased energy saving effect.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of a refrigeration cycle according to an embodiment of the present invention, and Fig. 2 is a diagram showing the relationship between the compressor discharge amount and refrigeration capacity in a binary refrigeration cycle according to an embodiment of the present invention, and the selection of expansion valves that match the relationship. The characteristic diagram, FIG. 3, is a time chart of an embodiment of the present invention. 1... High temperature side refrigeration cycle, 2... Low temperature side refrigeration cycle, 3, 4... Inverter controlled refrigeration scroll compressor, 5... Condenser, 6, 7, 14. 15... Solenoid valve , 8.16...Temperature-type automatic expansion valve for low refrigeration capacity, 9゜17...Temperature-type automatic expansion valve for small refrigeration capacity, 10...
Power skate capacitor, 11... Oil separator, 12... Relief valve, 13... Expansion tank, 1
8...Evaporator, 19...Refrigerating capacity Okawa temperature-type automatic expansion valve applicable refrigerating capacity range, 2o...Refrigerating capacity range applicable to temperature-type automatic expansion valve for small refrigerating capacity, 21...Refrigerating capacity required temperature Compressor discharge amount range to which a type automatic expansion valve is applicable, 22... Compressor discharge amount range to which a temperature type automatic expansion valve for small refrigeration capacity is applicable, 23
...Evaporator load, 24...Refrigerating capacity, 25...Compressor discharge amount, 26...Switching value.

Claims (1)

[Claims] 1. In a binary refrigeration cycle using an inverter-controlled compressor, a plurality of pressure reducing mechanisms with different refrigeration capacities are provided in the refrigeration cycles on the low temperature side and high temperature side, respectively, and the refrigeration capacity of the compressor is A two-way refrigeration cycle is characterized in that it responds to changes in the pressure by switching the pressure reduction mechanism.