JP2001215065A - Freezing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a freezing system wherein a stable and smooth cooling operation can be resumed after a downtime of the operation. SOLUTION: A refrigerant supply pipe 2 is laid from the outlet of a compressor 1 to the inlet of a dry evaporator 8 in an air-conditioned room 6. A condenser 4 and a thermostatic expansion valve 5 are provided in the pipe 2. An evaporation pressure control valve 10 is provided in a refrigerant return pipe 9 which is laid from the outlet of the evaporator 8 to the suction port of the compressor 1. A bypass pipe 13 is laid astride the expansion valve 5, and a bypass open/close valve 14 is provided in a midpoint in the pipe 13. When the room temperature reaches a set temperature in an operation for raising the temperature of the air-conditioned room, the valve 14 is opened by a control circuit 15, and the valve 14 is closed after a predetermined time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry cooling type refrigeration system suitable for air conditioning in an environmental test apparatus or the like.

[0002]

2. Description of the Related Art A refrigeration system of an environmental test apparatus for performing various tests by changing the temperature in an environmental test chamber includes a dry cooling system, and the refrigeration system and a heater require a test chamber. It is configured to cool or heat to the temperature.

In such an environmental test apparatus, when the room temperature in the test chamber is changed from a low temperature to a high temperature, the evaporation pressure regulating valve provided on the suction side of the compressor in the refrigeration system is closed to evaporate the evaporation pressure in the evaporator. By raising
The cooling is stopped by the evaporator. At this time, since the evaporating pressure regulating valve is closed, the refrigerant does not flow into the refrigerant pipe, and therefore the pressure increases while the temperature of the refrigerant at the outlet side of the evaporator remains low.

As the expansion valve on the evaporator inlet side of the refrigeration system, a temperature-type expansion valve having a temperature sensing part for detecting the temperature and pressure of the refrigerant on the evaporator outlet side is generally used.

[0005] The expansion valve detects that the refrigerant temperature at the evaporator outlet side is low and the pressure is high, and determines that it is overcooled and closes. Furthermore, while the room temperature is being raised, the refrigerant does not flow due to the closing of the expansion valve, so the temperature of the refrigerant at the outlet side of the evaporator does not increase, and the expansion valve is not opened while judging that it is excessively cooled, and the room temperature is not increased. Even if the ascending is completed, it cannot be cooled, that is, the temperature of the test chamber cannot be lowered.

In order to solve the above-mentioned problem, conventionally, when the room temperature reaches a set temperature when the room temperature is raised, the evaporation pressure adjusting valve is forcibly opened, and the expansion valve is opened by lowering the evaporation pressure to open the refrigerant pipe. After the temperature of the temperature sensing portion is changed by flowing the refrigerant, the evaporation pressure adjusting valve is controlled again.

However, when the evaporating pressure regulating valve is forcibly opened, the evaporating pressure of the refrigerant in the evaporator cannot be temporarily controlled, so that the temperature control in the test chamber is disturbed.

[0008]

An object of the present invention is to provide a refrigeration system capable of stably and smoothly restarting a cooling operation after the cooling operation is stopped.

[0009]

In order to achieve the above object, a refrigeration system according to claim 1 of the present invention comprises a condenser provided in a refrigerant outgoing pipe extending from a discharge port of a compressor to an inlet of a dry evaporator in a room to be air-conditioned. ,
In a refrigeration system provided with a temperature-type expansion valve and having an evaporation pressure adjusting valve on a refrigerant return pipe extending from an outlet of the dry evaporator to an inlet of the compressor, a refrigerant and an expansion valve of the refrigerant forward pipe are provided. The other end of the bypass pipe with one end connected between it and the expansion valve of the refrigerant outgoing pipe is connected between the expansion valve and the evaporator. The configuration is such that a bypass opening / closing valve that is opened for a predetermined time when the temperature is reached is provided.

In a refrigeration system according to a second aspect of the present invention, a condenser and a thermal expansion valve are provided in a refrigerant outgoing pipe extending from a discharge port of a compressor to an inlet of a dry evaporator in a room to be air-conditioned.
In a refrigeration system having an evaporation pressure regulating valve in a refrigerant return pipe from an outlet of the dry evaporator to an inlet of the compressor, a bypass pipe having one end connected between a condenser and an expansion valve of the refrigerant forward pipe The other end of the bypass pipe is connected between the expansion valve of the refrigerant outgoing pipe and the evaporator, and a bypass open / close valve that is controlled to open and close based on a signal from the control circuit is provided in the middle of the bypass pipe, and the control circuit has a temperature control circuit. A temperature comparison circuit comprising a comparison circuit and a timer circuit, wherein the temperature comparison circuit compares a room temperature detected by a temperature sensor provided in the room to be air-conditioned with a preset temperature to increase the temperature in the room to be air-conditioned. When the room temperature reaches the set temperature, the temperature comparator turns on the timer circuit to open the bypass on-off valve, and when the timer circuit is turned off after a predetermined time, the bypass on-off valve is closed.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a refrigeration system according to the present invention will be described below in detail with reference to specific examples shown in the accompanying drawings. The other end of the refrigerant outward pipe 2 whose one end is connected to the discharge port of the compressor 1 is
It is connected via an oil separator 3, a condenser 4, and an expansion valve 5 to a dry evaporator 8 in an air conditioner 7 provided in a test room 6 which is a room to be air conditioned.

The other end of the refrigerant return pipe 9 having one end connected to the dry evaporator 8 is connected to the compressor 1 via an evaporation pressure regulating valve 10.
Connected to the suction port.

The expansion valve 5 is a temperature-type expansion valve, and its temperature sensing part 5a is connected to the refrigerant return pipe 9 near the evaporator outlet.
The end of a pressure equalizing pipe 5b for detecting the pressure of the refrigerant in the refrigerant return pipe 9 is also connected to the vicinity of the temperature sensing part of the refrigerant return pipe. In addition, the code | symbol 11 in a figure shows the heater of an air conditioner, and 12 has shown the fan.

In the middle of the refrigerant forward pipe 2, one end is connected between the condenser 4 and the expansion valve 5, and the other end is connected between the expansion valve 5 and the evaporator 8, so that the expansion valve 5 is provided, and a bypass opening / closing valve 14 is provided in the middle of the bypass pipe 13.

The bypass on-off valve 14 is opened for a predetermined time by a command from the control circuit 15 only when the temperature (room temperature) in the test chamber 6 reaches a preset temperature (set temperature) when raising the room temperature. However, it is closed during other cooling operations or when the cooling operation is stopped.

The control circuit 15 includes a temperature comparison circuit and a timer. The temperature comparison circuit compares a room temperature detected by a temperature sensor 16 provided in the test chamber 6 with a set temperature.
When the room temperature is equal to the set temperature during the operation of raising the room temperature, the timer is turned on by a signal from the temperature comparison circuit, the control circuit 15 opens the bypass on-off valve 14, and the control circuit 15 is turned off after a predetermined time. Closes the bypass on-off valve 14. Note that the time during which the timer is ON, that is, the time during which the bypass on-off valve 14 is kept open depends on various factors such as the capacity of the evaporator 8 and the room temperature in the test chamber 6.

Next, the operation of the refrigeration system according to the present invention configured as described above will be described. During the cooling operation, the bypass on-off valve 14 is closed, and the refrigerant from the compressor 1 flows into the evaporator 8 through the oil separator 3, the condenser 4, and the expansion valve 5 through the refrigerant forward pipe 2, and the blower The heat exchange with the room air flowing through the air conditioner 7 is performed by the air conditioner 12. Then, the refrigerant from the evaporator 8 is returned to the compressor via the evaporation pressure regulating valve 10 by the refrigerant outward pipe 9.

When raising the room temperature, the heater 11
In the refrigerating system, the evaporating pressure of the refrigerant in the evaporator 8 is increased by closing the evaporating pressure regulating valve 10 to suspend the cooling in the evaporator. At this time, the expansion valve 5 is closed by detecting the low temperature and high pressure of the refrigerant temperature at the outlet side of the evaporator 8 by the temperature sensing part 5a and the equalizing pipe 5b.

[0019] Thereafter, when the temperature of the test chamber 6 detected by the temperature sensor 16 reaches the set temperature T _H which is preset as shown in FIG. 2, the temperature comparator circuit of the control circuit 15 is a timer as ON The control circuit is a bypass on-off valve 14
The control circuit closes the bypass on-off valve 14 when the timer is turned off after a predetermined time t has elapsed.

At this time, the refrigerant in the refrigerant outgoing pipe 2 flows through the bypass pipe 13 and flows into the evaporator 8, and the refrigerant temperature in the evaporator and the refrigerant return pipe 9 at the outlet side rises and expands. The valve 5 is opened, and the cooling operation can be resumed. This state is maintained even when the room temperature is maintained at a high temperature, and the cooling operation is performed immediately upon receiving a cooling operation command from the outside.

[0021]

The refrigeration system according to the present invention is provided with a bypass pipe straddling the expansion valve in the middle of the refrigerant outgoing pipe. Therefore, even if the cooling operation is stopped and the temperature-type expansion valve is closed, the room to be conditioned is conditioned. When the temperature of the evaporator reaches the set temperature, the refrigerant flows through the bypass pipe to the evaporator, so that the refrigerant temperature at the evaporator outlet rises, the temperature type expansion valve is opened, and the cooling operation can be restarted immediately if necessary. In addition, there is no possibility that the cooling operation is disturbed by forcibly opening the evaporating pressure regulating valve in the refrigerant return pipe as in the conventional refrigeration system, and a stable cooling operation can be performed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of a refrigeration system according to the present invention.

FIG. 2 is a graph showing a relationship between a change in room temperature and opening / closing control of a bypass on-off valve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 2 Refrigerant forward pipe 3 Oil separator 4 Condenser 5 Thermal expansion valve 6 Test room 7 Air conditioner 8 Dry evaporator 9 Refrigerant return pipe 10 Evaporation pressure control valve 11 Heater 12 Blower 13 Bypass pipe 14 Bypass opening / closing valve 15 Control circuit 16 Temperature sensor

Claims (2)

[Claims] A condenser and a thermal expansion valve are provided in a refrigerant outgoing pipe extending from a discharge port of a compressor to an inlet of a dry evaporator in a room to be air-conditioned, and suction of the compressor from an outlet of the dry evaporator. In a refrigeration system having an evaporation pressure regulating valve at the refrigerant return pipe reaching the mouth, the other end of the bypass pipe having one end connected between the condenser and the expansion valve of the refrigerant outgoing pipe is connected to the expansion valve of the refrigerant outgoing pipe. A refrigeration system comprising a bypass opening / closing valve connected between the air conditioning unit and a bypass opening / closing valve in the middle of the bypass pipe, which is opened for a predetermined time when the temperature of the air conditioned room reaches a set temperature during an operation for raising the temperature of the air conditioned room. 2. A condenser and a temperature expansion valve are provided in a refrigerant outgoing pipe extending from a discharge port of a compressor to an inlet of a dry evaporator in a room to be air-conditioned, and suction of the compressor from an outlet of the dry evaporator. In a refrigeration system having an evaporation pressure regulating valve at the refrigerant return pipe reaching the mouth, the other end of the bypass pipe having one end connected between the condenser and the expansion valve of the refrigerant outgoing pipe is connected to the expansion valve of the refrigerant outgoing pipe. A bypass opening / closing valve that is connected and connected between the bypass pipe and the opening / closing valve that is controlled to open / close based on a signal from a control circuit in the middle of the bypass pipe; the control circuit includes a temperature comparison circuit and a timer circuit; Compares a room temperature detected by a temperature sensor provided in the air-conditioned room with a preset set temperature, and when the room temperature reaches the set temperature during the operation of raising the temperature in the air-conditioned room, the temperature comparison circuit The timer circuit is
A refrigeration system having a configuration in which the bypass on-off valve is opened after N times and the timer circuit is turned off after a predetermined time, and the bypass on-off valve is closed.