KR101058843B1 - Defrost heat pump cycle - Google Patents

Abstract

The present invention provides a heat pump cycle in which there is no interruption of the heating operation during the defrosting operation and no deterioration in capacity even at the extreme outside temperature drop (for example, -20C). When the outside temperature is below a certain temperature (eg T2, 0C), the auxiliary compressor is additionally applied so that the main compressor 301a mounted on the main cycle can be operated within the normal operation range. Control not to. That is, by controlling the evaporation pressure of the low-temperature corresponding heat exchanger 208 in the main cycle to a predetermined pressure or more by using a refrigeration compressor, which is an auxiliary compressor 301b in the auxiliary cycle, the heating capacity is not lowered and the main compressor 301a is damaged. To prevent. In addition, the low-temperature corresponding heat exchanger 308 serving as the evaporator of the main cycle does not come into contact with the outside air and thus there is no possibility of dropping. Between the auxiliary cycle and the main cycle is applied a thermal equilibrium closed circuit for supplying heat to the auxiliary cycle evaporator 312 using a working fluid such as brine. In addition, in the case of the auxiliary cycle evaporator 312, by applying a plate-shaped heat exchanger so as not to contact the outside air, it is possible to fundamentally prevent the build-up on the evaporator 212 in the auxiliary cycle.

Heat Pump Refrigerant Circuit, Auxiliary Cycle, Heat Balanced Closed Circuit, Fin Tube Type Brine Heat Exchanger, Plate Type Brine Heat Exchanger, Defrost, Defrost, Low Temperature Heat Exchanger

Description

Defrosting heat pump (Hot water generation) cycle

The present invention relates to a heat pump type cycle for heating by using an air heat source, and relates to improvements in capacity degradation and comfort caused by defrosting operation that may occur when the temperature of the air heat source is lowered.

As shown in FIG. 1, a conventional heat pump includes a compressor 101 for compressing a refrigerant gas, a four-sided valve 102 capable of changing a circulation direction of the refrigerant, a condenser 103 for condensing the compressed refrigerant gas, and condensation. A decompression device 105 for cooling the refrigerant liquid under reduced pressure and an evaporator 106 for evaporating the decompressed refrigerant completely in a gas state.

By changing the refrigerant circulation direction through the four sides 102 may be obtained through a system for cooling or heating, it may be configured to only perform the cooling operation or heating operation.

In the case of a conventional air heat source heat pump, when the outside air is lowered below a certain temperature and the evaporation temperature is lowered (-15 C in the case of R22), a high condensation temperature (about 55 C in the case of R22) is maintained to ensure user comfort. If the system continues to operate, as shown in FIG. 2, the compressor performs a high compression ratio operation that is out of the normal operation range, causing problems such as an increase in discharge temperature and oil carbonization, which leads to burnout of the compressor unless proper operation restriction is performed. do.

In order to protect the system, if the condensation temperature is lowered within the safe operation range of the compressor, that is, in the case of R22 refrigerant, if the condensation temperature is limited to 45C from the evaporation temperature of -15C, Likewise, when the outside air temperature is severely reduced in winter (for example, Seoul -15C), it becomes difficult to secure the user's comfort.

In addition, when the outside air temperature decreases during the operation of the heat pump, the moisture in the outside air is removed from the evaporator in the form of a drop of water due to the correlation between the outside temperature and the evaporator coil temperature. This can cause a problem such as liquid back.

In the case of a heat pump system using an air heat source, a defrosting operation is required to eliminate system problems caused by frost generated on the surface of the evaporator coil when the outside temperature is low, and it is usually necessary to bypass the discharge gas or the heater to the evaporator side. Defrost operation is carried out after installation.

In addition, as the outside temperature is lowered, not only the compressor system capacity is lowered, but also the heating operation during defrosting operation is generally not performed. Therefore, an electric heating coil having low energy efficiency is installed on the indoor unit side to compensate for this.

Patent No. 10-2003-0066432 filed using two refrigerant cycles has been registered to solve the problem caused by the decrease in system capacity during heating operation. However, in this system, the auxiliary heat pump used to increase the compressor suction temperature. The evaporator in the system is exposed to the outside air and cannot be free from defrost problems and reduced heating capacity.

Also, in case of 10-2006-0029840, which has applied a brine system and a combined cycle to a heat pump, for a system in which air-conditioning is continuously operated for a year, the air-conditioning and the brine are reduced by using air and brine, and the compressor is controlled by the number of years to save energy. As a system to improve efficiency, it does not solve any problems (defrost, compressor reliability, deterioration, etc.) caused by the decrease in the outside air temperature mentioned at the outset.

The present invention solves problems such as a decrease in capacity due to a temperature drop of a heat source generated from an existing air heat source hot water generator or a heat pump, a problem caused by defrosting, and a decrease in compressor reliability, thereby maximizing user comfort during hot water production or heating operation. To provide a cycle.

In the present invention, when the outside temperature decreases (eg, 0C), the auxiliary cycle is operated to increase the evaporation temperature in the low-temperature corresponding heat exchanger 208 in the main cycle, thereby preserving system capacity loss due to the decrease in the outside temperature. In addition, according to the outside conditions, the outside temperature is applied by applying a heat balance closed circuit that obtains heat from the plate type brine heat exchanger 304b or the fin tube type brine heat exchanger 304a in the main cycle and supplies heat to the secondary cycle evaporator 312. Even if the outdoor unit heat exchanger 307 is low and the normal heating operation is not possible, the heating operation or the hot water production is possible without stopping the operation or reducing the capacity in the main cycle.

The present invention is further applied to the auxiliary cycle and the thermal equilibrium closed circuit to the main cycle for producing hot water or heating operation using the heat pump cycle, there is an effect that can prevent the decrease in capacity due to the decrease in the outside temperature, thermal equilibrium By providing a closed circuit, even when the defrosting operation in the main circuit is required, the normal heating operation is enabled by the operation of only the heat balanced closed circuit or the operation of the auxiliary cycle. In addition, even when the outside air temperature was lowered to the point where normal heating operation was not possible (eg -10C), the auxiliary cycle was operated to allow the system to be operated without interrupting the heating operation. The low-temperature corresponding heat exchanger 308 in the main cycle applies a plate heat exchanger type capable of receiving heat from the high-temperature refrigerant gas discharged through the sub-compressor 301b, which is a low-temperature compressor in the sub-cycle, to contact the outside air. Removed. The two-phase refrigerant in the auxiliary cycle evaporator 312 is a low-temperature corresponding heat exchanger in the form of a brine and a plate heat exchanger supplied with heat through a fin tube-type brine heat exchanger 304a or a plate brine heat exchanger 304b in a thermal equilibrium closed circuit ( The heat exchange in 308 allows the design of a system in which contact with the outside air is essentially removed.

The terms or words used in this specification and claims are not to be construed as being limited to their ordinary or dictionary meanings, and the inventors may appropriately define the concept of terms in order to best describe their invention. It should be interpreted as meaning and concept corresponding to the technical idea of the present invention based on the principle that the present invention.

Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

Since the general air-conditioning cycle of the heat pump according to the present invention is the same as the conventional one, it is omitted. The following describes the low-temperature heating operation in the main cycle that enables normal heating operation without a heating auxiliary device under contact heating operation and a certain outside temperature (e.g. T2), which is not normally possible.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a configuration diagram of a heat pump cycle according to the present invention, and is mainly composed of a main cycle, an auxiliary cycle, and a thermal balanced closed circuit. Table 1 summarizes the operation of each cycle according to the ambient temperature and the temperature conditions in each cycle under constant ambient conditions. In addition, overall cycle operation control is summarized in the flowchart of FIG. The operation method can be roughly divided into general heating operation, non-contact heating operation, and low temperature heating operation according to the heat balance closed circuit, auxiliary cycle, and main cycle operation according to the outside temperature.
[Table 1] Operation status and operation method according to outside temperature
Driving method

Operation status
General heating operation
Outside contactless heating operation
Low temperature heating operation
Ambient temperature [C] lowest Best lowest Best lowest T1 T1 T2 T2 T3
Thermal equilibrium
Closed circuit
Driving Fin Tube Type X O O Plate type X △ △ Brine outlet temperature [C] T1 T1 T2 T2 T3-3 Brine inlet temperature [C] T1-5 T1-5 T2-5 T2-5 T3-8
assistant
cycle Driving X X O Evaporation Temperature [C] - - - T2-10 T3 =-13 Condensation temperature [C] - - - T4 T4
Main cycle
Driving O O O Evaporation Temperature [C] T1-5 T1-10 T2-10 T4-10 T4-10 Condensation temperature [C] T5 T5 T5 T5 T5
Whether to run: O (always), X (stop), △ (intermittent)

In the case of the main cycle, it is shown in FIG. Normal heating operation applied when outside air is above a certain temperature (eg T1, 5C), contactless heating operation applied when outside air is less than T1, low temperature heating operation applied when outside air is below T2 (eg 0C) Can be. In the case of the general heating operation, since it is a well-known configuration such as the general heating expansion valve 506a (306a (shown in FIG. 3)), a separate configuration will not be described. As shown in FIG. 5 and Table 1, the external contactless heating operation or the low temperature heating operation includes a main compressor 501a for compressing the refrigerant in the main cycle and a refrigerant compressed from the main compressor 501a with the liquid refrigerant. The load side heat exchanger 503 and the load 510 such as air, water, or process liquid required by the user in the outdoor unit heat exchanger 507, and heat supply to the low temperature brine in the thermal equilibrium closed circuit from the air heat source. The plate-shaped brine heat exchanger 504b serving as a heat supply to the low temperature brine by using the high temperature condensed refrigerant from the fin tube type brine heat exchanger 504a and the load side heat exchanger 503, and the electric heating valve 505a for general heating operation. ), The low-temperature heating electronic valve (505b) that controls the refrigerant circulation direction so as to enable external air contactless heating or low-temperature heating operation, and expands the liquid refrigerant into two-phase refrigerant Low temperature heating expansion valve (506b) and low-temperature response to enable the heat exchange between the high-pressure refrigerant gas discharged from the operating fluid in the thermal equilibrium closed circuit or the auxiliary compressor in the auxiliary cycle during the low temperature heating operation The heat exchanger 508 and the check valve 509b which serve to pass only the refrigerant which passed through the low temperature corresponding heat exchanger 508 into a main cycle are comprised.

delete

Auxiliary cycle is shown in Figure 6, the secondary compressor (601b) capable of compressing the refrigerant at low evaporation temperature (e.g., -25C in case of R404), and the high-temperature and high-pressure refrigerant gas compressed heat exchanged with the two-phase refrigerant in the main cycle And a low-temperature corresponding heat exchanger 608, a subsidiary cycle expansion valve 606d, and a subsidiary cycle evaporator 612 condensed by liquid refrigerant. The operation range for this auxiliary compressor is shown in Figure 8, the operating evaporation temperature range, unlike in Figure 2, it is possible to operate stable at low evaporation temperature (eg -30C). In addition, since the high temperature refrigerant gas is condensed through the working fluid in the thermal equilibrium closed circuit, a low condensation temperature can be maintained.

The thermal equilibrium closed circuit for supplying heat to the evaporator in the auxiliary cycle is shown in Figure 7, the configuration is a pump 713 for circulating the working fluid, such as brine, and the brine for controlling the flow path of the working fluid according to the temperature conditions Through the temperature-changing switching valve 714b, the fin tube type brine heat exchanger 704a for supplying heat from the outside air to the working fluid in the thermal equilibrium closed circuit, and the fin tube type brine heat exchanger 704a due to the drop in outside temperature The plate-type brine heat exchanger 704b receives auxiliary heat from the main cycle when it cannot supply sufficient heat to the working fluid, and the fin tube-type brine heat exchanger 704a and the plate brine are supplied to the low-temperature, low-pressure two-phase refrigerant in the auxiliary cycle. It consists of the subcycle evaporator 712 which supplies the heat acquired through the heat exchanger 704b.

The operation of the present invention configured as described above will be described in detail with reference to FIG. 3 as follows.

When the outside air temperature is present between T1 and T2 as shown in Table 1, after closing the electric heating valve 305a for general heating, the low-temperature heating electronic valve 305b is opened so as to be in contact with the outside air in the main cycle. In the case of external contactless heating operation, the thermal equilibrium closed circuit shall be applied as specified in Table 1. That is, the low-temperature heating electronic valve 305b in the main cycle is opened, and the high-temperature, high-pressure refrigerant liquid flowing through the load-side heat exchanger 303 flows to the low-temperature corresponding heat exchanger 308 so as to be in contact with the outside air. At the same time, the pump 313 in the thermal equilibrium closed circuit is operated to circulate the working fluid so that the working fluid and the refrigerant can exchange heat in the low temperature corresponding heat exchanger 308. In addition, the valve opening degree of the auxiliary cycle operation switching valve 314a is changed to prevent the working fluid from circulating toward the auxiliary cycle. In the external contactless heating operation, the refrigerant circulation sequence in the main cycle includes the main compressor (301a)-the four sides (302)-the load side heat exchanger (303)-the low temperature heating operation solenoid valve (305b)-the low temperature heating operation expansion valve (306b). -Low temperature response heat exchanger (308)-Four sides (302)-The main compressor (301a) in the order of circulation, and at the same time the circulation order of the working fluid, such as brine of the thermal equilibrium closed circuit pump 313-Brine rise valve (314b)-plate heat exchanger (304b) / fin tube heat exchanger (304a)-low temperature corresponding heat exchanger (308)-auxiliary cycle operation switching valve (314a)-it is circulated through the pump (313).
When the temperature measured by the fin tube brine heat exchanger inlet temperature sensor 315e is lower than the outside dew point temperature (e.g., T1-5), the opening of the brine rise valve 314b is adjusted to operate the plate brine heat exchanger 304b. By circulating, the temperature of the working fluid introduced into the fin tube brine heat exchanger (304a) is adjusted to be above the dew point temperature, so that no dropping occurs in the fin tube brine heat exchanger (304a).
The operating fluid heated up through the plate-shaped brine heat exchanger 304b and the fin tube-type brine heat exchanger 304a is mainly connected to the plate-type low temperature corresponding heat exchanger 308 in which the contact with the outside air, which serves as the evaporator in the main cycle, is removed. Heat exchange with the refrigerant in the cycle eliminated the possibility of potential buildup.
When the outside air temperature reaches T1 or higher during the outside air contact heating operation, it returns to the normal heating operation. When the outside temperature falls below T2, a low temperature heating operation that uses an auxiliary cycle is formed.

If it is judged that normal heating operation is not possible because the outside temperature drops below T2, the system is controlled to operate at low temperature. In addition to the main cycle, the auxiliary cycle and the pump in the thermal equilibrium closed circuit are operated to control the system to make it fully operational. In the case of low-temperature heating operation, the refrigerant circulating order in the main cycle is the same as the external contactless heating operation described above, and thus, further description thereof is omitted. However, in the case of the working fluid in the thermal balanced closed circuit, the heat acquired through the fin tube-type brine heat exchanger 304a and the plate-shaped brine heat exchanger is supplied to the auxiliary cycle evaporator 312 instead of the low temperature corresponding heat exchanger 308. That is, the circulation sequence of the working fluid in the thermal equilibrium closed circuit pump 313-brine rise valve 314b-plate type brine heat exchanger 304b / fin tube type heat exchanger 304a-auxiliary cycle evaporator 312-auxiliary cycle The operating fluid is circulated in the order of the operation switching valve 314a-the pump 313. In the case of the auxiliary cycle refrigerant, heat is supplied from the auxiliary cycle evaporator 312 from an operating fluid such as brine to supply heat to the low temperature corresponding heat exchanger 308 in the main cycle. The refrigerant circulation sequence in the auxiliary cycle circulates in the order of the auxiliary compressor 301b-the low temperature corresponding heat exchanger 308-the auxiliary cycle expansion valve 306d-the auxiliary compressor 301b.
The overall operation of the system for the low temperature heating operation according to Table 1 will be described. The low temperature heating expansion valve 206b is opened by closing the solenoid valve 305a for the general heating operation in the main cycle and opening the solenoid valve 305b for the low temperature heating operation. Through the two-phase refrigerant is circulated to the low temperature corresponding heat exchanger (308). At the same time, the secondary cycle is operated so that the high temperature and high pressure refrigerant gas discharged from the subcompressor 301b performs heat exchange with the low temperature low pressure two-phase refrigerant passed through the low temperature heating expansion valve 306b in the low temperature corresponding heat exchanger 308. do. In the low temperature response heat exchanger 308, the high temperature refrigerant gas in the auxiliary cycle condenses into the liquid phase, and the two phase refrigerant in the main cycle evaporates to the gas phase to pass through the check valve 309b and the four sides 302 for the low temperature heating operation. It is recovered to form a cycle that is discharged back to the high-temperature, high-pressure refrigerant gas. The refrigerant in the auxiliary cycle that has passed through the low temperature corresponding heat exchanger 308 is condensed into the liquid phase, passes through the auxiliary cycle expansion valve 306d and the auxiliary cycle evaporator 312, and is converted into a low temperature low pressure refrigerant gas to be returned to the auxiliary compressor 301b. Form a cycle to be injected.

During the low temperature heating operation, the low-pressure low-pressure two-phase refrigerant passing through the auxiliary cycle evaporator 312 in the auxiliary cycle is vaporized from the auxiliary cycle evaporator 312 to the gas phase in the auxiliary cycle evaporator. To 312. The working fluid in the thermal equilibrium closed circuit uses brine or the like as a working fluid to prevent damage caused by freezing even when exposed to low temperature outside air, and the working fluid such as brine is heated to the two phase refrigerant through the auxiliary cycle evaporator 312 The temperature is lowered by supplying the temperature through the fin tube type brine heat exchanger or plate brine heat exchanger to increase the temperature of the brine. That is, when the brine inlet temperature measured by the fin tube type heat exchanger brine inlet temperature sensor 315b is lower than the outside dew point temperature, the opening degree of the three-way brine temperature rising valve 214b is adjusted to pass through the plate brine heat exchanger 304b. The brine temperature rising valve 214b is adjusted to be introduced into the fin tube brine heat exchanger 304a above the outside dew point temperature. The brine heated up to the extent that no dropping occurs with the help of the plate-shaped brine heat exchanger 304b finally acquires heat through the fin tube brine heat exchanger 304a, and supplies heat to the secondary cycle evaporator 212 for circulation. . Excessive supercooling in the plate brine heat exchanger (304b) when the brine or the like heated up through the high temperature refrigerant in the main cycle in the plate brine heat exchanger (304b) heats the secondary cycle evaporator via the fin tube type brine heat exchanger (304a). In this case, the refrigerant liquid bypass solenoid valve 305c is opened to pass through the low temperature heating expansion valve 306b without passing through the plate brine heat exchanger 304b.

The brine temperature rising valve 314b in the thermal equilibrium closed circuit is a finned tube heat exchanger 304a or a plate brine heat exchanger by comparing the fin tube type heat exchanger brine inlet temperature with the outside temperature in an external contactless heating operation or a low temperature heating operation. 304b is controlled to circulate the brine. At the same time, by operating the main and auxiliary cycles, normal heating operation is possible even in extreme low temperature outdoor air (eg -17C).

Through the outside air temperature sensor, the outside air temperature condition is changed, and each operation mode is switched or stopped according to the outside air temperature condition according to Table 1. If it is judged that the compressor capacity is considerably lower than normal operation even during normal heating operation or external contactless heating operation (e.g. 70%), the auxiliary cycle is started regardless of the need for low temperature heating operation due to outdoor air. It is also possible to operate to raise the heating capacity more than a certain level regardless of the outside temperature by raising the.

1 is a conventional heat pump cycle

2 is a safe driving region of a typical scroll compressor currently on the market

3 is a heat pump cycle according to the present invention

Figure 4 is a cycle control flowchart of defrost and low temperature heating operation according to the present invention
5 is an enlarged cycle of only the main cycle of FIG.
6 is an enlarged cycle of only the auxiliary cycle in FIG.
FIG. 7 is an enlarged cycle of only the thermal balance closed circuit in FIG.
8 is a safe operation region of a typical refrigeration compressor currently on the market
<Explanation of symbols for the main parts of the drawings>
1a: main compressor
1b: auxiliary compressor
2: all sides
3: load side heat exchanger
4a: Fin Tube Type Brine Heat Exchanger
4b: plate brine heat exchanger
5a: Electronic valve for general heating operation
5b: Electronic valve for low temperature heating operation
5c: Refrigerant liquid bypass solenoid valve
6a: General heating expansion valve
6b: Low temperature heating expansion valve
6c: General cooling expansion valve
6d: auxiliary cycle expansion valve
7: outdoor unit heat exchanger
8: low temperature response heat exchanger
9a: Cooling operation check valve
9b: Low temperature heating check valve
10: load
11: outdoor unit fan
12: secondary cycle evaporator
13: pump
14a: auxiliary cycle operation switching valve
14b: brine temperature rising valve

Claims (3)

A main compressor for compressing a refrigerant, a load side heat exchanger for condensing the refrigerant compressed from the main compressor into a liquid refrigerant, a general heating operation electronic valve for allowing a refrigerant that has passed through the load side heat exchanger to flow during a normal heating operation, and for the general heating operation A main cycle refrigerant circuit to which a general heating expansion valve for expanding a liquid refrigerant having passed through an electron valve into a two-phase refrigerant, and an outdoor unit heat exchanger for cooling the refrigerant having passed through the general heating expansion valve by heat exchange; It is provided in the main cycle refrigerant circuit, the low-temperature heating operation electronic valve for adjusting the refrigerant circulation direction to enable the low-temperature heating operation in conjunction with the general heating operation electronic valve in preparation for low temperature outside air, passes through the low-temperature heating operation electronic valve Low pressure heating expansion valve for expanding a liquid refrigerant into a two phase refrigerant, high pressure discharged from the working fluid in the thermal equilibrium closed circuit or from the auxiliary compressor in the auxiliary cycle of the two phase refrigerant in the main cycle refrigerant circuit expanded by the low temperature heating expansion valve. A refrigerant circuit comprising a low temperature corresponding heat exchanger for exchanging heat with the refrigerant gas, and a check valve for passing only the refrigerant having passed through the low temperature corresponding heat exchanger into the main cycle; A subcompressor for supplying the heat of the refrigerant gas to the low temperature corresponding heat exchanger during the external contactless heating operation or the low temperature heating operation, and the high temperature and high pressure refrigerant gas compressed by the auxiliary compressor exchanges heat with the two phase refrigerant in the main cycle refrigerant circuit. A sub cycle refrigerant circuit comprising a sub cycle expansion valve for condensing with liquid refrigerant, and a sub cycle evaporator for evaporating the liquid refrigerant condensed by the sub cycle expansion valve; By circulating a working fluid such as brine in the thermal equilibrium closed circuit with a pump, heat is supplied to the auxiliary cycle evaporator in the auxiliary cycle through a fin tube type brine heat exchanger or a plate brine heat exchanger to heat the air or water or the process fluid without degrading its capacity. Supply heat pump or hot water production cycle. The auxiliary air conditioner according to claim 1, wherein in the outside air contactless heating operation, the heating operation is performed by using the low temperature corresponding heat exchanger in which contact with the outside air is blocked, and in the low temperature heating operation, the subsidiary is a refrigeration compressor together with the low temperature corresponding heat exchanger. Heat pump or hot water production cycle, characterized in that for supplying heat using the auxiliary cycle refrigerant circuit to which the compressor is applied. 2. The heat pump or hot water production cycle according to claim 1, wherein the thermal equilibrium closed circuit is applied using a fin tube brine heat exchanger or a plate brine heat exchanger to supply heat to the auxiliary cycle evaporator.

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