JPH109726A - Defrosting method and apparatus for freezer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce heat of hot gas consumed in heating of a liquid refrigerant, and shorten the time of defrosting operation by performing operation changeover to defrosting operation after preheating operation for raising refrigerant condensation temperature is performed for a predetermined time before starting of the defrosting operation when fresh air temperature is a set value or lower. SOLUTION: When a command from a timer 21 is inputted into preheating control means 22 after a predetermined time from predetermined defrosting starting time, the preheating control means 22 compares set temperature inputted from a temperature set means 23 with fresh air temperature inputted from a fresh air temperature sensor 18, and if the former is lower than the latter, execution of the preheating operation is determined. Herein, if a freezer is interrupted, it is started, and simultaneously a command is outputted to condensation fans 6A, 6B to reduce the rotational speeds and the number of machines. The preheating operation is performed for a predetermined time prior to the defrosting operation and then refrigerant condensation temperature is raised so that temperature of a liquid refrigerant is also raised. Thus, there is reduced heat of hot gas consumed in heating of the liquid refrigerant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner,
The present invention relates to a method and apparatus for defrosting a refrigerating device such as a refrigerator.

[0002]

2. Description of the Related Art A refrigerant circuit of a conventional refrigeration system is shown in FIG. During the cooling operation of the refrigerating apparatus, the refrigerant discharged from the compressor 1 enters the condenser 3 through the three-way valve 2 as shown by a solid line arrow, where it is blown by a plurality of condenser fans 6A and 6B. Condensed and liquefied by radiating heat to the outside air.

The liquid refrigerant passes through a receiver 4, a check valve 5, and an electromagnetic opening / closing valve 7, and enters a throttle mechanism 8 composed of an expansion valve and the like, and is adiabatically expanded by being throttled here. This refrigerant enters the evaporator 9, where it is evaporated and vaporized by cooling the inside air blown by the evaporator fan 15, and then returns to the compressor 1 via the accumulator 10.

[0004] A defrosting operation is performed at predetermined intervals. During this defrosting operation, the hot gas bypass discharged from the compressor 1 causes the three-way valve 2, the hot gas circuit 11, the liquid refrigerant pipe 16, the bypass circuit 12, and the electromagnetic It enters the evaporator 9 through the bypass valve 13,
Here, the temperature is lowered by melting the frost attached to the surface, and then returns to the compressor 1 via the accumulator 10. During this defrosting operation, the condenser fans 6A and 6B and the evaporator fan 15 are stopped, the three-way valve 2 is switched in the direction of the dashed arrow, and the electromagnetic on-off valve 7 is closed.

[0005]

In the above-mentioned conventional refrigeration apparatus, during the defrosting operation, the hot gas flowing out of the hot gas circuit 11 accompanies the evaporator 9 with the liquid refrigerant remaining in the liquid refrigerant pipe 16. Flows into. Therefore, when the outside air temperature is low, the temperature of the liquid refrigerant is also low, and a large amount of heat of the hot gas is consumed to heat the liquid refrigerant, so that the time required for defrosting becomes long. Might be output.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the gist of the first invention is to provide a compressor, a condenser, a throttle mechanism, an evaporator, and the like. A refrigeration system comprising a refrigerant circuit comprising: a hot gas discharged from the compressor and introduced into the evaporator through a hot gas bypass to defrost the defrosting operation when the outside air temperature is equal to or lower than a set value. A defrosting method for a refrigerating apparatus, comprising performing a preheating operation for increasing a refrigerant condensing temperature for a predetermined time before starting, and then switching to a defrosting operation to perform defrosting.

The gist of the second invention is to provide a refrigerant circuit including a compressor, a condenser, a throttle mechanism, an evaporator, etc., and to transfer hot gas discharged from the compressor through a hot gas bypass. In the refrigeration system for introducing and defrosting the evaporator, an external air temperature sensor for detecting the external air temperature is provided, and when the external air temperature detected by the external air temperature sensor is equal to or less than a set value, a predetermined time before the start of the defrosting operation. A defrosting device for a refrigerating device, wherein a preheating control means for performing a preheating operation for increasing a refrigerant condensing temperature is added to the defrosting control device.

The preheating control means may be constituted by means for reducing the number of rotations or the number of operating fans of the condenser fan.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention is shown in FIGS. As shown in FIG. 3, an outside air temperature sensor 18 for detecting the temperature of the outside air sent to the condenser 3 is provided, and the detected temperature of the outside air temperature sensor 18 is input to the defrost control device 20. I have. A control flowchart of the defrost control device 20 is shown in FIG.
Is shown in

During the cooling operation, the three-way valve 2 is turned off by a command from the defrost control device 20, and the compressor 1, the fan 6A for the condenser,
6B, the evaporator fan 15 is turned ON, the solenoid on-off valve 7 is opened,
Since the electromagnetic bypass valve 13 is closed, the refrigerant circulates as shown by the solid arrow in FIG.

A predetermined time from a predetermined defrost start time,
For example, when a command from the timer 21 is input to the preheating control means 22 30 minutes before, the preheating control means 22
By comparing the outside air temperature input from 18 with the set temperature input from the temperature setting means 23, for example, -10 ° C., if the former is lower than the latter, it is determined that the preheating operation is to be performed. If it is in the middle, this is started up and output to the condenser fans 6A, 6B at the same time to reduce the number of rotations or the number of operating units. As a result, the flow rate of the outside air flowing through the condenser 3 is reduced, and the condensing ability of the condenser 3 is reduced, so that the refrigerant condensing temperature increases.

When the timer 21 times out, that is, when the defrost start time is reached after a certain period of time, the defrost control device
The compressor 1 and the three-way valve 2 are turned ON, the condenser fans 6A and 6B and the evaporator fan are turned OFF, the electromagnetic on-off valve 7 is closed, and the electromagnetic bypass valve 13 is opened by a command from 20, so that the refrigerant is as shown in FIG. Circulate as shown by the dashed arrow.

Since the refrigerant condensing temperature is increased by performing the preheating operation for a predetermined time prior to the defrosting operation, the temperature of the liquid refrigerant in the liquid refrigerant pipe 16 at the start of the defrosting operation is also high. Therefore, at the beginning of the defrosting operation, the high-temperature liquid refrigerant enters the evaporator 9 with the hot gas, so that the heat of the hot gas consumed for heating the liquid refrigerant is reduced, and thus the defrosting operation time is shortened. can do.

In the above embodiment, the defrosting operation is performed at regular intervals, but when the amount of frost adhering to the evaporator 9 reaches a predetermined amount, the preheating operation is performed according to a command from the evaporator temperature sensor that detects this. Can also be performed. Also,
During the preheating operation, the rotation speed of the compressor 1 can be increased to increase the refrigerant condensation temperature.

[0015]

According to the present invention, when the outside air temperature is equal to or lower than the set value, a preheating operation for increasing the refrigerant condensing temperature is performed for a predetermined time before the defrosting operation is started, and then the operation is switched to the defrosting operation for defrosting. Since the heat of the hot gas consumed for heating the liquid refrigerant at the beginning of the defrosting operation can be reduced, the defrosting operation time can be shortened.

If the number of rotations or the number of operating fans of the condenser fan is reduced by the preheating control means, the refrigerant condensing temperature can be easily raised.

[Brief description of the drawings]

FIG. 1 is a control flowchart showing an embodiment of the present invention.

FIG. 2 is a control block diagram of the embodiment.

FIG. 3 is a system diagram of the embodiment.

FIG. 4 is a refrigerant circuit diagram of a conventional refrigeration apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 2 Three-way valve 3 Condenser 4 Receiver 5 Check valve 6A, 6B Fan for condenser 7 Electromagnetic on / off valve 8 Throttle mechanism 9 Evaporator 10 Accumulator 15 Fan for evaporator 11, 12 Hot gas bypass 13 Electromagnetic bypass valve 18 Outside Temperature sensor 20 Defrost control device

Claims (3)

[Claims] 1. A defrosting apparatus comprising a refrigerant circuit comprising a compressor, a condenser, a throttle mechanism, an evaporator, etc., and introducing hot gas discharged from the compressor to the evaporator via a hot gas bypass. In the refrigeration apparatus, when the outside air temperature is equal to or lower than a set value, a preheating operation for increasing the refrigerant condensing temperature is performed for a predetermined time before the start of the defrosting operation, and then the defrosting operation is switched to the defrosting operation. How to defrost the device. 2. A defrosting device comprising a refrigerant circuit comprising a compressor, a condenser, a throttle mechanism, an evaporator and the like, and introducing hot gas discharged from the compressor to the evaporator via a hot gas bypass. In the refrigeration apparatus, when an outside air temperature sensor for detecting an outside air temperature is provided and the outside air temperature detected by the outside air temperature sensor is equal to or less than a set value, a preheating operation in which the refrigerant condensing temperature is increased for a certain time before the defrosting operation is started. A defrosting device for a refrigerating device, wherein preheating control means for performing the operation is provided in the defrosting control device. 3. The defrosting device for a refrigeration system according to claim 2, wherein said preheating control means reduces the number of rotations or the number of operating fans of said condenser fan.