JPH03122474A - Freezing device - Google Patents

Abstract

PURPOSE:To improve a defrosting effect and to shorten a defrosting time by a method wherein through control of a flow rate control means during defrosting of a second heat exchanger, an amount of cooling water fed to a first heat exchanger is minimized. CONSTITUTION:When a defrosting starting signal is inputted to a defrost starting signal input part 18 from the outside, for example, a timer, a central control part 19 transmits a control signal stored in a memory part 20 and responding to the given minimum number of revolutions of a motor, with the aid of which a cooling water pump 12 is run, to an inverter 22. The inverter 22 receives a control signal to decrease the number of revolutions of a motor to a given minimum value, and an amount of cooling water passing through a cooling water pump 12 and fed to a condenser 3 is reduced to a minimum. This operation reduces an amount of heat exchange effected in a condenser 3 and increases a condensing pressure in the condenser 3, resulting in the increase of the flow rate of hot gas flowing through a bypass circuit 10. As a result, the defrosting efficiency of an air cooler 6 is improved and a defrosting time can be shortened.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a refrigeration system in which nitrogen removal from a heat exchanger such as an air cooler is performed using hot gas obtained from a compressor. .

[Conventional technology]

FIG. 3 is a configuration diagram showing a conventional refrigeration system, in which 1 is a compressor that pressurizes refrigerant to form hot gas, 1a is an intercooler provided upstream of the compressor 1, and 2 is a compressor 1. 3 is a check valve that prevents backflow of the hot gas output from the check valve 2; 3 is a condenser serving as a first heat exchanger that condenses the hot gas that has passed through the check valve 2 with cooling water to form a refrigerant liquid; The above-mentioned refrigerant liquid passes through a production solenoid valve, 5 passes through the production solenoid valve 4 and depressurizes the required refrigerant liquid, an expansion valve 6, air cooling as a second heat exchanger that vaporizes the depressurized refrigerant liquid. container, T is air cooler 6
8 is an intercooler solenoid valve through which a part of the refrigerant liquid obtained from the condenser 3 passes, and 9 is an intercooler solenoid valve. The refrigerant liquid that has passed through the valve 8 is depressurized and transferred to the intercooler 1a.
10 is a bypass circuit for directly supplying the hot gas to the air cooler 6 during defrosting of the air cooler 6; 11 is a hot gas expansion valve provided on the inlet side of the bypass circuit 10; This is a solenoid valve for gas.

12 is a cooling water pump for feeding cooling water to the condenser 3; 13 is a cooling water valve provided on the inlet side of the condenser 3;
14 is a cooling water outlet valve provided on the outlet side of the condenser 3;
5 is a cooling tower that cools the cooling water from the cooling water outlet valve 14; 16 is a fan for the cooling tower; and 17 is a temperature sensor that detects the temperature of the cooling water cooled by the cooling tower 15.

Next, the operation will be explained.

First, in the refrigeration cycle, the refrigerant that is pressurized by the compressor 1 and turned into hot gas passes through the check valve 2'jfr, is liquefied in the condenser 3, passes through the solenoid valve 4, and then is depressurized by the expansion valve 5. and is evaporated in the air cooler 6. The liquid content of the vaporized refrigerant is removed by an Akiemulator T, and then
It is sucked into the compressor 1 again. In addition, a part of the refrigerant liquid that has exited the condenser 3 passes through an intercooler solenoid valve 8, is depressurized by an intercooler expansion valve 9, and is supplied to the intercooler 1a, thereby generating hot gas. It's cooling down. If refrigeration operation is continued in this refrigeration cycle, frost buildup on the heat transfer surface of the air cooler 6 will progress, so the frost must be removed periodically.

In the defrost cycle, the production solenoid valve 4 is closed and the expansion valve 5 is closed.
At the same time, the hot gas electromagnetic valve 11 is opened and the hot gas from the compressor 1 is transferred to the bypass circuit 10.
By being directly supplied to the air cooler 6 through
The air cooler 6 is defrosted.

At this time, the amount of refrigerant gas (hot gas amount) flowing through the bypass circuit 10 depends on the condensing pressure in the condenser 3. If the condensing pressure is high, the amount of refrigerant gas flowing directly to the air cooler 6 increases, and the condensing pressure increases. If it is low, the amount of refrigerant flowing into the condenser 3 will be large, and the amount of refrigerant gas flowing directly to the air cooler 6 will be small. When the amount of refrigerant gas to the air cooler 6 decreases, defrosting of the air cooler 6 will take a long time.

On the other hand, since the condensation pressure of the refrigerant is a function of the condensation temperature, in order to increase the condensation pressure in the condenser 3, it is necessary to increase the condensation temperature, that is, the cooling water temperature.

Therefore, in order to maintain the pressure above a predetermined condensing pressure, the temperature sensor 17 that detects the temperature of the cooling water stops the cooling tower fan 16 when the temperature of the cooling water is low to raise the temperature of the cooling water. In addition, 71 in 1 for cooling tower
If the cooling water temperature is still low even after stopping the cooling water, manually tighten the cooling water population valve 13 and the cooling water outlet valve 14 to reduce the amount of cooling water to maintain the condensation pressure in the condenser 3. methods are being used.

[Problem to be solved by the invention]

Since the conventional refrigeration system is configured as described above, there is a limit to the cooling water temperature control range υ if the cooling water inlet temperature is controlled only by starting and stopping the cooling tower 7-amp 16.
For this reason, the amount of cooling water must be adjusted by manually operating the cooling water population valve 13 or the cooling water outlet valve 14, which poses problems such as the hassle of manually opening and closing the valves.

This invention was made to solve the above-mentioned problems, and provides a refrigeration device that can improve the defrosting effect during defrosting of the heat transfer surface of an air cooler and shorten the defrosting time. b with the purpose of obtaining.

[Means to solve the problem]

The refrigeration system according to the present invention includes a flow rate control means for feeding cooling water to a first heat exchanger such as an air cooler, and a flow rate control means for supplying cooling water to a first heat exchanger such as an air cooler, and a flow rate control means for supplying cooling water to a predetermined minimum flow rate in response to a defrosting start signal. and a control device that generates a control signal for operating the flow rate control means.

[Effect]

In this invention, when a defrosting start signal is input at the time of starting defrosting, the control device takes out a control signal corresponding to a predetermined minimum flow rate stored in advance, and based on this control signal, the flow rate control means The condensing pressure of the first heat exchanger is increased by controlling the amount of cooling water to a predetermined minimum flow rate.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, the same parts as in FIG. 3 are given the same reference numerals, and their explanation will be omitted.

In FIG. 1, 18 is a defrost start signal input unit that receives a defrost start signal from the outside, 19 is a central control unit consisting of a CPU, etc., to which the defrost start signal is input, and 20 is a control unit that controls the minimum flow rate of cooling water. A storage section 21 stores a control signal to be set, a defrosting start signal input section 18, a central control section 19, and a storage section 2o.
It is a control device consisting of.

22 is an inverter that controls the rotation speed of the drive motor of the cooling water pump 12 based on a control signal output from the control device 21; 23 is a central control unit 19 that detects the pressure of hot gas output from the compressor 1; This is a pressure sensor that sends data to the

In this embodiment, the cooling water pump 12 serves as a flow rate control means.

Next, the operation will be explained.

When a defrost start signal is input from an external device such as a timer (not shown) to the defrost start signal input section 18, the central control section 1
9 transmits to the inverter 22 a control signal corresponding to a predetermined minimum rotational speed of the motor that drives the cooling water pump 12, which is stored in the storage unit 2o.

Upon receiving this control signal, the inverter 22 sets the rotational speed of the motor to a predetermined minimum rotational speed, thereby minimizing the amount of cooling water fed to the condenser 3 passing through the cooling water pump 12. Due to this operation, the amount of heat exchanged in the condenser 3 is reduced υ, and the condensation pressure in the condenser 3 is increased, thereby increasing the flow rate of hot gas flowing in the bypass circuit 1o.

If the condensation pressure in the condenser 3 becomes higher than a predetermined pressure, it is not favorable for other equipment such as the compressor 1. Therefore, if the temperature detected by the pressure sensor 23 exceeds a predetermined value, the pressure sensor 23 sends a signal to the central control unit 19.

When the central control unit 19 receives the above signal, the central control unit 19 controls the inverter 2.
A signal for increasing the rotational speed of the cooling water pump 12 is output to 2.

When the signal from the pressure sensor 23 to the central control unit 19 disappears, the control signal stored in the storage unit 20 is sent to the inverter 22 again, and the motor of the cooling water pump 12 is reduced to a predetermined minimum rotational speed to start operation. continue.

In this way, by controlling the rotation speed of the cooling water pump 12 during the defrosting period, the condensation pressure in the condenser 3 can always be maintained at a predetermined pressure or higher.

In the above embodiment, the amount of cooling water is controlled by controlling the rotation speed of the drive motor of the cooling water pump 12.
As shown in FIG. 2, a control signal from the control device 21 is sent to the inlet valve control device 24, and in response, the large opening valve control device 24 controls the opening degree of the cooling water valve 13 to a predetermined minimum flow rate. It may be set at once.

〔Effect of the invention〕

As described above, according to the present invention, when defrosting the second heat exchanger, the flow rate control means such as the cooling water pump and the cooling water population valve are controlled to supply the amount of cooling water to the first heat exchanger. Since the configuration is configured so that K Therefore, the effect of increasing the defrosting effect and shortening the defrosting time can be obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a refrigeration system according to an embodiment of the present invention, FIG. 2 is a block diagram showing a refrigeration system according to another embodiment of the invention, and FIG. 3 is a block diagram showing a conventional refrigeration system. be. 1 is a compressor, 3 is a condenser, 5 is an expansion valve, 6 is an air cooler, 10 is a bypass circuit, 12 is a cooling water pump, 13 is a cooling water valve, and 21 is a control device. In addition, the same symbols in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] A compressor that compresses refrigerant into hot gas, a first heat exchanger that condenses the hot gas with cooling water, and a flow rate control provided in a flow path that supplies the cooling water to the first heat exchanger. means, an expansion valve for reducing the pressure of the refrigerant liquid condensed in the first heat exchanger, a second heat exchanger for vaporizing the reduced pressure refrigerant liquid and returning it to the compressor; a bypass circuit that directly supplies the hot gas to the second heat exchanger during defrosting of the heat exchanger; and a bypass circuit that supplies the hot gas directly to the second heat exchanger when defrosting the heat exchanger; A refrigeration system comprising a control device that controls a control means.