JP2010139098A - Refrigerating cycle device and water heater having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigerating cycle device capable of reducing the refrigerant required in operations including a defrosting operation, and preventing accumulation of the refrigerant and liquid back to an air heat exchanger. <P>SOLUTION: The air heat exchanger 6 is divided into air heat exchanger divided sections 6a, 6b, 6c, their inflow sides are respectively connected with a refrigerant pipe at a discharge side, of an electric expansion valve 4 through liquid opening/closing valves 5a, 5b, 5c, and the refrigerant pipe at a discharge side of a compressor 1 and the refrigerant pipe at the discharge side of the electric expansion valve 4 are connected through a hot gas valve 9. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vapor compression refrigeration cycle apparatus and a water heater equipped with the vapor compression refrigeration cycle apparatus, and in particular, to remove a refrigeration cycle apparatus for hot water supply that performs water heating using a water-refrigerant heat exchanger as a condenser. It relates to frost operation.

  In a refrigeration cycle apparatus for the purpose of water heating, a plate laminated heat exchanger, a double tube heat exchanger, or the like is often used as a condenser. These water-refrigerant heat exchangers are smaller than a plate fin tube air heat exchanger or the like normally used as an evaporator, and the internal volume occupied by the refrigerant flow path is small. The ratio of the liquid refrigerant to the entire volume of the refrigerant circuit including the is reduced. That is, if only the heating operation is considered, the amount of the enclosed refrigerant may be small.

  On the other hand, in general, the refrigeration cycle apparatus frosts the air heat exchanger that serves as an evaporator when the outside air is at a low temperature, so the high-temperature gas refrigerant discharged from the compressor is sent to the air heat exchanger. A defrosting circuit is provided. During this defrosting operation, the high-temperature gas refrigerant condenses and accumulates in the air heat exchanger, so there is a possibility that the refrigerant will run short on the low-pressure side. A large amount of refrigerant is enclosed in the refrigerant circuit. Therefore, there arises a problem that an abnormal operation in which the liquid refrigerant returns directly to the suction side of the compressor, that is, so-called liquid back easily occurs.

  In order to avoid the above problems, a heat pump type water heater is known that closes the condenser-side expansion valve and avoids liquid back after a predetermined time has elapsed since the start of the defrosting operation using the defrosting circuit. (For example, refer to Patent Document 1).

  In addition, by selectively switching between a circuit that sends high-temperature gas refrigerant discharged from the compressor directly to the evaporator inlet during defrosting operation and a circuit that sends it through the condenser, both liquid back and low-pressure abnormalities are reduced. A refrigerating apparatus that avoids the above is known (see, for example, Patent Document 2).

JP2003-222447A (6th page, FIG. 3) Japanese Patent No. 3343916 (5th page, FIG. 1)

However, in the heat pump type water heater according to Patent Document 1, the timing of the opening control of the expansion valve is based on the elapsed time from the start of defrosting, and it is detected whether the state is a liquid back state or a refrigerant shortage state. There is a problem that the reliability is low as a countermeasure.
Moreover, in any of the heat pump type hot water heater according to Patent Document 1 and the refrigeration apparatus according to Patent Document 2, it is assumed that the refrigerant accumulates in the air heat exchanger during the defrosting operation, and the heating operation is still performed. Therefore, the amount of the refrigerant to be filled is more than necessary.

  The present invention has been made in order to solve the above-described problems. Even when the defrosting operation is included, the required refrigerant amount is reduced, the liquid back is avoided, and the defrosting time is not prolonged. It is to provide a refrigeration cycle apparatus and a water heater equipped with the same.

  A refrigeration cycle apparatus according to the present invention includes a refrigerant circuit that forms a closed circuit by sequentially connecting a compressor, a water-refrigerant heat exchanger, a decompression unit, and an air heat exchanger with a refrigerant pipe, the compressor, and the water- A hot gas bypass path formed by connecting between the refrigerant heat exchanger and between the pressure reducing means and the air heat exchanger via a first opening / closing means, The exchanger has an internal refrigerant flow path divided into two or more systems, and at least one of the divided refrigerant flow paths has a second opening / closing means independently on each refrigerant flow path. And

  According to the refrigeration cycle apparatus of the present invention, if a sufficient amount of refrigerant is enclosed so that the water-refrigerant heat exchanger functions as a condenser, a refrigerant shortage state can be avoided and liquid back can be avoided. In addition, even when the liquid refrigerant is accumulated in the defrosting air heat exchanger, the refrigerant flowing into the compressor is insufficient and the defrosting time is not prolonged.

Embodiment 1 FIG.
(Overall configuration of refrigeration cycle equipment)
FIG. 1 is a circuit configuration diagram of a refrigeration cycle apparatus according to an embodiment of the present invention, and FIG. 2 is a three-dimensional configuration diagram of the refrigeration cycle apparatus.
1 and 2, the compressor 1 that compresses the refrigerant, the water-refrigerant heat exchanger 2 that releases heat from the gas refrigerant compressed by the compressor 1, and the refrigerant that has passed through the water-refrigerant heat exchanger 2 are expanded. The electric expansion valve 4 to be operated, the air heat exchanger 6 that evaporates the refrigerant expanded by the electric expansion valve 4, and the accumulator 8 that temporarily stores the refrigerant that has passed through the air heat exchanger 6 are sequentially connected by the refrigerant piping. A circulating refrigerant circuit is formed. In this refrigerant circuit, for example, R410A which is an HFC refrigerant is enclosed as a refrigerant. The refrigerant is not limited to R410A which is an HFC refrigerant, and other refrigerants such as carbon dioxide refrigerant or HFO1234yf may be enclosed. The water-refrigerant heat exchanger 2 has a water pipe 3, which is separated from the refrigerant circuit. The air heat exchanger 6 is divided into three air heat exchanger dividing parts 6a, 6b and 6c, and their inflow sides are respectively connected to the discharge side of the electric expansion valve 4 via liquid on-off valves 5a, 5b and 5c. It is connected to the refrigerant pipe, and it is possible to select whether or not each refrigerant flows through the air heat exchanger dividing sections 6a, 6b and 6c. As shown in FIG. 2, the air heat exchanger dividing portions 6a, 6b and 6c are divided into three in the vertical direction and are formed as an integral type. Temperature sensors 11a, 11b, and 11c are mounted on the refrigerant circuits on the gas refrigerant side of the three-divided air heat exchanger divisions 6a, 6b, and 6c, respectively. Further, the air heat exchanger 6 is provided with a blower 7 that promotes or adjusts the heat exchange, and an outdoor air temperature sensor 14 that detects the outside air temperature is attached in the vicinity of the blower 7. The refrigerant pipe on the discharge side of the compressor 1 and the refrigerant pipe on the discharge side of the electric expansion valve 4 are connected via a hot gas valve 9. In addition, on the refrigerant circuit on the discharge side of the electric expansion valve 4 and the hot gas valve 9 and on the inflow side of the liquid on-off valves 5a, 5b, and 5c, the temperature of the refrigerant that has passed through the electric expansion valve 4 and has become low pressure, etc. A low-pressure refrigerant temperature sensor 13 for detecting the above is attached.

  The water-refrigerant heat exchanger 2 is a plate stack type heat exchanger, and the volume of the refrigerant flow path is about 120 cc to 150 cc per 1 kW of heating capacity. On the other hand, the air heat exchanger 6 is a plate fin tube type having a heat transfer tube diameter of 8 mm and is about 300 cc to 500 cc per 1 kW of processing heat. Therefore, the internal volume of the refrigerant channel is water-refrigerant heat exchange. 2 times larger than the volume of the refrigerant flow path of the vessel 2. Therefore, the refrigerant flow path volume of each of the air heat exchanger divisions 6a, 6b and 6c divided into three in the air heat exchanger 6 is substantially the same as the refrigerant flow volume of the water-refrigerant heat exchanger 2 or It is smaller than that.

(Basic operation of refrigeration cycle equipment)
Next, the basic operation during the water heating operation of the refrigeration cycle apparatus configured as described above will be described.
The high-temperature and high-pressure gas refrigerant discharged from the compressor 1 flows into the water-refrigerant heat exchanger 2, dissipates heat to the water flowing through the water pipe 3, performs heat exchange, and condenses. At this time, the hot gas valve 9 for defrosting operation is closed. The condensed liquid refrigerant is decompressed by the electric expansion valve 4 to become a low-pressure two-phase refrigerant, and is passed through the opened liquid on-off valves 5a, 5b and 5c to the air heat exchanger dividing sections 6a, 6b and 6c. Inflow. Here, the low-pressure two-phase refrigerant absorbs heat from the outside air sent by the blower 7 and evaporates to become a gas refrigerant. This gas refrigerant is temporarily accumulated in the accumulator 8 and is sucked into the compressor 1 again. Thereafter, this operation is repeated.

(Defrosting operation of refrigeration cycle equipment)
FIG. 3 is a flowchart showing the operation of the defrosting operation of the refrigeration cycle apparatus.
In the refrigeration cycle apparatus according to Embodiment 1 of the present invention, when the water heating operation described above is continued under conditions where the outside air is at a low temperature and the evaporation temperature is below freezing point, frost is generated on the surface of the air heat exchanger 6, and Begin to disturb the heat collection. At this time, for example, when the deviation between the temperature detected by the outside air temperature sensor 14 and the temperature detected by the low-pressure refrigerant temperature sensor 13 is larger than a predetermined value, it is determined that there is an electric heat failure due to frost formation and the defrosting operation is started. (Step S1). Note that the start conditions for the defrosting operation are not limited to those described above. For example, frost formation occurs when a predetermined time (for example, 60 minutes) has passed when the temperature detected by the low-pressure refrigerant temperature sensor 13 is below freezing. You may judge that you are doing. When the defrosting operation is started, first, the blower 7 is stopped, the hot gas valve 9 is opened, and then the electric expansion valve 4 is closed or slightly opened so that heat exchange is performed in the water-refrigerant heat exchanger 2. Is not performed (step S2). Subsequently, the liquid on / off valves 5b and 5c are closed while the liquid on / off valve 5a is opened (step S3). As a result, the high-temperature gas refrigerant discharged from the compressor 1, that is, hot gas, flows only to the air heat exchanger dividing unit 6a via the hot gas valve 9 and the liquid on-off valve 5a. At this time, the air heat exchanger divider 6a becomes hot due to the hot gas discharged from the compressor 1 and melts frost, and in the internal refrigerant flow path, the liquid refrigerant accumulates by condensing immediately after the start of defrosting. Thereafter, the refrigerant state of the internal refrigerant flow path of the air heat exchanger dividing unit 6a shifts to a high dryness state while gradually increasing the pressure as the frost melts. And the defrosting operation | movement in the air heat exchanger division | segmentation part 6a is complete | finished because detection temperature T1 of the temperature sensor 11a has reached the preset temperature (for example, 7 degreeC) which can be judged that the frost has fully melt | dissolved (step S4).

  Next, the liquid on-off valve 5b is opened to start the defrosting operation in the air heat exchanger dividing unit 6b (step S5). At this time, the liquid on-off valve 5a installed on the refrigerant circuit on the inflow side of the air heat exchanger divider 6a that has already been defrosted is kept open. In the air heat exchanger dividing unit 6b that is in a frosted state, hot gas discharged from the compressor 1 flows in and frost is melted, and in the internal refrigerant flow path, the liquid refrigerant is condensed immediately after the start of defrosting. In the air heat exchanger dividing unit 6a, which is already hot, the gas refrigerant is circulated as it is, so that the gas refrigerant is supplied to the suction side of the compressor 1, and the pressure and temperature can be maintained high. Thereby, since the pressure and temperature of the refrigerant discharged from the compressor 1 are also maintained in a high state, it can contribute to the defrosting operation in the air heat exchanger dividing unit 6b. Thereafter, the refrigerant state of the internal refrigerant flow path of the air heat exchanger dividing unit 6b shifts to a high dryness state while gradually increasing the pressure as the frost melts. And the defrosting operation | movement in the air heat exchanger division | segmentation part 6b is complete | finished because the detection temperature T2 of the temperature sensor 11b has reached the preset temperature (for example, 7 degreeC) which can be judged that the frost has fully melt | dissolved (step S6).

  Next, the liquid on-off valve 5c is opened to start the defrosting operation in the air heat exchanger dividing unit 6c (step S7). At this time, the liquid on-off valves 5a and 5b installed on the refrigerant circuit on the inflow side of the air heat exchanger dividers 6a and 6b that have already been defrosted are kept open. The operation at this time is the same as step S5 described above. And the defrosting operation | movement in the air heat exchanger division | segmentation part 6c is complete | finished because detection temperature T3 of the temperature sensor 11c has reached the preset temperature (for example, 7 degreeC) which can be judged that the frost has fully thawed, and all defrosting It determines with operation | movement being complete | finished and complete | finishes a defrost operation (step S8). After the defrosting operation is finished, the blower 7 is operated, the electric expansion valve 4 is opened, and the hot gas valve 9 is closed, so that the water-refrigerant heat exchanger 2 is again the condenser and the air heat exchanger. A water heating operation is performed using 6 as an evaporator for collecting heat from the outside air (step S9).

  Here, the amount of refrigerant enclosed in the refrigeration cycle apparatus according to Embodiment 1 of the present invention will be described. The amount of refrigerant enclosed in the refrigeration cycle apparatus according to Embodiment 1 of the present invention is equal to the amount of refrigerant required for the water heating operation. That is, the required amount of refrigerant in a state where the water-refrigerant heat exchanger 2 functions as a condenser and the air heat exchanger 6 functions as an evaporator is the enclosed refrigerant amount. On the other hand, during the defrosting operation, there is no liquid refrigerant in the water-refrigerant heat exchanger 2, and there is no liquid refrigerant in the air heat exchanger division where no hot gas is circulated. Therefore, the operation state in which the refrigerant is most necessary during the defrosting operation is the timing at which the refrigerant is temporarily accumulated in the defrosting air heat exchanger division, and the air heat exchanger division at that time is almost liquid refrigerant. It is a state that is satisfied with. At this time, the volume of the refrigerant flow path in each of the air heat exchanger dividing sections 6a, 6b and 6c is substantially the same as or smaller than the volume of the refrigerant flow path of the water-refrigerant heat exchanger 2, -If the refrigerant heat exchanger 2 is filled with sufficient refrigerant to function as a condenser, one of the air heat exchanger dividers 6a, 6b and 6c is filled with liquid refrigerant during the defrosting operation. Even if it does, it will not become a refrigerant shortage state. Accordingly, since there is no difference in the amount of enclosed refrigerant required between the water heating operation and the defrosting operation, the accumulator 8 may be considerably small or unnecessary.

(Effect of Embodiment 1)
As in the above-described configuration and operation, the refrigerant flow volume in each of the air heat exchanger dividers 6a, 6b, and 6c is substantially the same as or smaller than the refrigerant flow volume in the water-refrigerant heat exchanger 2. Therefore, as long as the refrigerant sufficient for the water-refrigerant heat exchanger 2 to function as a condenser is sealed, one of the air heat exchanger dividing parts 6a, 6b, and 6c during the defrosting operation. Even if one of them is filled with liquid refrigerant, the refrigerant does not become insufficient, and even when liquid refrigerant accumulates in the defrosting air heat exchanger 6, the refrigerant flowing into the compressor 1 does not flow. There is no shortage of defrosting time.
Moreover, it is sufficient to enclose only the amount of refrigerant necessary for the water heating operation, and it is not necessary to enclose a large amount of refrigerant for the defrosting operation, so that liquid back can be avoided, and surplus refrigerant can be removed. The liquid storage container such as the accumulator 8 installed for storage may be small or unnecessary, so that the cost can be reduced.
Further, the air heat exchanger 6 divided into three parts in the air heat exchanger dividing parts 6a, 6b, and 6c is formed as an integrated type, so that the air heat exchanger is not defrosted by heat conduction between the fins. Since heat is transmitted to the part and frost melts, it is convenient.
Further, the air heat exchanger 6 is divided into three in the vertical direction, and the air defrosting operation is performed from the top, so that the air heat exchange in which the frost melting water above has not yet been defrosted is performed. Since it is dripped at an apparatus division | segmentation part, it can be used effectively, without releasing the heat | fever input for defrosting.

When the outside air temperature is higher than 0 ° C., frost is melted even in the air heat exchanger dividing unit that closes the liquid on-off valve. In this case, the compressor 1 is stopped. The blower 7 may be operated at a low speed to perform defrosting of the air heat exchanger 6 by outside air at 0 ° C. or higher, so-called off-cycle defrosting.
Further, in the defrosting operation shown in FIG. 3, the defrosting operation is performed in the order of the air heat exchanger dividing units 6a, 6b, and 6c, but is not limited to this order, and the defrosting is performed in a different order. The operation may be performed. At this time, liquid on-off valves 5a, 5b and 5c are provided on the refrigerant circuits on the inflow side of the air heat exchanger dividing sections 6a, 6b and 6c, respectively. As shown in FIG. When the defrosting operation is performed from the device dividing unit 6a, the liquid on / off valve 5a is always open in both the water heating operation and the defrosting operation, and therefore the liquid on / off valve 5a may not be installed.
Further, the air heat exchanger 6 in the refrigeration cycle apparatus according to Embodiment 1 is divided into three parts, that is, the air heat exchanger dividing parts 6a, 6b, and 6c. It may be divided or more.

Embodiment 2. FIG.
(Whole water heater configuration)
FIG. 4 is a circuit configuration diagram of a water heater according to Embodiment 2 of the present invention.
In FIG. 4, the refrigeration cycle unit 31 is provided with the refrigeration cycle apparatus according to the first embodiment. The water pipe 3 connected to the water-refrigerant heat exchanger 2 in the refrigeration cycle apparatus is separated from the refrigerant circuit in the refrigeration cycle apparatus, and the water-refrigerant heat exchanger 2, the water-refrigerant heat exchange. A water circulation circuit is formed by sequentially connecting a tank 18 for storing water heated by the vessel 2 and a pump 17 for sending out water flowing out of the tank 18. The water storage circuit 32 is constituted by this water circulation circuit.

(Operation of the water heater)
The water flowing through the water circulation circuit is sent to the water-refrigerant heat exchanger 2 by the pump 17, and is warmed by heat radiation from the refrigerant circuit in the water-refrigerant heat exchanger 2. The warmed water flows into the tank 18 and is stored. The water stored in the tank 18 is sent to the pump 17 again.

(Effect of Embodiment 2)
With the above configuration, a water heater having the same effects as those of the first embodiment can be obtained.

1 is a circuit configuration diagram of a refrigeration cycle apparatus according to Embodiment 1 of the present invention. It is a three-dimensional block diagram of the refrigeration cycle apparatus. It is a flowchart showing operation | movement of the defrost driving | operation of the same refrigeration cycle apparatus. It is a circuit block diagram of the water heater based on Embodiment 2 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Compressor, 2 Water-refrigerant heat exchanger, 3 Water piping, 4 Electric expansion valve, 5a-5c Liquid on-off valve, 6 Air heat exchanger, 6a-6c Air heat exchanger division | segmentation part, 7 Blower, 8 Accumulator, 9 Hot gas valve, 11a-11c Temperature sensor, 13 Low-pressure refrigerant temperature sensor, 14 Outside air temperature sensor, 17 Pump, 18 Tank, 31 Refrigerating cycle part, 32 Heat storage circuit part.

Claims (8)

A refrigerant circuit that forms a closed circuit by sequentially connecting a compressor, a water-refrigerant heat exchanger, a decompression means, and an air heat exchanger with refrigerant piping;
A hot gas bypass formed by connecting the compressor and the water-refrigerant heat exchanger, and between the pressure reducing means and the air heat exchanger via a first opening / closing means; ,
With
The air heat exchanger has an internal refrigerant flow path divided into two or more systems,
The refrigeration cycle apparatus characterized in that at least one of the divided refrigerant flow paths has a second opening / closing means independently on each refrigerant flow path. The refrigeration cycle apparatus according to claim 1, wherein the divided refrigerant flow path divided into two or more systems has the second opening / closing means independently on each refrigerant path. The refrigeration cycle apparatus according to claim 1 or 2, wherein the air heat exchanger is integrally formed. The refrigeration cycle apparatus according to any one of claims 1 to 3, wherein the two or more refrigerant flow paths in the air heat exchanger are divided in a vertical direction. The internal volume of one of the divided refrigerant flow paths in the air heat exchanger is substantially the same as or smaller than the internal volume of the refrigerant flow path of the water-refrigerant heat exchanger. The refrigeration cycle apparatus according to claim 4. 6. The refrigeration cycle apparatus according to claim 5, wherein an amount of refrigerant enclosed in the refrigerant circuit is substantially the same as or smaller than an amount in which a refrigerant-side flow path of the water-refrigerant heat exchanger is filled with liquid refrigerant. . Having a defrosting operation mode for performing defrosting in the air heat exchanger;
In the defrosting operation mode,
Opening the first opening and closing means, circulating hot gas discharged from the compressor to the air heat exchanger,
The refrigeration cycle apparatus according to any one of claims 1 to 6, wherein the second opening / closing means is sequentially opened to perform defrosting for each of the divided refrigerant flow paths. A water heater comprising the refrigeration cycle apparatus according to any one of claims 1 to 7.

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