JPH0468263A - Refrigerating device - Google Patents

Abstract

PURPOSE:To prevent pressure decrease in the low pressure side and realize a stable running, even though a pressure should decrease in the high pressure side, by opening an electromagnetic valve and making a part of gas discharged from a compressor flow directly into an evaporator when a pressure in low pressure side becomes below a set value of a pressure detector in low pressure side. CONSTITUTION:Piping 2 which is used to connect a compressor 1 and an air-cooled condenser 3 and piping 8 which is used to connect a throttle device and an evaporator 9 are connected with piping 15 provided with an electromagnetic valve 14 in the middle way, and a part of a gas discharged from the compressor 1 is sent to the evaporator 9. When the temperature of cooled air decreases, the pressure in high pressure side can not be kept ever by stopping one of the condensers 4, 5, thereby the electromagnetic valve 14 is opened by the pressure detector 16 in the low pressure side under such running condition that the pressure in low pressure side decreases to the degree to freeze the evaporator 9. When the electromagnetic valve 14 is opened, a part of refrigerant gas discharged from the compressor 1 flows into an evaporator 9 through a pipe 15 and the electromagnetic valve 14. The refrigerant which flows through a throttle device 7 is reduced and the pressure in low pressure side is increased by the decrease in cooling capacity. The decrease in pressure loss of throttle device and the flowing of the gas with large entropy discharged from the compressor into the evaporator 9.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a refrigeration system that operates stably even when the temperature of a heat medium (air, water, etc.) that cools a condenser decreases, that is, even in winter. Regarding.

[Conventional technology]

In a refrigeration system that performs cooling operation throughout the year, when the temperature of the heat medium (air, water, etc.) for cooling the condenser decreases in winter, the pressure on the high pressure side of the refrigeration cycle decreases, and the pressure on the low pressure side also decreases, so the high pressure In order to maintain the low-pressure side pressure by maintaining the side pressure, the following method is used to reduce the flow rate of the heating medium.

That is, in an air-cooled refrigeration system, the rotational speed of the condenser blower is reduced, or in a system with a plurality of blowers, some of the blowers are stopped.

In a water-cooled refrigeration system, this method involves reducing the flow rate of condenser cooling water.

In addition, related to this type of equipment, for example, Japan Refrigeration Association Cotton, Refrigeration and Air Conditioning Handbook Basic Edition (198
1 year) listed on pages 346 to 349.

[Problem to be solved by the invention]

The above conventional technology is a method of preventing a drop in the pressure on the low pressure side by maintaining the pressure on the high pressure side, and there is no problem as long as the pressure on the high pressure side is maintained reliably. However, for example, in a refrigeration system with an air-cooled condenser, During extremely cold seasons or strong winds at low temperatures, the high-pressure side pressure may not be maintained even if the condenser blower is stopped. Also, even if the refrigeration equipment has a water-cooled condenser,
The same applies when the cooling water temperature is extremely low. If the pressure on the high-pressure side decreases extremely like this, the capacity of the throttling device decreases, and the pressure on the low-pressure side also decreases. Especially when the temperature of the cooled fluid cooled by the evaporator is low, the pressure on the low-pressure side decreases even more. Pressure decreases. In addition, the dimensions as a drawing device,
In a refrigeration system that uses a capillary tube with a fixed shape, there is a limit to the controllability of the capillary tube, and this tendency is exacerbated.

A decrease in the pressure on the low pressure side leads to a decrease in the evaporation temperature of the evaporator, and in refrigeration equipment that cools air, frost buildup occurs on the evaporator, and the heat transfer performance decreases due to this frosting, which further increases the low pressure side pressure. Operation becomes impossible due to pressure drop, frost growth on the evaporator, and complete freezing.

In addition, in refrigeration equipment that cools water, water freezes on the surface of the evaporator heat transfer tube that cools the water, and this freezing reduces heat transfer performance, further reducing the low pressure side pressure, and furthermore, the evaporator completely freezes. cause.

An object of the present invention is to prevent the low pressure side pressure from decreasing even when the high pressure side pressure decreases, thereby enabling stable operation.

[Means to solve the problem]

In order to achieve the above object, the present invention supplies a portion of the discharge gas of the compressor directly to the evaporator under conditions where the low pressure side pressure drops to a pressure corresponding to the evaporation temperature such as when the evaporator freezes during operation. Let it flow into the inlet.

Specifically, a low-pressure side pressure detection device detects when the low-pressure side pressure has dropped to a pressure that would cause the evaporator to freeze, and a solenoid valve is installed to bypass a portion of the compressor discharge gas to the condenser and throttle device. By opening the solenoid valve of the provided piping, the water flows directly into the evaporator.

A drop in pressure on the low side that would cause the evaporator to freeze.

Since this is caused by an extreme drop in the pressure on the high pressure side, a high pressure side pressure detection device is used instead of the low pressure side pressure detection device, the drop in high pressure side pressure is detected by the high pressure side pressure detection device, and the solenoid valve is opened. You can also do it.

In addition, since the extreme drop in pressure on the high pressure side is due to the temperature drop of the condenser cooling fluid during extremely cold periods, in place of the high pressure side pressure detection device, in systems equipped with air-cooled condensers, condenser cooling air temperature detection is used. If the device is equipped with a water-cooled condenser, a condenser cooling water inlet temperature detection device may be used instead.

Furthermore, when both the low-pressure side pressure detection device and the high-pressure side pressure detection device, or the condenser cooling air temperature detection device and the condenser cooling water inlet temperature detection device that replaced the high-pressure side pressure detection device, both reach the set value. If the solenoid valve is configured to open, more reliable control can be achieved.

[Function] As described above, even if the low pressure side pressure drops to a pressure that freezes the evaporator, a portion of the discharged gas from the compressor bypasses the condenser and throttling device and flows directly into the evaporator. In this case, the amount of refrigerant passing through the condenser and throttle device is reduced by the bypass amount, resulting in a decrease in cooling capacity, a decrease in pressure loss in the throttle device, and a lower pressure side than the inlet of the compressor discharge gas, which has a large enthalpy, to the evaporator. The pressure increases and can prevent the evaporator from freezing.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. High-temperature, high-pressure refrigerant gas discharged from the compressor 1 passes through a pipe 2 and enters an air-cooled condenser 3. The refrigerant gas that has entered the air-cooled condenser 3 is cooled and condensed by air from the condenser blowers 4 and 5. The condensed liquid refrigerant passes through a pipe 6, is depressurized by a throttle device 7, passes through a pipe 8, and enters a heat transfer tube IO of an evaporator 9. The refrigerant that has entered the heat exchanger tube 10 enters through the water inlet 11 and then through the water outlet 1.
2, the water that comes out takes heat, evaporates, exits the evaporator 9, passes through the pipe 13, and returns to the compressor 1. Condenser blower device 4,
5 detects the cooling air temperature or the high pressure side pressure (not shown) in order to maintain the high pressure side pressure when the temperature of the cooling air decreases and the high pressure side pressure of the refrigeration cycle decreases.
stop the individual.

The above is the conventional refrigeration cycle.

However, in this refrigeration cycle, when the temperature of the cooling air is low, such as during a severe cold season, or when there is strong wind, the high pressure side pressure cannot be maintained, and the low pressure side pressure also decreases accordingly. A decrease in the pressure on the low pressure side causes a decrease in the evaporation temperature of the refrigerant in the evaporator heat transfer tube 10. This evaporation temperature becomes lower1, e.g. -10℃
When the pressure drops to a certain level (2.6 kg/cdG on the low pressure side), the water side surface of the evaporator heat transfer tube 10 freezes. In such a state, the heat transfer performance of the heat transfer tube 10 is inhibited, and the pressure on the low pressure side further decreases, which causes ice to grow and completely freeze.
causing damage to the evaporator. For this reason, the refrigeration cycle can generally only be operated up to a cooling air temperature of about 5°C.

In the refrigeration cycle of the present invention, a pipe 2 connecting a compressor 1 and an air-cooled condenser 3 and a pipe 8 connecting a throttle device 7 and an evaporator 9 are connected by a pipe 15 having a solenoid valve 14 in the middle. A part of the discharged gas can be guided to the evaporator 9.

Under operating conditions where the cooling air temperature drops and the high-pressure side pressure cannot be maintained even if one of the blowers 4 and 5 is stopped, and therefore the low-pressure side pressure drops to a pressure that freezes the evaporator, the low-pressure side pressure is detected. Device 16 opens solenoid valve 14 . When the electromagnetic valve 14 is opened, a part of the refrigerant gas discharged from the compressor 1 passes through the pipe 15° and the electromagnetic valve 14 and flows into the evaporator 9.

With this configuration, the air-cooled condenser 3. A decrease in cooling capacity due to a decrease in the flow rate of refrigerant passing through the expansion device 7,
The pressure on the low pressure side increases due to the reduction in pressure loss of the throttle device and the flow of compressor discharge gas with a large enthalpy into the evaporator 9.

Since the decrease in the pressure on the low pressure side is accompanied by the decrease in the pressure on the high pressure side, a high pressure side pressure detection device 17 shown by a broken line may be used instead of the low pressure side pressure detection bag W116 in FIG.

Further, since the decrease in the high pressure side pressure is due to a decrease in the cooling air temperature, a cooling air temperature detection device 18 shown by a broken line can also be used. Furthermore, the low pressure side pressure detection device 16
When both the high-pressure side pressure detection device 17 or the cooling air temperature detection device 18 reach the set value, the solenoid valve 14
It can also be configured to open.

In this embodiment, an evaporator for cooling water is used, but the same applies when an evaporator for cooling air is used. Further, although an air-cooled condenser is used in this embodiment, when a water-cooled condenser is used, the same effect can be obtained by using a condenser inlet cooling water temperature detection device instead of the cooling air temperature detection device.

〔Effect of the invention〕

Since the present invention is configured as described above, even if the pressure on the high pressure side of the refrigeration cycle drops under conditions such as winter when the temperature of the heat medium (air, water, etc.) that cools the condenser is low, the low pressure side The pressure may correspond to an evaporation temperature at which the evaporator does not freeze.

[Brief explanation of drawings]

FIG. 1 is a system diagram of a refrigeration cycle according to an embodiment of the present invention. 1...Compressor, 2,6,8,13.15...Piping,
3...Air-cooled condenser, 4,5...Condenser blower device,
7... Throttle device, 9... Evaporator, 10... Heat transfer tube, 11... Water inlet, 12... Water outlet, 14... Solenoid valve, 16... Low pressure side pressure detection Device, 17... High pressure side pressure detection device, 18... Cooling air temperature detection device.

Claims (1)

[Claims] 1. The low-pressure side pressure detection device of the refrigeration cycle and a portion of the discharge gas of the compressor are directly routed by bypassing the condenser and expansion device.
A bypass pipe is provided with a solenoid valve leading to the evaporator, and when the low pressure side pressure becomes less than the set value of the low pressure side pressure detection device, the solenoid valve is opened and a part of the gas discharged from the compressor is A refrigeration system characterized in that the refrigeration system is made to flow directly into the evaporator.