JP4396569B2 - Refrigeration cycle and heat pump water heater using the same - Google Patents

Description

  The present invention relates to an improvement in the performance of a refrigeration cycle used in a heat pump hot water supply apparatus or the like.

Conventionally, when a heat pump type hot water supply apparatus is operated, frost adheres to the evaporator, and the efficiency of heat exchange in the evaporator may decrease. On the other hand, the defrosting means of an evaporator is developed for the purpose of removing the frost of an evaporator (for example, refer patent document 1). FIG. 5 is a configuration diagram of a heat pump type hot water supply apparatus using a conventional refrigeration cycle. Hereinafter, a heat pump type hot water supply apparatus using a conventional refrigeration cycle will be described with reference to FIG.

  5 includes a compressor 101 that compresses a refrigerant, an evaporator 102 that performs heat exchange between the refrigerant and the outside air, a decompression device 103 that decompresses the refrigerant, and a radiator 104 that performs heat exchange between the refrigerant and water. The four-way valve 105 for switching the refrigerant circulation path is connected to the refrigeration cycle unit connected through the refrigerant pipe 106 as shown in FIG. 5, and the hot water storage tank 107 for storing hot water and the hot water storage tank 107 are supplied with water. A hot water supply port 108, a hot water outlet 109 for extracting hot water from the hot water storage tank 107, and a pump 110 for adjusting the flow rate of the water are configured as a hot water supply unit connected as shown in FIG.

  Next, the operation of a heat pump hot water supply apparatus using a conventional refrigeration cycle will be described. A heat pump type hot water supply apparatus using a conventional refrigeration cycle compresses a refrigerant by a compressor 101, is led to a radiator 104 through a circuit indicated by a solid line arrow of a four-way valve 105, and converts the refrigerant in a high-temperature gaseous state. By using the radiator 104, the water and the refrigerant exchange heat to convert the water into hot water. However, when a heat pump type hot water supply apparatus is used, frost adheres to the evaporator 102, and the efficiency of heat exchange between the refrigerant and the outside air may decrease.

Therefore, when frost is generated in the evaporator 102, heating to water is stopped, and the circuit of the four-way valve is switched so that the refrigerant passes through the circuit indicated by the dotted arrow of the four-way valve 105. As a result, the high-temperature refrigerant compressed by the compressor 101 is supplied to the condenser 102, and frost can be removed by the refrigerant.
Japanese Patent Laid-Open No. 11-193958

  However, in the above-described conventional refrigeration cycle, when frost is generated in the evaporator 102, the heating is stopped and the operation for removing the frost is performed. Had the problem of being unable to supply.

  This invention solves the said subject, and it aims at providing the refrigeration cycle with high usability which enables a continuous operation even if frost adheres to an evaporator.

In order to solve the conventional problems, a refrigeration cycle according to the present invention includes a compressor that compresses a refrigerant, a radiator that radiates heat from the compressed refrigerant, a decompression device that decompresses refrigerant downstream of the radiator, and refrigerant and air. A refrigerant circuit that sequentially connects evaporators that exchange heat with each other, compressor frequency control means that changes the operating frequency of the compressor, air temperature detection means that detects the temperature of air supplied to the evaporator, Refrigerant temperature detection means for detecting the temperature of the refrigerant in the flow path from the downstream side of the decompression device to the suction of the compressor, and calculating in advance an air temperature Tg at which the refrigerant temperature Ts becomes 0 ° C. or higher. Even if the temperature detected by the air temperature detecting means is equal to or higher than a pre-calculated air temperature Tg at which the refrigerant temperature Ts is 0 ° C. or higher, the refrigerant temperature Ts detected by the refrigerant temperature detecting means is less than 0 ° C. in case of, before It is to increase the operating frequency of the compressor.

Thus, by the air temperature detecting means and the coolant temperature detecting means each temperature result detected by, by operation to increase the operation frequency of the compressor, compensate a reduction in the heating capacity of the heat pump type hot water supply device In addition, it is possible to prevent a shortage of hot water accompanying a decrease in heating capacity.

  In the refrigeration cycle of the present invention, the refrigerant temperature detecting means is attached to a substantially middle point of the refrigerant flow path of the evaporator.

  As a result, the temperature of the refrigerant can be detected with higher accuracy, and the compressor can be prevented from operating at an excessive frequency.

  It is possible to provide a highly usable refrigeration cycle that enables continuous operation even if frost adheres to the evaporator.

1st invention connected in order the compressor which compresses a refrigerant | coolant, the radiator which thermally radiates from the said compressed refrigerant | coolant, the decompression device which decompresses the refrigerant | coolant downstream of the said radiator, and the evaporator which heat-exchanges a refrigerant | coolant and air A refrigerant circuit, compressor frequency control means for changing the operating frequency of the compressor, air temperature detection means for detecting the temperature of air supplied to the evaporator, and suction of the compressor from the downstream side of the decompression device Refrigerant temperature detecting means for detecting the temperature of the refrigerant in the flow path up to, and calculating in advance an air temperature Tg at which the refrigerant temperature Ts is 0 ° C. or higher, and the temperature detected by the air temperature detecting means is Even if the refrigerant temperature Ts is equal to or higher than a previously calculated air temperature Tg at which the refrigerant temperature Ts is 0 ° C. or higher, when the refrigerant temperature Ts detected by the refrigerant temperature detecting means is lower than 0 ° C. , the operating frequency of the compressor is set. by increase, change Was operated compressor frequency compensates for lowering ability of the heat pump type hot water supply apparatus, it is possible to prevent the hot water shortage capacity decrease caused by.

  According to a second aspect of the invention, particularly in the first refrigeration cycle, the refrigerant temperature detecting means is attached to a substantially middle point of the refrigerant flow path of the evaporator, whereby the refrigerant temperature detecting means is connected to the gas-liquid two-phase. Therefore, the pressure can be estimated with higher accuracy, and the compressor can be prevented from operating excessively.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a configuration diagram of a heat pump hot water supply apparatus according to Embodiment 1 of the present invention. The heat pump hot water supply apparatus in the first embodiment exchanges heat between the compressor 1 that compresses the refrigerant, the radiator 2 that radiates heat from the compressed refrigerant, the decompression device 3 that depressurizes the refrigerant downstream of the radiator, and the outside air. A refrigerant circuit including an evaporator 4 and sequentially connected in an annular shape by a refrigerant pipe 5, a hot water storage tank 6 for storing hot water heated by the radiator 2, a water supply port 7 for supplying water to the hot water storage tank 6, hot water storage A hot water outlet 8 for taking out hot water from the tank 6 and a hot water supply unit provided with a water pump 9 for adjusting the flow rate of water supplied from the hot water storage tank 6 to the radiator 2 are configured. An air temperature detecting means 11 for detecting the temperature of the air supplied to the evaporator 4 and a compressor frequency control means 12 capable of changing the operating frequency of the compressor are provided. Further, a refrigerant temperature detecting means 10 is disposed on the refrigerant pipe 5 in the flow path from the downstream side of the decompression device 3 to the suction of the compressor 1.

  The decompression device 3 in the first embodiment refers to a means for reducing the pressure without exchanging heat, and an electronic expansion valve and a capillary tube can be raised. The compressor frequency control means 12 determines the operating frequency of the compressor 1 from the inverter circuit 13 that changes the operating frequency of the compressor 1 and the temperature of the air and the refrigerant, and issues a command to the inverter circuit 13. Consists of.

  About the heat pump type hot-water supply apparatus comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.

  The heat pump type hot water supply apparatus detects the temperature Tg of air supplied to the evaporator 4 by the air temperature detecting means 11 and operates the compressor at a desired operating frequency Fg based on the temperature Tg of the air. The air temperature detection means 11 in Embodiment 1 of this invention means a temperature sensor.

  Here, FIG. 2 is a diagram showing the relationship between the temperature of the air supplied to the evaporator 4 and the temperature of the refrigerant in the evaporator 4 in Embodiment 1 of the present invention. As shown in FIG. 2, when the air temperature Tg is 7 ° C. or higher, Ts is designed to be 0 ° C. or higher. However, the humidity is reduced, or there is an obstruction at the suction port of the evaporator 4, the ventilation is obstructed, or unexpected obstacles such as natural conditions such as headwinds and snowfall occur, and the vapor is supplied to the evaporator 4. Even if the temperature of the air to be secured is sufficiently secured, the refrigerant temperature of the evaporator 4 may be less than 0 ° C. That is, despite the air temperature Tg being 7 ° C., Ts may be less than 0 ° C. and frost may be generated.

  Therefore, next, the refrigerant temperature detection means 10 detects the refrigerant temperature Ts of the evaporator 4. In the first embodiment, the refrigerant temperature detecting means 10 is disposed in the refrigerant flow path near the outlet of the evaporator, and detects the refrigerant temperature Ts. Here, when Tg is 7 ° C. or more and Ts is less than 0 ° C., it is determined that the heating capacity of the heat pump hot water supply device is lowered, and the compressor operating frequency is changed from Fg to α by the compressor frequency control means 12. (In Embodiment 1, it is changed to Fs increased by α = 10 r / sec). In this way, by changing the operating frequency of the compressor 1 from normal Fg to Fs, it is possible to compensate for the insufficient heating capacity due to the reduced capacity, and continue the continuous operation without stopping the heating operation from water to hot water. it can. As a result, it is possible to prevent a shortage of hot water generated due to a decrease in heating capacity.

  In the first embodiment, the temperature of the air supplied to the evaporator 4 is set to 7 ° C. or higher. However, the temperature is not limited to the first embodiment, and a value is set between 0 ° C. and 7 ° C. May be. Further, the value of α in the first embodiment is not limited to 10 r / sec. Moreover, although the refrigerant | coolant temperature detection means 10 is a temperature sensor attached to the copper pipe surface, the same effect can be acquired also in the pressure sensor which directly detects the pressure of a refrigerant | coolant. Even if an accumulator for storing the refrigerant is installed on the suction side of the compressor 1, the same effect can be obtained.

(Embodiment 2)
FIG. 3 is a diagram showing a heat pump hot water supply apparatus according to Embodiment 2 of the present invention. In the heat pump type hot water supply apparatus according to the second embodiment, the refrigerant temperature detecting means 10 of the heat pump type hot water supply apparatus according to the first embodiment is disposed at a substantially middle point of the refrigerant flow path of the evaporator 4. Here, the effect of the second embodiment will be described with reference to FIGS. The same parts as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted, and the configuration and operation thereof are also the same as those in the first embodiment, and thus description thereof is omitted.

  4 (a) and 4 (b) are detailed views of part A of FIG. 3, and FIG. 4 (a) is an explanatory diagram of the refrigerant state of the evaporator according to Embodiment 2 of the present invention (during standard load operation). 4 (b) is a refrigerant state explanatory diagram (during overload operation) of the evaporator according to Embodiment 2 of the present invention. The white arrow in the figure indicates the flow direction of the refrigerant.

In FIG. 3, the high-temperature and high-pressure refrigerant discharged from the compressor 1 is in a gas-liquid two-phase state by the decompressor 3 through the radiator 2. Then, the refrigerant evaporates through the evaporator 4, and after exiting the evaporator 4, becomes a gas phase state and is sucked into the compressor 1. Here, when the pressure and temperature in each part of the refrigerant circuit at the time of operation of the heat pump type hot water supply apparatus are stable, as shown in FIG. 4 (a), the refrigerant is in a gas-liquid two-phase state (B part). When the load on the evaporator 4 side increases, as shown in FIG. 4B, the refrigerant up to the substantially middle point of the refrigerant flow path of the evaporator 4 is in a gas-liquid two-phase state (C Part), from the substantially intermediate point of the refrigerant circuit of the evaporator 4 to the outlet of the evaporator 4 may be in a gas phase (part D). Therefore, if the refrigerant temperature detecting means 10 is provided in the vicinity of the outlet of the evaporator 4 as in the first embodiment, accurate pressure measurement may not be possible because the refrigerant is in the gas phase region, and the excessive heating capacity is compensated. End up.

  Therefore, by providing the refrigerant temperature detecting means 10 at a substantially middle point of the refrigerant flow path of the evaporator 4, it is possible to detect the temperature in the gas-liquid two-phase state and estimate the accurate pressure. As a result, the pressure on the low-pressure side in the compressor 1 can be estimated, so that the capacity reduction of the evaporator 4 can be accurately estimated, and the operation with the excessive heating capacity that may occur in the first embodiment is prevented. Operation with a desired heating capacity is possible. Even if an accumulator for storing the refrigerant is installed on the suction side of the compressor 1, the same effect can be obtained.

  As described above, the refrigeration cycle according to the present invention is generated by various outdoor weather and installation conditions by detecting the temperature of the air and the temperature of the refrigerant and changing the operation frequency of the compressor accordingly. Since the capability reduction of the heat pump type hot water supply apparatus can be compensated, the present invention can be applied not only to the heat pump type hot water supply apparatus but also to an apparatus including a compressor whose capability is reduced due to a temperature decrease of the refrigerant.

  The liquid in the hot water tank 6 can be used not only for hot water supply but also for floor heating and indoor air conditioning. In that case, heat may be radiated by a fan without using a liquid.

The block diagram of the heat pump type hot-water supply apparatus in Embodiment 1 of this invention Correlation diagram between the temperature of air supplied to the evaporator and the temperature of refrigerant in the evaporator in Embodiment 1 of the present invention The block diagram of the heat pump type hot-water supply apparatus in Embodiment 2 of this invention (A) Detailed refrigerant state diagram of evaporator in embodiment 2 of the present invention (during standard load operation) (b) Refrigerant state explanatory diagram of evaporator in embodiment 2 of the present invention (during overload operation) Configuration diagram of a heat pump type hot water supply device using a conventional refrigeration cycle

DESCRIPTION OF SYMBOLS 1 Compressor 2 Radiator 3 Pressure reducing device 4 Evaporator 5 Refrigerant piping 6 Hot water storage tank 7 Water supply port 8 Hot water extraction port 9 Water pump 10 Refrigerant temperature detection means 11 Air temperature detection means 12 Compressor frequency control means 13 Inverter circuit 14 Microcomputer

Claims (3)

A compressor that compresses the refrigerant; a radiator that dissipates heat from the compressed refrigerant; a decompressor that depressurizes the refrigerant downstream of the radiator; a refrigerant circuit that sequentially connects an evaporator that exchanges heat between the refrigerant and air; and the compression Compressor frequency control means for changing the operating frequency of the machine, air temperature detection means for detecting the temperature of the air supplied to the evaporator, and in the flow path from downstream of the decompression device to suction of the compressor A refrigerant temperature detecting means for detecting the temperature of the refrigerant , an air temperature Tg at which the refrigerant temperature Ts is 0 ° C. or higher is calculated in advance, and the temperature detected by the air temperature detecting means is 0 when the refrigerant temperature Ts is 0. The operating frequency of the compressor is increased when the refrigerant temperature Ts detected by the refrigerant temperature detecting means is less than 0 ° C. even when the air temperature is equal to or higher than the air temperature Tg calculated in advance. Frozen cycle . 2. The refrigeration cycle according to claim 1, wherein a refrigerant temperature detecting means is provided at a substantially middle point of the refrigerant flow path of the evaporator. A heat pump type hot water supply apparatus comprising the refrigeration cycle according to claim 1.

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