JPH11237126A - Refrigeration equipment for HFC refrigerant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve performance by optimizing a liquid injection flow rate corresponding to each refrigerant in a refrigeration system capable of using a plurality of HFC-based refrigerants, and to provide a refrigeration system capable of performing stable operation. Get control method. SOLUTION: In a refrigerating apparatus having a compressor, a condenser, a subcooler, and a liquid receiver, a cycle system is connected in order of a compressor, a condenser, a liquid receiver, and a supercooler, and a liquid injection pipe connection part is connected. The structure is provided after the subcooler. A controller is provided for controlling the liquid injection flow rate corresponding to each HFC-based refrigerant based on the discharge gas temperature. [Effect] In a refrigeration system that can use a plurality of HFC-based refrigerants, the liquid refrigerant after the supercooler is supplied to the compressor, and the performance is improved by optimizing the liquid injection flow rate according to the type of the refrigerant, and the stability is improved. Driving becomes possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for controlling a plurality of hydrofluorocarbotypes by a control method which enables stable operation control.
An object of the present invention is to obtain a refrigeration apparatus that can use an n (hereinafter abbreviated as HFC) -based refrigerant.

[0002]

2. Description of the Related Art As a conventional refrigerating apparatus, for example, as disclosed in Japanese Patent Application Laid-Open No. 5-322228, a refrigerating apparatus having a scroll compressor mounted thereon is driven by a pulse motor to an intermediate pressure section of the scroll compressor. Liquid refrigerant is introduced through an electronic expansion valve, which is a control valve that controls the opening (hereinafter, referred to as “
This is called liquid injection. In addition, there is known a scroll compressor which controls a discharge gas temperature of a scroll compressor.

[0003]

However, the above prior art has a problem that the opening and closing amount of the electronic expansion valve cannot be adjusted according to the type of the refrigerant. Also, R404
The HFC-based refrigerant for refrigeration equipment such as A, R507A, and R407C has a lower scroll compressor discharge gas temperature under the same conditions as compared to the conventional R22 and other such hydrochlorofluorocarbon (hereinafter abbreviated as HCFC) -based refrigerant. For this reason,
It is extremely important to control the liquid injection flow rate to an appropriate flow rate according to the type of the refrigerant and the operation state of the refrigeration system.

Accordingly, an object of the present invention is to provide a refrigeration system that can use a plurality of HFC-based refrigerants, by varying the opening of an electronic expansion valve depending on the temperature of gas discharged from a scroll compressor regardless of the type of refrigerant. The purpose is to optimize the liquid injection flow rate and improve the reliability by operating at a stable temperature.

[0005]

In order to achieve the above object, a refrigeration system for HFC refrigerant according to the present invention has the features described in each of the claims. In particular, the HFC-based refrigerant-compatible refrigeration apparatus according to the first aspect of the present invention includes a compressor, a condenser, a subcooler, a liquid receiver,
In the refrigeration system for an HFC-based refrigerant equipped with a refrigerant, HFC-based refrigerants such as R404A, R507A, and R407C are used as the refrigerant, and the discharge gas refrigerant compressed by the compressor is:
Via the condenser, the receiver, the subcooler in order,
A cycle system is configured to be sent to the low pressure side device, and a liquid injection pipe connecting the downstream pipe of the subcooler and the intermediate pressure chamber of the compressor is provided, and the liquid injection pipe is provided on the liquid injection pipe. An electronic expansion valve for varying the injection flow rate and a controller for controlling the liquid injection flow rate in accordance with the type of refrigerant used are provided.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an example of a basic refrigeration cycle of a refrigeration apparatus according to the present invention. In FIG. 1, I is an air-cooled integrated refrigeration apparatus, and II is a low-pressure side device, which are connected at piping connections 18 and 19 to form a refrigeration cycle.

1 is a scroll compressor, 2 is a condenser provided on the downstream side of the scroll compressor, and 3 is a supercooler integrated with the condenser 2. The gas refrigerant discharged from the scroll compressor 1 is cooled and condensed into a liquid refrigerant by the condenser 2 and the cooling fan 14, and the condensed liquid refrigerant is temporarily stored in the five liquid receivers, and thereafter, the liquid refrigerant is discharged. Only the structure is such that it is guided to the supercooler 3.

The supercooled liquid refrigerant passes through a dryer 9 that adsorbs moisture during the cycle and a sight glass 8 that is a viewing window for checking the flow of the refrigerant, and is transmitted from a solenoid valve 7, an expansion valve 6, and an evaporator 4. After evaporating in the low-pressure side device II and becoming gas refrigerant again, it is sucked into the scroll compressor 1 through the accumulator 13.

A liquid refrigerant pipe downstream of the subcooler 3 and an intermediate pressure chamber of the scroll compressor 1 are connected by a liquid injection pipe 10, and the liquid injection pipe 10 has an electronic expansion for controlling a liquid injection flow rate. A valve 11 is provided.

Further, the discharge gas temperature of the scroll compressor 1 is detected by a discharge gas temperature sensor 15 and is inputted to a controller 16, and each HF is stored in the controller 16 in advance.
The electronic expansion valve 1 is controlled so that the discharge gas temperature converges to a control temperature zone set to be compatible with the C-based refrigerant.
1 to control the injection flow rate of the liquid refrigerant into the intermediate pressure chamber of the scroll compressor 1.

When the load on the low-pressure side device II decreases and the suction gas pressure decreases, the low-pressure pressure cutoff device 17 installed on the suction side of the scroll compressor 1 operates, and the air-cooling integrated refrigeration device I stops. If the electronic expansion valve 1 before stopping,
1, the solenoid valve 12 provided in the middle of the liquid injection pipe 10 is closed to prevent the liquid refrigerant from flowing into the scroll compressor 1 during stoppage.

Thereafter, the load on the low-pressure side device II increases, and the suction gas pressure rises.
The low-pressure pressure shut-off device 17 installed on the suction side of the
When the air-cooled integrated refrigeration apparatus I resumes operation, the liquid injection flow rate is controlled based on the opening degree of the electronic expansion valve 11 before the stop. With the above-described control, it is possible to minimize the fully closing operation of the electronic expansion valve 11, and to improve the reliability of the electronic expansion valve 11.

FIG. 2 is a control flow chart showing a control method for varying the initial opening of the electronic expansion valve 11 according to the temperature detected by the discharge gas temperature sensor 15 when the power is turned on in the refrigerating apparatus of the present invention. FIG. 2 illustrates an example of a variable initial opening control method of the electronic expansion valve 11 for optimizing the liquid injection flow rate of the air-cooling integrated refrigeration apparatus I.

When the power is turned on, if the temperature detected by the discharge gas temperature sensor 15 of the air-cooled integrated refrigeration system I is higher than 30 ° C., the initial opening degree of the electronic expansion valve 11 is A, 0 ° C. to 30 ° C.
In this case, the initial opening degree of the electronic expansion valve 11 is B, and the opening degree of the initial electronic expansion valve 11 is lower than 0 ° C.

Here, A, B, and C are constants preset according to the capacity of the air-cooled integrated refrigeration system I and the type of refrigerant.
The opening degree is A>B> C.

The temperature detected by the discharge gas temperature sensor 15 is 30
When the temperature is higher than 0 ° C., the initial opening is set to A, and the opening is increased to prevent the discharge gas temperature from rising above the control temperature zone after starting, so that the scroll compressor 1 does not perform the heating operation. . When the temperature detected by the discharge gas temperature sensor 15 is lower than 0 ° C., the initial opening is set to C, and the opening is made small so that the discharge gas temperature after startup does not become too low.

When the temperature detected by the discharge gas temperature sensor 15 is in the range of 0 ° C. to 30 ° C., the initial opening is set to B between A and C. Thus, by changing the initial opening degree according to the detected temperature, stable liquid injection control can be performed at the time of startup.

FIG. 3 is a control flow chart showing a method for controlling the opening of the electronic expansion valve 11 for liquid injection in the refrigeration apparatus of the present invention. 1 and 3, an example of a method of controlling the opening degree of the electronic expansion valve 11 for controlling the discharge gas temperature by the discharge gas temperature sensor 15 for optimizing the liquid injection flow rate of the air-cooling integrated refrigeration apparatus I will be described.

The controller 16 installed in the air-cooled integrated refrigerating apparatus I is preliminarily input with control values for each of the refrigerants in order to be compatible with a plurality of HFC-based refrigerants. Before starting the operation of the device I, the refrigerant to be used is set by the controller 16. Thereafter, the power supply of the air-cooling integrated refrigeration system I is turned on, the low-pressure pressure shut-off device 17 returns, and the cooling operation is started, and at the same time, the opening control of the liquid injection electronic expansion valve 11 is started.

First, when the power is turned on, as described with reference to FIG. 2, the opening of the electronic expansion valve 11 is set to a preset initial opening, and liquid injection control is performed. At the same time, the scroll compressor 1 in operation of the air-cooled integrated refrigeration system I
The discharge gas temperature is detected by the discharge gas temperature sensor 15,
Input to the controller 16. The controller 16 controls the input discharge gas temperature Td so as to converge on a preset control temperature D corresponding to the used refrigerant.

In this case, the discharge gas temperature control temperature zone becomes the control temperature D ± 5 ° C. When the discharge gas temperature Td becomes higher than the control temperature zone upper limit temperature: D + 5 ° C., (1)
The number of pulses to the pulse motor for setting the opening of the electronic expansion valve 11 obtained by the equation is added to the initial opening, and (Td− (D + 5)) × α (1) The electronic expansion valve 11 is opened. The valve is controlled so that the discharge gas temperature Td converges on the control temperature zone.

In the equation (1), α is an air-cooled integrated refrigeration system I
Is a constant set in advance by the controller 16 according to the capacity and the type of refrigerant. After a predetermined time T has elapsed, the discharge gas temperature Td is detected again, and the control temperature zone D ± 5 is detected.
Check if it is within the range of ° C. At this time, if the temperature is lower than the control temperature zone lower limit value D-5 ° C., the liquid injection flow rate is too large. Therefore, the number of pulses obtained by the equation (2) is subtracted from the current number of pulses, and the opening of the electronic expansion valve 11 is performed. Close the valve.

((D−5) −Td) × α (2) Further, after a certain time T has elapsed, if the discharge gas temperature Td is within the control temperature range, the current electronic expansion valve 11 And the liquid injection control is performed.

By continuing the cooling operation, the load is reduced, and the low-pressure pressure cut-off device 17 is operated to activate the scroll compressor 1.
Is stopped, the opening of the electronic expansion valve 11 before the stop is maintained, and when the operation is started again, the control is restarted with the opening of the electronic expansion valve 11 before the stop.

[0025]

According to the present invention, the supercooling is ensured by connecting the cycle system in the order of the condenser, the liquid receiver, and the supercooler, and by connecting the liquid injection piping connection portion after the supercooler. It is possible to guide the liquid refrigerant sufficiently condensed even for the HFC-based refrigerant, which is difficult to perform, to the scroll compressor,
Regarding the discharge gas temperature control, by controlling the liquid injection flow rate by the electronic expansion valve corresponding to each HFC-based refrigerant, it is possible to provide a refrigeration apparatus that can support a plurality of HFC-based refrigerants, and to achieve stable operation in terms of temperature. Can improve reliability.

Further, by improving the control method of the electronic expansion valve installed in the liquid injection pipe so as not to perform the fully closing control as much as possible, the opening and closing operation of the electronic expansion valve is minimized, and the reliability of the electronic expansion valve is reduced. Performance can be improved.

[Brief description of the drawings]

FIG. 1 is a refrigeration cycle system diagram of a refrigeration apparatus showing one embodiment of the present invention.

FIG. 2 is a control flow chart showing a control method for varying the initial opening of the electronic expansion valve according to the temperature detected by a discharge gas temperature sensor when the power is turned on in the refrigeration apparatus of the present invention.

FIG. 3 is a control flow chart showing a liquid injection electronic expansion valve opening control method in the refrigeration apparatus of the present invention.

[Explanation of symbols]

I ... Air-cooled integrated refrigeration system II ... Low pressure side equipment 1 ... Scroll compressor 2 ... Condenser 3 ... Subcooler 4 ... Evaporator 5 ... Liquid receiver 6 ... Expansion valve 7 ... Solenoid valve 8 ... Sight glass 9 ... Dryer 10 ... Liquid injection piping 11 ... Electronic expansion valve 12 ... Solenoid valve 13 ... Accumulator 14 ...・ Cooling fan 15 ・ ・ ・ Discharge gas temperature sensor 16 ・ ・ ・ Controller 17 ・ ・ ・ Low pressure pressure cut-off device 18,19 ・ ・ ・ Piping connection

Claims (5)

[Claims] 1. An HFC-based refrigerant refrigeration system including a compressor, a condenser, a supercooler, and a liquid receiver, wherein the refrigerant is H404A, R507A, R407C, or the like.
Using a FC-based refrigerant, the discharge gas refrigerant compressed by the compressor, via the condenser, the liquid receiver, the subcooler in order, is configured to a cycle system to be sent to the low-pressure side equipment. And, a liquid injection pipe connecting the downstream pipe of the subcooler and the intermediate pressure chamber of the compressor is provided, and an electronic expansion valve for changing the liquid injection flow rate on the liquid injection pipe, A refrigeration system compatible with HFC-based refrigerants, further comprising a controller for controlling the liquid injection flow rate according to the type of refrigerant used. 2. The controller according to claim 1, wherein the controller controls the opening of the electronic expansion valve for liquid injection based on a discharge gas temperature detected by a discharge gas temperature sensor provided for detecting a discharge gas temperature of the compressor. The refrigeration system for an HFC-based refrigerant according to claim 1, wherein the refrigeration unit controls the liquid injection flow rate by adjusting. 3. The controller according to claim 1, wherein the controller is configured to change an initial opening of the electronic expansion valve for liquid injection according to a temperature detected by the discharge gas temperature sensor when the power of the refrigeration system for HFC refrigerant is turned on. The HF according to claim 1, wherein the HF has a simple control method.
Refrigeration system for C-based refrigerant. 4. The controller according to claim 1, wherein the controller controls an initial opening degree and an opening / closing amount of the electronic expansion valve for liquid injection.
A control system that varies according to the type of HFC-based refrigerant used in the HFC-based refrigerant-compatible refrigeration apparatus and is capable of converging the discharge gas temperature of the compressor to an appropriate range. The refrigeration system for an HFC-based refrigerant according to any one of claims 1 to 3. 5. The controller according to claim 1, wherein the controller does not fully close the electronic expansion valve when the operation of the refrigeration system corresponding to the HFC-based refrigerant is stopped by the operation of the low-pressure pressure shut-off device by controlling the opening and closing of the electronic expansion valve for liquid injection. The refrigeration system for an HFC-based refrigerant according to any one of claims 1 to 4, further comprising a control system for maintaining the opening before the stop and restarting the control at the opening before the stop when restarting. .