KR20120139022A - Defrost operation method of the heat pump - Google Patents

Abstract

PURPOSE: A defrost operation method for a heat pump system using a binary refrigerating cycle is provided to rapidly defrost refrigerant by bypassing the refrigerant to a low temperature compressor using a bypass valve in case the refrigerant is not expanded enough. CONSTITUTION: A defrost operation method for a heat pump system using a binary refrigerating cycle comprises following steps. Whether or not the temperature of air is below negative tem degrees is determined for starting defrost operation when cooling operation stops. Whether or not the pressure of refrigerant is below 3.5 kg/cm^2 is determined. The refrigerant is expanded in an expansion valve(5a) while an electric valve(B2) is opened if the temperature of the air is above negative tem degrees and the pressure of the refrigerant is above 3.5kg/cm^2. The refrigerant is compressed at high temperature in a low temperature compressor(1) after evaporating the refrigerant in a heat exchanger(4) when the refrigerant is expanded. The refrigerant compressed at high temperature circulates in an air heat exchanger(6), and defrosted. The defrosting time is set as ten minute, and the defrost operation stops after the ten minutes. [Reference numerals] (AA) Heating operation; (BB) Cooling operation/defrosting operation

Description

[0001] The present invention relates to a defrost operation method of the heat pump,

The present invention relates to a defrosting operation method of a heat pump apparatus using a two-way refrigeration cycle, and more particularly, to a defrosting operation method of a heat pump apparatus using a two- The refrigerant is directly compressed in the low temperature compressor without expanding the refrigerant at the expansion side under the condition that the temperature is not more than -10 ° C or the refrigerant pressure is not more than 3.5 kg / cm 2, whereby the time for lifting the refrigerant to a high temperature is shortened as much as possible, And more particularly, to a defrost operation method of a heat pump apparatus using a two-way refrigeration cycle.

Generally, the two-cycle refrigeration cycle is divided into a low-temperature side using a low-temperature refrigerant boiling at -52 ° C or lower and a high-temperature side using a high-temperature refrigerant boiling at -11 ° C or above relatively smoothly. If the condensation occurs in one cascade heat exchanger, the temperature of the refrigerant discharge gas on the high temperature side can be maintained at a constant high temperature of 100 ° C or more even when the outdoor temperature is low in winter, which is effective for hot water production.

Conventional patent No. 859311 is a heat pump which is composed of two low-temperature side and high-temperature side for cooling and heating and hot water supply. In the conventional heat pump apparatus, in the simultaneous production mode of cold and hot water, the high temperature side condenser produces hot water by heat exchange with water of the hot water tank. And the refrigerant passing through the high temperature side condenser passes through the auxiliary heat exchanger to lower the expansion temperature.

However, since the refrigerant on the low-temperature side is heat-exchanged with the water in the cold-water tank in the low-temperature side evaporator, the cold water is recovered by the low-temperature compressor without passing through the low-temperature evaporator / condenser There is a disadvantage in that the low-temperature side cycle is unstable due to the lack of refrigerant and the efficiency is lowered.

Since the conventional outdoor air heat exchanger forms a refrigerating cycle without using it in the cooling / heating simultaneous mode because it functions as a condenser in the cooling or defrost mode, the circulating pipe of the low temperature refrigerant is piped in the outside air heat exchanger, If the refrigerant is not recovered by the compressor, it is natural that the refrigerant circulation amount in the entire low-temperature-side refrigeration cycle becomes insufficient, so that the cycle becomes unstable and overcompression or overheating occurs. In severe cases, the refrigerant circulation pipe is damaged due to welding, There were technical drawbacks.

The applicant of the present invention has filed a pending application of the heat pump apparatus with the above-mentioned prior art in view of the above-mentioned Patent Application Publication No. 2010-0130137. This is because when the compressor capacity on the low temperature side and the high temperature side are set to be equal to 1: 1 and the low temperature side compressor is set to a high temperature in the coldest period of -15 ° C or lower in the winter season, the evaporation amount of the low temperature side refrigerant is not sufficient, The heat exchange with the high temperature side is smoothly carried out by the heat discharge, and there is no trouble in the production of the hot water. Also, when the low temperature side compressor is set to be lower than 50% Is low and the compressor is not overloaded and the problem of compressor breakage is solved.

However, since the refrigerant discharge line of the cooling and defrost heat exchanger is recovered to the low-temperature side compressor through the cascade heat exchanger during the cooling and defrosting operations, the circulation of the refrigerant is not performed quickly. In addition, regardless of changes in outside air temperature during defrosting operation, the defrosted refrigerant in the air heat exchanger is expanded and sent to the low-temperature side compressor. When the refrigerant pressure is lowered below -10 ° C, the refrigerant does not expand. The defrosting time is increased.

SUMMARY OF THE INVENTION The present invention has been made in view of the conventional problems, and it is an object of the present invention to provide a refrigeration cycle of a low temperature side and a high temperature side so as to enable simultaneous operation of cooling, heating, defrosting, Or when the pressure of the refrigerant is 3.5 kg / cm 2 or less, the refrigerant is directly compressed in the low-temperature compressor without expanding the refrigerant at the expansion side so that the time for lifting the refrigerant to the high temperature is shortened as much as possible, And a defrosting operation method of the heat pump device used.

In order to achieve the above object, the present invention provides a cascade heat exchanger comprising: a low temperature side refrigeration cycle and a high temperature side refrigeration cycle, wherein condensation of the low temperature side low temperature refrigerant and evaporation of the high temperature side high temperature refrigerant are performed in one cascade heat exchanger, Temperature refrigerant discharged from the low-temperature side refrigerant compressor when the malfunction occurs in the air heat exchanger installed in the low-temperature side compressor, the defrosting operation method of the heat pump apparatus using the dual- A step of stopping the heating operation when the temperature is lower than or equal to 15 ° C or when the cumulative heating operation time is more than one hour, and when the heating operation is stopped, when the outside air temperature is -10 캜 or less, determining whether the refrigerant pressure is 3.5 kg / cm 2 or less, Opening the solenoid valve 2 on the low-temperature side so that the refrigerant expands at the low-temperature expansion side 2 when the outside air temperature is -10 ° C or higher and the refrigerant pressure is 3.5 kg / cm 2 or more in the step A step of evaporating the refrigerant in the heat exchanger for cooling and defrosting the refrigerant and compressing the refrigerant to a high temperature in the low temperature compressor, a step of defrosting the refrigerant compressed in high temperature by circulating the refrigerant to the air heat exchanger, And a defrosting operation is terminated when 10 minutes have elapsed.

The present invention is a cycle capable of cooling, heating, defrosting, and cooling / heating simultaneously. When defrosting of the winter air heat exchanger is required, rapid defrosting is possible because the high temperature refrigerant discharged from the low temperature compressor is directly sent to the air heat exchanger.

Since the refrigerant discharged from the low-temperature compressor during the defrosting operation is circulated to the inside of the outside air heat exchanger, the defrosting of the heat exchanging fins and the refrigerant pipe can be quickly performed. In the defrosting process, the refrigerant expands normally through the low-temperature expansion valve, and is circulated to the low-temperature compressor after evaporating in the heat exchanger for cooling and defrosting. However, since the refrigerant can not be sufficiently expanded at the low temperature expansion under the condition that the outdoor temperature is lower than -10 DEG C or the pressure of the refrigerant falls to 3.5 kg / cm < 2 >, the bypass valve is used to cool the refrigerant at the low temperature expansion side The compressor is bypassed by the low-temperature compressor without being inflated, so that the refrigerant discharge temperature of the compressor is not lowered and the defrosting is performed quickly.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a block diagram of a dual-refrigerating cycle heat pump apparatus according to an embodiment of the present invention; Fig.
FIG. 2 is a flowchart of defrosting operation of the two-way refrigeration cycle heat pump apparatus according to the embodiment of the present invention.

FIG. 1 is a block diagram of a dual-refrigerating cycle heat pump apparatus. The low-temperature side refrigeration cycle includes a low-temperature compressor 1 for compressing refrigerant at a high temperature and a high pressure during heating in winter, a cascade heat exchanger A), a cold expansion valve 1 (5) for expanding the refrigerant gas condensed in the heat radiation process, and an air heat exchanger (6) for evaporating the refrigerant that has become liquid in the expansion process to air heat. At this time, the electromagnetic valve 2 (B2) is closed and the solenoid valve 1 (B1) is opened so that the low temperature refrigerant is directed to the low temperature expansion side 1 (5).

In order to cool the axial cold storage tank 7 with the low temperature side refrigeration cycle, the refrigerant discharged from the low temperature compressor 1 is directed to the air heat exchanger 6 without going to the cascade heat exchanger A Way valve 3 is provided. The refrigerant discharged from the air heat exchanger 6 is circulated to the cooling and defrosting heat exchanger 4 connected to the axial cold storage 7 through the low temperature expansion side 2 5a and discharged to the discharge pipe 8, The discharge pipe 8 is directly connected to the refrigerant recovery line L1 via the connecting portion 9 and is circulated to the low temperature compressor 1. [ At this time, the solenoid valve 1 (B1) is closed and the solenoid valve 2 (B2) is opened so that the low temperature refrigerant is directed to the low temperature expansion side 2 (5a).

Hot gas refrigerant discharged from the low-temperature compressor (1) by the four-way valve (3) during the defrosting operation required for defrosting the air heat exchanger (6) provided outside the low temperature side in winter is supplied to the air heat exchanger 6) immediately to defrost the malaise. Then, the electromagnetic valve 1 (B1) is closed and the solenoid valve 2 (B2) is opened to expand the refrigerant to the low temperature expansion side 2 (5a) and sent to the cooling and defrosting heat exchanger (4) . The amount of heat required for evaporation is the hot water of a storage tank 13 which will be described later. When the hot water of the storage tank 13 is circulated to the cooling and defrosting heat exchanger 4, the refrigerant is evaporated and circulated to the low temperature compressor 1 A defrost cycle is formed.

During the defrosting operation, the pressure of the refrigerant changes depending on the outside temperature, which is 3.0 kg / cm 2 at -10 ° C and 2.5 kg / cm 2 at -20 ° C. Therefore, according to the present invention, when the refrigerant pressure falls below 3.5 kg / cm 2, that is, when the outside air becomes colder than -10 ° C, the refrigerant does not expand at the low-temperature expansion side 2 (5a), passes through the cooling and use heat exchanger The bypass valve B3 is provided to be sent to the low-temperature compressor 1. [ Therefore, the temperature of the refrigerant discharged from the low-temperature compressor (1) rises rapidly during the defrosting operation in the cold season, so that the defrosting time can be shortened.

The high-temperature-side refrigeration cycle includes a high-temperature compressor (10) for compressing refrigerant at a high temperature and a high pressure, a heat storage heat exchanger (11) for radiating the heat of the compressed refrigerant to the heat storage tank (13) (12) and the refrigerant which has become liquid in the expansion process is evaporated in the cascade heat exchanger (A) by the heat of the low temperature side low temperature refrigerant and circulated again to the high temperature compressor (10).

The refrigerant discharged from the low-temperature compressor (1) on the low-temperature side at the time of simultaneous cooling and heating operation is circulated to the cascade heat exchanger (A) via the four-way valve (3) and used as a heat source for evaporating the refrigerant on the high- Therefore, on the high-temperature side, the high-temperature refrigerant is discharged to the heat storage heat exchanger (11) by the operation of the high-temperature compressor (10), and the water in the heat storage tank (13) is made hot so that heating and hot water production become possible. The refrigerant that has passed through the cascade heat exchanger A from the low temperature side is expanded toward the low temperature expansion side 2 (5a) due to the opening of the solenoid valve 2 (B2) and then circulated to the heat exchanger 4 for cooling and defrosting. At this time, the water of the axial cold tank 7 is cooled and used as a cooling heat source.

FIG. 2 is a flow chart showing the defrosting operation method of the embodiment of the present invention in a stepwise manner. In the winter heating operation step S1, external air heat exchanger 6 causes malaise on the surface, which interferes with air heat exchange. Therefore, it is necessary to periodically perform the defrosting. It is necessary to perform the defrosting periodically. If the defrosting operation is performed at a temperature lower than 15 ° C, (S4) for stopping the heating operation when the image is less than or equal to 15 DEG C or when the operation accumulation time exceeds one hour (S4). When the heating operation is stopped, the defrosting operation The defrosting operation proceeds to step S5 in which it is determined whether the outside air temperature is equal to or lower than -10 占 폚, and step S6 in which it is determined whether the refrigerant pressure is equal to or lower than 3.5 kg / cm2.

(S7) of opening the solenoid valve 2 (B2) to expand the refrigerant at the low-temperature expansion side 2 (5a) when the outdoor temperature is higher than -10 ° C and the refrigerant pressure is 3.5 kg / (S8) of compressing the refrigerant to a high temperature in the low-temperature compressor (1) after evaporating the refrigerant in the cooling and heating heat exchanger (4) when the refrigerant is inflated in the step (S9) of causing the defrosting to be performed while circulating to the heat exchanger (6), and a step (S10) of setting the defrosting operation time and ending the defrosting operation when 10 minutes have elapsed.

If the outside air temperature is lower than -10 ° C or the refrigerant pressure is 3.5 kg / cm 2 or less, the bypass valve B3 is opened so as not to pass through the step S7, and the process proceeds to the step S8 Is added. Due to this process, when the refrigerant is cold or the refrigerant is at a low pressure, the refrigerant is directly compressed in the compressor without being inflated, so that the temperature of the refrigerant is rapidly increased and the defrosting time can be shortened. Reference numerals 1a and 1b denote low-temperature oil separators and liquid separators, 10a denotes a high-temperature liquid separator, and 2 denotes a low-temperature side pressure gauge.

The present invention thus constituted has the following operating characteristics.

When the low-temperature compressor 1 starts operating in the winter, the low-temperature refrigerant is compressed to about 15.5 Kg / cm 2 and is discharged to about 50 ° C., and is discharged to the cascade heat exchanger A through the oil separator 1a and the four- The refrigerant is evaporated in the air heat exchanger 6 and sucked into the low temperature compressor 1 to form a low temperature cycle.

When the outdoor air temperature in winter is colder than -15 ℃, the refrigerant passing through the cold expansion 1 (5) is discharged at -22 ℃ to maintain the evaporation temperature difference of 7 ℃ with outside air. It is a low temperature refrigerant that evaporates at -56 ℃ The air heat exchanger (6) sufficiently absorbs ambient air heat and the refrigerant is completely evaporated. The low-temperature compressor (1) sufficiently compresses the evaporated refrigerant and then sends it to the cascade heat exchanger (A), so that it can sufficiently absorb heat in the high temperature side refrigeration cycle to raise the temperature of the heat storage tank (13).

In the cascade heat exchanger (A) in the high temperature side refrigeration cycle in winter, the refrigerant having passed through the high temperature expansion valve (12) evaporates at about 5 ° C .; the evaporation temperature is very importantly controlled. Temperature compressor (10) and the 12? The refrigerant is compressed at a rate of 13 kg / cm 2 and is heat-exchanged with the hot water of the heat storage tank 13 in the heat storage heat exchanger 11 and condensed. When the refrigerant expands through the high temperature expansion 12 as a throttling device via the receiver and the filter drier, A continuous cycle is formed in which the refrigerant is sucked back to the high-temperature compressor 10 through the evaporation process.

Considering that the temperature at the lower end of the storage tank 13 is about 5 ° C lower than the upper end, the hot water, which is a production purpose, is operated by the hot water pump 13a installed at the lower end, Heat-exchanged, and the temperature rises to about delta t of about 5 ° C, and is then returned to the heat storage tank (13), where it is stored in a high temperature heat of 70 ° C or higher and hot water.

Defrosting occurs in the air heat exchanger (6) during the heating operation in the winter, which interferes with air heat exchange. At this time, defrosting operation as shown in Fig. 2 proceeds. The refrigerant discharged from the low-temperature compressor 1 at a temperature of about 80 DEG C during the defrosting operation is directly sent to the air heat exchanger 6 via the four-way valve 3, so that the malaise is quickly removed. The refrigerant discharged after defrosting in the air heat exchanger 6 is expanded while being circulated to the low temperature expansion side 2 (5a) by the opening of the solenoid valve 2 (B2) and is then expanded in the heat exchanger 4 for cooling and defrosting, The refrigerant is circulated to the low temperature compressor 1 by being directly connected to the low temperature side refrigerant recovery line L1 via the discharge pipe 8 and the connecting portion 9,

At this time, the bypass valve B3 is opened so that the refrigerant is not circulated to the low-temperature expansion side 2 (5a) and the low-temperature compressor (1 . In cold weather, since the pressure of the refrigerant is low, sufficient evaporation is not performed at the low temperature expansion side 2 (5a), so that the refrigerant discharge temperature of the low temperature compressor (1) can not be raised quickly. In consideration of the outside temperature and the pressure condition of the refrigerant, the present invention controls the operation so that the refrigerant is directly compressed in the low-temperature compressor (1) without being inflated in the low-temperature expansion side (5a) Since defrosting can be performed quickly, the heating efficiency is improved.

In the spring and fall season, since the outside temperature is 10 ° C, the refrigerant discharged from the low-temperature expansion valve 1 (5) is expanded to 7.3 ° C in order to maintain the evaporation temperature of 2.7 ° C to reduce the evaporation load and the compression load of the low- . Especially, in the season of change, the cooling and heating occur frequently at the same time.

First, the refrigerant discharged from the low temperature side low temperature compressor (1) is circulated to the cascade heat exchanger (A) via the four - way valve (3) and used as a heat source for evaporation of the high temperature side refrigerant. Therefore, at the high temperature side, the water in the heat storage tank 13, in which the refrigerant discharged from the high-temperature side compressor 10 is circulated to the heat storage heat exchanger 11, is heated to a high temperature to make it a hot water and a heating heat source. The refrigerant discharged from the heat storage tank 13 is expanded through the high temperature expansion 12 and then evaporated in the cascade heat exchanger A to be circulated to the high temperature compressor 10, The refrigerant on the low temperature side discharged from the compressor 2 is expanded while passing through the low temperature expansion side 2 (5a) due to the closing of the solenoid valve B1 and the opening of the solenoid valve B2 and is evaporated in the heat exchanger 4 for cooling and defrosting Cooling the water in the cold storage tank (7) to a low temperature to make a cooling heat source.

In the cooling operation in the summer, the hot water consumption is reduced, so that the hot side refrigeration cycle intermittently operates or stops the operation so that hot water of the storage tank 13 is maintained, while the low temperature side refrigeration cycle is switched to cooling and actively operates. When the low-temperature compressor (1) is operated in summer, the compressed refrigerant is sent from the four-way valve (3) to the air heat exchanger (6) and condensed to the outside air heat. The refrigerant of middle temperature and high pressure is condensed to about 20 ° C, (5a) and undergoes an expansion process. The cooling cycle in which the recovery pipe 8 is connected to the low temperature side refrigerant recovery line L1 through the connection portion 9 and circulated to the low temperature compressor 1 after being sent to the cooling and distillation heat exchanger 4 . At this time, the water in the axial cold storage tank 7 is circulated through the cold water pump 7a to the cooling and defrosting heat exchanger 4, and is cooled to be made into cold water. The cold water is circulated to the indoor fan coil unit, .

1: low temperature compressor 2: pressure gauge
3: Four-way valve 4: Heat exchanger for cooling and defrosting
5: Cold expansion 1 5a: Cold expansion 2
6: Air Heat Exchanger 7: Cold Air Cooling
8: Discharge tube 9:
10: High-temperature compressor 11: Heat storage heat exchanger
12: high-temperature inflation side 13:

Claims (2)

Temperature side refrigerating cycle and a high-temperature side refrigerating cycle, wherein condensation of the low-temperature side low-temperature refrigerant and evaporation of the high-temperature side high-temperature refrigerant are performed in one cascade heat exchanger (A) A defrosting operation method of a heat pump apparatus using a two-way refrigeration cycle wherein defrosting occurs in an air heat exchanger (6) to defrost the defrosting to high temperature refrigerant discharged from the low temperature compressor (1)
(S4) stopping the heating operation when the outside air temperature is lower than or equal to the image temperature of 15 DEG C or the heating operation accumulation time exceeds 1 hour in the heating operation step (S1). If the heating operation is stopped, (S5) judging whether the outside air temperature is lower than -10 占 폚 to start the defrosting operation, (S6) judging whether the refrigerant pressure is 3.5 kg / cm2 or lower,
In the above steps, if the outside air temperature is -10 ° C or more and the refrigerant pressure is 3.5 kg / cm 2 or more, opening the solenoid valve 2 (B2) on the low temperature side to expand the refrigerant in the low temperature expansion side 2 S7),
(S8) of causing the refrigerant to be compressed to a high temperature in the low-temperature compressor (1) after the refrigerant is evaporated in the heat exchanger (4) on the low temperature side when the refrigerant is expanded in the step
(S9) causing defrosting to be performed while the refrigerant compressed at a high temperature is circulated to the air heat exchanger (6), and a step S10 of terminating the defrosting operation when 10 minutes have elapsed after setting the defrost operation time A defrosting operation method of a heat pump apparatus using a dual refrigeration cycle. The method according to claim 1,
If the outside air temperature is lower than -10 ° C or the refrigerant pressure is 3.5 kg / cm 2 or less, the low-temperature bypass valve B3 is opened so as not to pass through the step S7, The refrigerant is compressed in the low-temperature compressor (1) without expanding the refrigerant, so that the temperature of the refrigerant is rapidly raised so that the defrosting operation of the heat pump device Way.

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