WO2017163337A1 - Heat-pump-type heating apparatus - Google Patents

Abstract

A heat-pump-type heating apparatus (1) according to the present invention supplies heat to a heating terminal (70). The heat-pump-type heating apparatus (1) comprises a cooling cycle (10), a heat exchanging part (31), a heat dissipation part (32), and an air-blowing device (50). The cooling cycle (10) is configured such that a first coolant is circulated through a compressor (11), a condenser (12), an expansion valve (13), and an evaporator (14) in this order. The heat exchanging part (31) is configured to heat, by using heat from the condenser (12), a second coolant flowing to the heating terminal (70). The heat dissipation part (32) is configured to dissipate the heat of the second coolant flowing from the heating terminal (70) to the heat exchanging part (31). The air-blowing device (50) is configured to blow air from the heat dissipation part (32) to the evaporator (14).

Description

Heat pump heating system

The present invention relates to a heat pump type heating device.

In an apparatus equipped with a refrigeration cycle, when the temperature around the evaporator decreases, frost may be generated in the evaporator. It is known that when frost is generated in the evaporator, the heat exchange efficiency in the evaporator is lowered and the capacity of the refrigeration cycle is lowered. Therefore, some apparatuses having a refrigeration cycle have a configuration in which a defrosting operation is performed in order to remove frost generated in an evaporator. For example, Japanese Patent Laying-Open No. 2008-96044 (Patent Document 1) discloses a hot water storage type hot water supply apparatus that heats an evaporator with warm water from a hot water storage tank as a defrosting operation.

JP 2008-96044 A

During the defrosting operation, normal operation of the refrigeration cycle is often not performed in order to stop heat absorption by the evaporator and complete the defrosting quickly. If the defrosting operation is frequently performed, normal operation is hindered, and thus the user's comfort may be impaired.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a heat pump heating device that can suppress the generation of frost in the evaporator while continuing the heating operation. It is.

The heat pump heating device according to the present invention heats a room by supplying heat to a heating terminal. The heat pump heating device includes a refrigeration cycle, a heat exchange unit, a heat radiating unit, and a blower. The refrigeration cycle is configured to circulate the first refrigerant in the order of the compressor, the condenser, the expansion valve, and the evaporator. A heat exchange part is comprised so that the 2nd refrigerant | coolant which flows into a heating terminal may be heated using the heat | fever from a condenser. The heat radiating unit is configured to release heat of the second refrigerant flowing from the heating terminal to the heat exchange unit. The blower is configured to blow air from the heat radiating unit to the evaporator.

According to the present invention, the residual heat of the second refrigerant during the heating operation can be used for heating the evaporator. Therefore, the evaporator can be heated while continuing the heating operation to suppress the generation of frost, and the user's comfort can be improved.

It is a functional block diagram which shows the structure of the heat pump type heating apparatus which concerns on embodiment. FIG. 6 is a Ph diagram showing the relationship between the pressure of the primary refrigerant circulating in the refrigeration cycle and enthalpy. It is a figure for comparing the heating capability of a heat pump type heating device, and a coefficient of performance COP (Coefficient Of Performance). It is a flowchart for demonstrating the process which controls the switching valve performed by a control apparatus. It is a functional block diagram which shows the structure of the heat pump type heating apparatus which concerns on the modification of embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

FIG. 1 is a configuration diagram of a heat pump heating device 1 according to an embodiment. As shown in FIG. 1, the heat pump heating device 1 includes a refrigeration cycle 10, a pump 20, a cooler 32, a switching valve 40, a fan 50, and a control device 100.

The refrigeration cycle 10 includes a compressor 11, a condenser 12, an expansion valve 13, and an evaporator 14. In the refrigeration cycle 10, the primary refrigerant circulates in the order of the compressor 11, the condenser 12, the expansion valve 13, and the evaporator 14. A heat exchanger 31 is incorporated in the condenser 12.

The primary refrigerant (for example, R32) releases heat to the secondary refrigerant that passes through the heat exchange unit 31 in the condenser 12. The secondary refrigerant that has received heat from the primary refrigerant is output to the heating terminal 70 (for example, a fan coil or a radiator) by the pump 20. The heating terminal 70 is warmed by the heat released from the secondary refrigerant. The secondary refrigerant that has released heat to the heating terminal 70 returns to the condenser 12, receives heat from the primary refrigerant again, and is output to the heating terminal 70 by the pump 20.

The cooler 32 is connected to the heat exchange unit 31 and the heating terminal 70. A switching valve 40 is connected in the middle of the flow path that branches from the flow path connecting the cooler 32 and the heating terminal 70 and is connected to the heat exchange unit 31.

The secondary refrigerant is, for example, water or brine. Brine is an antifreeze having a freezing point lower than 0 ° C., and includes, for example, a sodium chloride aqueous solution, a calcium chloride aqueous solution, or an ethylene glycol aqueous solution. By using a brine having a lower freezing point than water as the secondary refrigerant, freezing in the piping can be suppressed.

The compressor 11 compresses and outputs a gaseous primary refrigerant (gas refrigerant) from the evaporator 14. The drive frequency of the compressor 11 is controlled by the control device 100, and the amount of refrigerant discharged per unit time is controlled.

In the condenser 12, the high-temperature and high-pressure gas refrigerant from the compressor 11 is cooled and condensed, and a liquid primary refrigerant (liquid refrigerant) is output. The condenser 12 releases heat (condensation heat) when the gas refrigerant is condensed to the secondary refrigerant.

The expansion valve 13 adiabatically expands the liquid refrigerant from the condenser 12 to reduce the pressure. The opening degree of the expansion valve 13 is adjusted by the control device 100. The primary refrigerant decompressed by the expansion valve 13 is in a gas-liquid two-phase state (wet steam). The expansion valve 13 is, for example, an electronically controlled expansion valve (LEV: Linear Expansion Valve).

The evaporator 14 receives heat from the outside air through heat exchange, and evaporates the liquid refrigerant contained in the wet steam from the expansion valve 13. A gas refrigerant is output from the evaporator 14. The evaporator 14 takes heat (evaporation heat) from the surrounding air and evaporates the liquid refrigerant.

The fan 50 promotes the air flow from the cooler 32 to the evaporator 14 by blowing air. The fan 50 may be arranged to blow air to the cooler 32 as shown in FIG. 1 or may be arranged to suck air from the evaporator 14.

The control device 100 controls the opening degree of the expansion valve 13 so that, for example, the superheat degree of the refrigerant output from the evaporator 14 approaches the target superheat degree (superheat degree control). The control device 100 controls the pump 20 to output the secondary refrigerant to the heating terminal. The control device 100 controls the drive frequency of the compressor 11 so that the temperature of the refrigerant that has passed through the condenser 12 becomes a constant temperature, and adjusts the amount of refrigerant that is output from the compressor 11 per unit time. To do. The control device 100 controls the fan 50 and sends air to the cooler 32. The control device 100 controls opening and closing of the switching valve 40. The control device 100 receives the temperature around the evaporator 14 from the temperature sensor 60. Even when the heating operation of the heat pump heating device 1 is stopped, the control device 100 circulates the secondary refrigerant intermittently to prevent the secondary refrigerant from freezing.

When the temperature around the evaporator decreases, frost may be generated in the evaporator. It is known that when frost is generated in the evaporator, the heat exchange efficiency in the evaporator is lowered and the capacity of the refrigeration cycle is lowered. In such a case, the heat pump heating device performs a defrosting operation for removing frost generated in the evaporator. Examples of the defrosting operation include a method of reversing the circulation of the primary refrigerant in the refrigeration cycle or using hot water heated by a heating terminal.

During the defrosting operation, the normal operation of the refrigeration cycle 10 is normally stopped in order to stop heat absorption by the evaporator and complete the defrosting quickly. If the defrosting operation is frequently performed, the continuation of the heating operation is hindered, and thus the user's comfort may be impaired.

Therefore, in the embodiment, the evaporator 14 is heated using the residual heat of the secondary refrigerant during the heating operation, and the generation of frost in the evaporator 14 is suppressed. As a result, heating operation can be performed continuously, and user comfort can be improved.

In the embodiment, the secondary refrigerant returned from the heating terminal 70 returns to the condenser 12 after passing through the cooler 32 when the switching valve 40 is closed. The cooler 32 cools the secondary refrigerant. The secondary refrigerant releases heat when passing through the cooler 32. The air warmed by the heat is blown to the evaporator 14 by the fan 50. The evaporator 14 is heated by the air.

When the switching valve 40 is open, the flow path passing through the cooler 32 has a higher flow path resistance than the flow path passing through the switching valve 40, so that most of the secondary refrigerant returned from the heating terminal 70 is switched. It is input to the condenser 12 via the valve 40. When the switching valve 40 is open, the evaporator 14 is hardly heated by the secondary refrigerant.

In the embodiment, when the switching valve 40 is closed, the cooler 32 further takes heat from the secondary refrigerant that has released heat to the heating terminal 70, and the evaporator 14 is heated using the heat. The temperature of the secondary refrigerant input to the condenser 12 is lower when the switching valve 40 is closed than when the switching valve 40 is open. When the switching valve 40 is closed, in order to make the temperature of the secondary refrigerant output to the heating terminal 70 the same as that when the switching valve 40 is open, condensation is performed more than when the switching valve 40 is open. It is necessary to give much heat to the secondary refrigerant in the vessel 12. That is, the enthalpy of the primary refrigerant passing through the evaporator 14 needs to be larger when the switching valve 40 is closed than when the switching valve 40 is open. Therefore, the compressor 11 of the refrigeration cycle 10 is controlled by the control device 100 so that the amount of work (energy) performed on the primary refrigerant is higher when the switching valve 40 is closed than when the switching valve 40 is open. Be controlled.

FIG. 2 is a Ph diagram showing the relationship between the pressure of the primary refrigerant circulating in the refrigeration cycle 10 and enthalpy. In FIG. 2, a curve LC is a saturated liquid line of the primary refrigerant. A curve GC is a saturated vapor line of a single primary refrigerant. Point CP is the critical point of the primary refrigerant.

The critical point is a point indicating a limit of a range in which a phase change can occur between the liquid refrigerant and the gas refrigerant, and is an intersection of the saturated liquid line and the saturated vapor line. When the pressure of the primary refrigerant becomes higher than the pressure at the critical point, no phase change occurs between the liquid refrigerant and the gas refrigerant. In the region where the enthalpy is lower than the saturated liquid line, the primary refrigerant is liquid, and in the region where the enthalpy is higher than the saturated vapor line, the primary refrigerant is a gas. In the region sandwiched between the saturated liquid line and the saturated vapor line, the primary refrigerant is in a gas-liquid two-phase state (wet steam).

Referring to FIG. 2, when the switching valve 40 is open (when the evaporator 14 is not heated by the secondary refrigerant), the circulation of the primary refrigerant is from point R11 to point R12, point R13, and point. It is represented as a cycle C1 (broken line) that returns to point R11 via R14. The state change from the point R11 to the point R12 represents the process of compression of the primary refrigerant by the compressor 11. The state change from the point R12 to the point R13 represents the process of condensing the primary refrigerant by the condenser 12. The state change from the point R13 to the point R14 represents the process of adiabatic expansion of the primary refrigerant by the expansion valve 13. The state change from the point R14 to the point R11 represents the process of evaporation of the primary refrigerant by the evaporator 14.

When the switching valve 40 is closed (when the evaporator 14 is heated by the secondary refrigerant), the circulation of the primary refrigerant returns from the point R21 to the point R21 via the points R22, R23, and R24. Represented as the coming cycle C2 (solid line). The state change from the point R21 to the point R22 represents the process of compression of the primary refrigerant by the compressor 11. The state change from the point R22 to the point R23 represents the process of condensing the primary refrigerant by the condenser 12. The state change from the point R23 to the point R24 represents the process of adiabatic expansion of the primary refrigerant by the expansion valve 13. The state change from the point R24 to the point R21 represents the process of evaporation of the primary refrigerant by the evaporator 14.

Comparing the cycle C1 when the switching valve 40 is open and the cycle C2 when the switching valve 40 is closed, the state of the point R22 is the point R21 with respect to the end point of the adiabatic compression process by the compressor 11. Both the enthalpy and pressure are higher than the state of. This is a result of the compressor 11 being controlled by the control device 100 so as to compress the primary refrigerant when the switching valve 40 is closed rather than when it is open.

Also, regarding the end point of the condensation process by the condenser 12, the state at the point R23 has a smaller enthalpy than the state at the point R13. This is because when the switching valve 40 is closed, the secondary refrigerant returned from the heating terminal 70 passes through the cooler 32, so that the temperature of the secondary refrigerant input to the condenser 12 is low. Lower than if you are. The primary refrigerant that has passed through the condenser 12 is cooled when the switching valve 40 is closed rather than when the switching valve 40 is open. As a result, the degree of supercooling is higher when the switching valve 40 is closed than when the switching valve 40 is open, and the enthalpy is smaller at the point R23 than at the point R13. .

Thus, when the evaporator valve 14 is heated using the secondary refrigerant with the switching valve 40 closed, the amount of work (energy) performed by the compressor 11 on the primary refrigerant increases. That is, the energy consumed by the heat pump heating device 1 increases. Therefore, if the switching valve 40 is closed and the evaporator 14 is heated using the secondary refrigerant, the efficiency of the heat pump heating device 1 is lowered. So, in embodiment, when the heating capability of the heat pump type heating apparatus 1 can be improved by suppressing generation | occurrence | production of frost, the switching valve 40 is closed and the evaporator 14 is heated.

FIG. 3 is a diagram for comparing the heating capacity of the heat pump type heating device 1 with a coefficient of performance COP (Coefficient Of Performance). In the embodiment, the heating capacity of the heat pump heating device 1 is the amount of heat that the heating terminal receives from the secondary refrigerant. In the embodiment, the COP of the heat pump heating device 1 is a ratio between the heating capacity and the energy given to the primary refrigerant by the compressor 11 and is an index indicating the efficiency of the heat pump heating device 1. The graph shown in FIG. 3 can be obtained by actual machine experiments or simulations.

FIG. 3A is a diagram showing the relationship between the heating capacity and the temperature around the evaporator 14. In FIG. 3A, a curve PN indicates a case where it is assumed that no frost is generated in the evaporator 14. A curve PC indicates a case where the switching valve 40 is closed. A curve PO shows a case where the switching valve 40 is open. As shown in FIG. 3A, when the temperature T around the evaporator 14 is between the temperature T1 and the temperature T2 (T1 <T <T2), the heating capacity is when the switching valve 40 is closed. Is larger than when it is open. On the other hand, when the temperature T is lower than the temperature T1, the humidity is low, so that the evaporator 14 is unlikely to generate frost. Therefore, the heating capacity hardly changes between when the switching valve 40 is closed and when it is open. Further, when the temperature T is higher than the temperature T2, the temperature is sufficiently higher than 0 ° C., which is the freezing point of water, so that the heating capacity hardly changes between when the switching valve 40 is closed and when it is open.

FIG. 3B is a diagram showing the relationship between the COP and the ambient temperature of the evaporator 14. In FIG.3 (b), the curve EN shows the case where it assumes that frost does not generate | occur | produce in the evaporator 14. FIG. A curve EC indicates a case where the switching valve 40 is closed. A curve EO indicates a case where the switching valve 40 is open. As shown in FIG. 3B, the COP when the switching valve 40 is closed is lower than the COP when the switching valve 40 is open. That is, if the switching valve 40 is closed and the evaporator 14 is heated using the residual heat of the secondary refrigerant, the efficiency of the heat pump heating device 1 decreases.

As shown in FIG. 3, although the COP (FIG. 3 (b)) decreases, the heating capacity (FIG. 3 (a)) is improved because the temperature T around the evaporator 14 is changed from the temperature T1 to the temperature T2. This is a case where there is an interval (T1 <T <T2). Therefore, in the embodiment, when the temperature T around the evaporator 14 is between the temperature T1 and the temperature T2 (T1 <T <T2), the switching valve 40 is closed and the cooler 32 is used as the secondary refrigerant. The evaporator 14 is heated through.

FIG. 4 is a flowchart for explaining processing for controlling opening and closing of the switching valve 40 performed by the control device 100. The process shown in FIG. 3 is performed by a main routine (not shown) executed by the control device 100 for controlling the heat pump heating device 1.

As shown in FIG. 4, in step (hereinafter simply referred to as S) S101, the control device 100 measures the temperature T around the evaporator 14 with the temperature sensor 60, and advances the process to S102. In S102, the control device 100 determines whether or not the temperature T is higher than the reference temperature T1 and lower than the reference temperature T2. When temperature T is higher than reference temperature T1 and lower than reference temperature T2 (YES in S102), control device 100 closes switching valve 40 and warms evaporator 14 in S103 to suppress the generation of frost. Return processing to the main routine. When temperature T is lower than reference temperature T1 or higher than reference temperature T2 (NO in S102), control device 100 opens switching valve 40 in S104 and stops heating evaporator 14.

By performing the above-described processing, the COP is lowered by cooling the secondary refrigerant in the cooler 32. The temperature T around the evaporator 14 is between the temperature T1 and the temperature T2 (T1 <T <T2). It can be limited to the case.

As described above, according to the embodiment, generation of frost in the evaporator 14 can be suppressed while continuing the heating operation. As a result, heating operation can be performed continuously, and user comfort can be improved.

In the embodiment, the case where the condenser 12 and the heat exchange unit 31 are integrated has been described. The heat exchange unit 31 may be separated from the condenser 12.

In the embodiment, the case where the switching valve 40 is provided has been described. The switching valve 40 is not an essential component in the present invention. For example, the secondary refrigerant returned from the heating terminal may be input to the cooler 32 without including the switching valve 40 as in the heat pump heating device 1A shown in FIG. According to the heat pump heating device 1A, since the switching valve is unnecessary, the manufacturing cost can be suppressed.

In the embodiment, a case has been described in which the evaporator 14 is heated by controlling the switching valve 40 to be closed in a temperature range in which the heating capacity of the heat pump heating device 1 decreases due to the generation of frost. It is known that the amount of frost generated in the evaporator 14 also depends on the humidity around the evaporator 14. Therefore, the switching valve 40 may be controlled based on the humidity around the evaporator 14. Alternatively, the switching valve 40 may be controlled based on the temperature and humidity around the evaporator 14.

In addition, by reducing the ventilation resistance in the evaporator 14, the air from the cooler 32 blown by the fan 50 can easily reach the entire evaporator 14, and the evaporator 14 can be heated more efficiently. it can. For example, the ventilation resistance of the evaporator 14 can be reduced by making the fin pitch of the cooler 32 larger than the fin pitch of the evaporator 14. Or the ventilation resistance of the evaporator 14 in suppressing the raising and raising of the fin of the cooler 32 from the raising and raising of the fin of the evaporator 14 can be reduced.

The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1,1A heat pump heating device, 10 refrigeration cycle, 11 compressor, 12 condenser, 13 expansion valve, 14 evaporator, 20 pump, 31 heat exchange section, 32 cooler, 40 switching valve, 50 fan, 70 heating terminal , 100 control unit, T1, T2 reference temperature.

Claims (3)

A heat pump heating device for supplying heat to a heating terminal,
A refrigeration cycle configured to circulate a first refrigerant in the order of a compressor, a condenser, an expansion valve, and an evaporator;
A heat exchange section configured to heat the second refrigerant flowing to the heating terminal using heat from the condenser;
A heat radiating section configured to release heat of the second refrigerant flowing from the heating terminal to the heat exchange section;
A heat pump heating device comprising: a blower configured to blow air from the heat radiating unit to the evaporator. A bypass unit configured to supply the second refrigerant from the heating terminal to the heat exchange unit without passing through the heat dissipation unit;
When the temperature around the evaporator is within a predetermined range, the bypass unit does not supply the second refrigerant to the heat exchange unit, and when the temperature is outside the predetermined range, The heat pump heating device according to claim 1, configured to supply a refrigerant to the heat exchange unit. The heat pump heating device according to claim 1, wherein the second refrigerant is brine.

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