JP2008224064A - Heat pump hot water supply device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hot water supply system for a heat pump hot water supply device capable of supplying hot water with small power consumption while improving a system performance coefficient during hot water supply and heating operation. <P>SOLUTION: The heat transfer area of a refrigerant-to-refrigerant heat exchange part of a liquid gas heat exchanger is optimized to make a refrigerant circulation amount and the operating pressure of a gas cooler adequate to a refrigerant-to-refrigerant heat exchange amount. This maximizes the system result coefficient for the heat pump hot water supply device, resulting in the highly efficient hot water supply system. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a heat pump hot water supply apparatus that supplies hot water using heat released from a refrigerant in a gas cooler.

  Conventionally, this type of heat pump hot water supply apparatus has a structure as shown in FIG.

  Hereinafter, as a heat pump hot water supply apparatus that uses a substance that can be supercritical on the high pressure side as a refrigerant, a heat pump hot water supply apparatus that uses carbon dioxide as the most common refrigerant at present will be described.

  As shown in FIG. 8, in a conventional heat pump hot water supply apparatus, a refrigerant circuit configured by connecting a heat pump unit 41 to a compressor 31, a gas cooler 32, an expansion valve 33 as a pressure reducing mechanism, and an evaporator 34 in this order in an annular shape. 35 is provided.

  The hot water storage unit 42 is provided with a hot water storage tank 37, a stacking pump 38, a three-way valve 39, and a hot water mixing valve 40, and the top of the hot water storage tank 37 passes through the stacking pump 38, the gas cooler 32, and the three-way valve 39 from the bottom of the hot water storage tank 37. The hot water mixing valve 40 is provided in the mixing portion of the hot water supply pipe from the hot water storage tank 37 and the hot water supply tank 37.

  The refrigerant circuit 35 of the heat pump unit 41 is a liquid gas that performs heat exchange between refrigerants between the high-pressure side refrigerant supplied from the gas cooler 32 to the expansion valve 33 and the low-pressure side refrigerant supplied from the evaporator 34 to the compressor 31. A heat exchanger 36 is provided.

  Further, the liquid gas heat exchanger 36 is configured as shown in FIG.

  As shown in the figure, the liquid gas heat exchanger 36 has a low-pressure refrigerant pipe 44 having a large diameter and a high-pressure refrigerant pipe 43 having a smaller diameter than the low-pressure refrigerant pipe 44 formed inside the low-pressure refrigerant pipe 44. A double pipe structure is provided, and branch pipes 45 are formed at both ends of the high-pressure side refrigerant pipe 43.

  The low pressure side refrigerant pipe 44 and the high pressure side refrigerant pipe 43 form a high pressure side refrigerant flow path 46 and a low pressure side refrigerant flow path 47.

  About the heat pump hot-water supply apparatus comprised as mentioned above, the operation | movement is demonstrated below.

  The high-pressure refrigerant discharged from the compressor 31 is supplied to the gas cooler 32, and heat exchange with water is performed using the heat of condensation in the gas cooler 32. It is supplied to the flow path 46. In the liquid gas heat exchanger 36, heat is exchanged with the refrigerant flowing through the low-pressure side refrigerant flow path 47, and after being dissipated, the heat is supplied to the expansion valve 33. After being depressurized by the expansion valve 33, it is supplied to the evaporator 34 to absorb heat, and is sucked into the compressor 31 through the low-pressure side refrigerant flow path 47 of the liquid gas heat exchanger 36.

  On the other hand, the water heated in the gas cooler 32 is supplied from the bottom of the hot water storage tank 37 by the action of the stacking pump 38, heated in the gas cooler 32, converted into hot water, and returned to the upper part of the hot water storage tank 37 through the three-way valve 39. It is.

  By the way, the liquid gas heat exchanger 36 functions to suppress the high-pressure side refrigerant pressure by exchanging heat between the high-pressure side refrigerant and the low-pressure side refrigerant, but at the same time, raises the refrigerant temperature at the inlet of the gas cooler 32. It also has the function of reducing the amount of refrigerant circulating in the refrigeration cycle.

  Here, an increase in the refrigerant temperature at the inlet of the gas cooler 32 has an effect of increasing the heating capacity, but a decrease in the circulation amount of the refrigerant has an effect of decreasing the heating capacity, and each has an opposite effect. Therefore, the increase / decrease in heating capacity is determined by the contributions of both, and the increase / decrease in system performance coefficient is determined.

Therefore, inventing the liquid gas heat exchanger 36 that maximizes the system coefficient of performance by optimizing the amount of heat exchange between refrigerants in the liquid gas heat exchanger 36 has been very important (for example, Patent Documents). 1 and 2).
JP 2006-300487 A JP 2005-351537 A

  However, although Patent Document 1 describes a summary as a liquid gas heat exchanger with little heat dissipation loss and high heat exchange efficiency, it is a specification that maximizes the system coefficient of performance by paying attention to the amount of heat exchange between refrigerants. There is no mention of. For this reason, the refrigerant temperature at the inlet of the gas cooler is insufficient, or the refrigerant circulation amount becomes excessively low, resulting in a problem that the system performance coefficient is lowered.

  Also, a refrigeration cycle apparatus (not shown) that can adjust the amount of heat exchange between refrigerants in a liquid gas heat exchanger as described in Patent Document 2 has been proposed. Two expansion valves for reducing the pressure are mounted, and it is inevitable that the refrigeration cycle apparatus is enlarged and the control specifications are complicated. Considering that compact heat pump water heaters in recent years are the mainstream, increasing the size of the housing accompanying the expansion of the refrigeration cycle apparatus has been a major issue.

  The present invention solves the above problems and provides a heat pump hot water supply apparatus equipped with a small liquid gas heat exchanger cycle that has the effect of improving the system coefficient of performance and can be stored in a small casing. For the purpose.

In order to achieve the above object, according to the present invention, a liquid gas heat exchanger mounted in a heat pump hot water supply apparatus is a liquid gas heat exchanger having an area of a heat exchange section between refrigerants of 220 cm ² or more and 300 cm ² or less.

According to the present invention, the area of the heat exchanger between the refrigerants of the liquid gas heat exchanger is configured to be not less than 220 cm ^{2 and not} more than 300 cm ^2, thereby obtaining an appropriate amount of heat exchange between the refrigerants and improving the system performance coefficient. An effect can be obtained.

In the embodiment of the present invention, at least a compressor, a gas cooler, a decompression mechanism, an evaporator, and liquid gas heat that performs heat exchange between refrigerants using a high-pressure side refrigerant as a heating fluid and a low-pressure side refrigerant as a heat-receiving fluid. In a heat pump hot water supply apparatus provided with an exchanger, the liquid gas heat exchanger has a heat transfer area of a heat exchange section between refrigerants of 220 cm ² or more and 300 cm ² or less.

  With this configuration, there is an effect that an appropriate amount of heat exchange between refrigerants can be obtained and the system performance coefficient is improved.

  In addition, the present invention is such that the length of the heat exchanger between the refrigerants of the liquid gas heat exchanger is 0.8 m or less, and with this configuration, the present invention is a heat pump for downsizing and storing the liquid gas heat exchanger The unit housing can be made compact.

  In the present invention, the liquid gas heat exchanger has a double pipe structure, and a plurality of inner pipes are arranged inside the outer pipe. With this configuration, the present invention can further reduce the size of the liquid gas heat exchanger and further reduce the size of the housing of the heat pump unit to be stored.

  In the present invention, the liquid gas heat exchanger having a double-pipe structure has an inner pipe as a high-pressure side refrigerant pipe and an outer pipe as a low-pressure side refrigerant pipe. With this configuration, the present invention can reduce the thickness of the outer tube, and can reduce the amount of material used for the liquid gas heat exchanger.

  Further, the present invention is a liquid gas heat exchanger having a double pipe structure, wherein the inner tube has two φ4 mm copper tubes and the outer tube has one φ13 mm copper tube, and the length of the heat exchanger between the refrigerants is long. The thickness is 0.4 m or more and 0.8 m or less. With this configuration, the present invention can minimize the number of branch pipes and reduce the number of manufacturing steps.

  Furthermore, the present invention is a liquid gas heat exchanger having a structure in which a high-pressure side refrigerant pipe and a low-pressure side refrigerant pipe are in contact with each other. With this configuration, the present invention can further reduce the size of the liquid gas heat exchanger and further reduce the size of the housing of the heat pump unit to be stored.

  Further, the present invention is a liquid gas heat exchanger arranged such that a high-pressure side refrigerant pipe and a low-pressure side refrigerant pipe are in contact with each other, and at least one of the high-pressure side refrigerant pipe and the low-pressure side refrigerant pipe is constituted by a plurality. is there. By this structure, this invention can reduce the pressure loss of the refrigerant | coolant piping of a liquid gas heat exchanger.

  Further, the present invention provides a structure in which a plurality of refrigerant pipes are wound around the other refrigerant pipe in a liquid gas heat exchanger in which at least one of the high-pressure side refrigerant pipe and the low-pressure side refrigerant pipe is constituted by a plurality. It is a thing. With this configuration, the present invention can further reduce the size of the liquid gas heat exchanger and further reduce the size of the housing of the heat pump unit to be stored.

  Further, the present invention is a liquid gas heat exchanger having a structure used for heat exchange between a high-pressure side refrigerant supplied from a gas cooler to a decompression mechanism and a low-pressure side refrigerant supplied from an evaporator to a compressor. . With this configuration, the present invention can effectively operate both the gas cooler and the evaporator.

  In the present invention, a refrigerant that can be in a supercritical state on the high-pressure side is used as the refrigerant. By this structure, this invention can make high pressure side refrigerant | coolant temperature high, and can obtain high temperature hot water efficiently.

  In the present invention, carbon dioxide is used as a refrigerant that can be in a supercritical state on the high-pressure side. With this configuration, since the refrigerant used in the present invention is a non-flammable refrigerant, the risk of ignition or explosion can be eliminated.

Hereinafter, the heat pump hot-water supply apparatus in the Example of this invention is described, referring drawings.
(Example 1)
First, the structure of the liquid gas heat exchanger mounted in the heat pump hot-water supply apparatus in Example 1 of this invention is described.

  FIG. 1 is a cross-sectional view of the liquid gas heat exchanger in the axial vertical direction.

  As shown in FIG. 1, a plurality of high-pressure side refrigerant pipes 1 are arranged in a low-pressure side refrigerant pipe 2. Here, the high-pressure side refrigerant pipe 1 is φ4 mm, and the low-pressure side refrigerant pipe 2 is φ12.7 mm.

  The internal space of the high pressure side refrigerant pipe 1 is a high pressure side refrigerant flow path 3, and the gap between the high pressure side refrigerant pipe 1 and the low pressure side refrigerant pipe 2 is a low pressure side refrigerant flow path 4.

  FIG. 2 is a front view of the liquid gas heat exchanger.

  As shown in FIG. 2, the high-pressure side refrigerant pipe 1 and the low-pressure side refrigerant pipe 2 are branched by branch pipes 5 and 6. Here, the double tube portion has a total length of 0.7 m.

  Next, the operation and action that the liquid gas heat exchanger configured as described above gives to the refrigeration cycle will be described.

  The high-pressure side refrigerant circulating in the high-pressure side refrigerant flow path 3 and the low-pressure side refrigerant circulating in the low-pressure side refrigerant flow path 4 form a counterflow in the liquid gas heat exchanger and exchange heat between refrigerants via the high-pressure side refrigerant pipe 1. I do. Here, inter-refrigerant heat exchange is heat exchange in which the high-pressure side refrigerant is the heating fluid and the low-pressure side refrigerant is the heat receiving fluid.

  The liquid-gas heat exchanger according to the present embodiment is a conventional liquid-gas heat exchanger under rated conditions in which water at 17 ° C. is heated to 65 ° C. hot water by a gas cooler at an intermediate environmental temperature of dry bulb temperature 16 ° C. and wet bulb temperature 12 ° C. Since the heat transfer area is larger than that of the exchanger, the amount of heat exchange between refrigerants also increases.

Thus, as a matter of course, as shown in FIG. 3, the amount of heat exchange between refrigerants increases as the heat transfer area of the liquid gas heat exchanger increases. In addition, the heat transfer area of the liquid gas heat exchanger in a present Example is 150 cm < ² >.

  Next, FIG. 4 shows a Mollier diagram depicting operating points of a refrigeration cycle not equipped with a liquid gas heat exchanger and a refrigeration cycle in the present embodiment. However, the compressor frequency shall be the same.

  When comparing the two refrigeration cycles in FIG. 4, in the refrigeration cycle in the present embodiment equipped with the liquid gas heat exchanger, the compressor suction superheat degree of the refrigerant increases and the refrigerant density decreases. It can be seen that, although the refrigerant circulation amount decreases, the compressor discharge refrigerant temperature rises and the gas cooler is operated in a state where the specific enthalpy difference of the refrigerant in the gas cooler is enlarged.

  At this time, the specific enthalpy of the refrigerant at the gas cooler inlet increases and the refrigerant temperature increases, so that the operating pressure of the gas cooler can be lowered as shown in FIG.

According to the present embodiment, with the above configuration, the liquid gas heat exchanger transfers a predetermined amount of heat between the refrigerants in the liquid gas heat exchanger by setting the heat transfer area of the heat exchanger between the refrigerants to 150 cm ^2. The system performance coefficient improvement effect due to the refrigerant discharge refrigerant temperature can be greatly suppressed, while the system performance coefficient decrease effect due to the decrease in the refrigerant circulation amount can be minimized and the system performance coefficient improvement effect can be maximized. There is an effect.

  Here, the relationship between the amount of heat exchange between refrigerants and the system coefficient of performance is shown in FIG.

  From FIG. 5, when the heat exchange amount between refrigerants is less than or equal to a predetermined amount, the system performance coefficient improves as the heat exchange amount increases, but when the heat exchange amount is greater than or equal to the predetermined amount, the system performance coefficient decreases. I can see the trend.

  This tendency is greatly affected by an increase in the temperature of refrigerant discharged from the compressor when the amount of heat exchange between refrigerants is small. However, if the amount of heat exchange between refrigerants exceeds a predetermined amount and the amount of heat exchange between refrigerants is excessive, the refrigerant circulation rate significantly decreases. This is because the system performance coefficient decreases.

  FIG. 6 shows the relationship between the heat transfer area of the liquid gas heat exchanger and the system performance coefficient.

As shown in the figure, when the heat transfer area is not less than 220 cm ^{2 and not} more than 300 cm ² , the system gas performance coefficient can be maximized by exchanging an appropriate amount of heat between the refrigerants in the liquid gas heat exchanger.

  Here, as an example of the test conditions, the rated conditions of boiling water at 17 ° C. to 65 ° C. with a gas cooler at an intermediate environmental temperature of dry bulb temperature 16 ° C. and wet bulb temperature 12 ° C. are shown. The same effect of improving the system performance coefficient can be obtained at any outdoor temperature.

In addition, although the case where the condenser of the refrigeration cycle apparatus is a CO ₂ heat pump hot water supply apparatus in which the condenser is a gas cooler has been described, the same effect can be obtained even if the condenser is a condenser of an air conditioner.
(Example 2)
Below, the structure of the liquid gas heat exchanger mounted in the heat pump hot-water supply apparatus in Example 2 of this invention is described.

  FIG. 7 is a schematic view of the inter-refrigerant heat exchange section of the liquid gas heat exchanger.

  As shown in the figure, the two high-pressure refrigerant pipes 7 are wound so as to be in contact with the low-pressure refrigerant pipe 8, and branch pipes 9 are arranged at both ends of the high-pressure refrigerant pipe 7.

According to the present embodiment, the above structure improves the system performance coefficient under rated conditions and secures a large heating capacity at an ultra-low ambient temperature and a high incoming water temperature. In addition, since operation | movement and an effect | action are the same as (Example 1), it abbreviate | omitted here.

  In addition, here, the liquid gas heat exchanger in which the two high-pressure refrigerant pipes 7 are wound around the low-pressure refrigerant pipe 8 is shown, but a plurality of low-pressure refrigerant pipes 8 are wound around the high-pressure refrigerant pipe 7. A liquid gas heat exchanger that is in contact with each other or a liquid gas heat exchanger that is in contact with a plurality of high pressure side refrigerant pipes and low pressure side refrigerant pipes that are wound around each other can be manufactured in the same manner, and the same effect can be obtained. Can do.

  The heat pump water heater of the present invention is approximately the same size as an existing liquid gas heat exchanger, has the effect of improving the system performance coefficient, and is useful for improving the efficiency and energy saving of heat pump water heaters in general. is there.

Axial vertical direction sectional view of a liquid gas heat exchanger of a heat pump water heater in Example 1 of the present invention. Front view of liquid gas heat exchanger of the same heat pump water heater The characteristic figure which shows the relationship between the heat transfer area of the heat exchange part between refrigerants of the liquid gas heat exchanger of the heat pump water heater, and the amount of heat exchange Mollier wire depicting the operating line of the refrigeration cycle under the rated conditions of boiling 17 ° C water to 65 ° C hot water with a gas cooler at an intermediate environmental temperature of 16 ° C dry bulb temperature and 12 ° C wet bulb temperature in the same heat pump water heater Figure Characteristic diagram showing the relationship between the amount of heat exchange between refrigerants and the system coefficient of performance in a liquid gas heat exchanger under rated conditions in the same heat pump water heater The characteristic figure which shows the relationship between the heat transfer area of the heat exchange part between refrigerants of the liquid gas heat exchanger in the rated condition in the heat pump water heater and the system performance coefficient The schematic diagram of the heat exchanger between refrigerant | coolants of the liquid gas heat exchanger of the heat pump water heater in Example 2 of this invention. Schematic diagram showing a conventional refrigeration cycle apparatus Schematic diagram showing a conventional liquid gas heat exchanger

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 High pressure side refrigerant pipe 2 Low pressure side refrigerant pipe 3 High pressure side refrigerant flow path 4 Low pressure side refrigerant flow path 5 Branch pipe 6 Branch pipe 7 High pressure side refrigerant pipe 8 Low pressure side refrigerant pipe 9 Branch pipe 31 Compressor 32 Gas cooler 33 Expansion valve 34 Evaporator 35 Refrigerant circuit 36 Liquid gas heat exchanger 37 Hot water storage tank 38 Laminated pump 39 Three-way valve 40 Hot water supply mixing valve 41 Heat pump unit 42 Hot water storage unit 43 High pressure side refrigerant pipe 44 Low pressure side refrigerant pipe 45 Branch pipe 46 High pressure side refrigerant flow path 47 Low pressure side refrigerant flow path

Claims (11)

At least a compressor, a gas cooler, a decompression mechanism, an evaporator, and a liquid gas heat exchanger that performs heat exchange between refrigerants using a high pressure side refrigerant as a heat transfer fluid and a low pressure side refrigerant as a heat reception fluid. A heat pump hot water supply apparatus characterized in that the heat exchanger area of the heat exchanger between the refrigerants is 220 cm ² or more and 300 cm ² or less. 2. The heat pump hot water supply apparatus according to claim 1, wherein the liquid-gas heat exchanger has a length of a heat exchanger between refrigerants of 0.8 m or less. The heat pump hot water supply apparatus according to claim 2, wherein the liquid gas heat exchanger is formed by a double pipe structure, and a plurality of inner pipes are arranged inside the outer pipe. 4. The heat pump hot water supply apparatus according to claim 3, wherein the liquid gas heat exchanger uses the inner pipe as a high-pressure side refrigerant pipe and the outer pipe as a low-pressure side refrigerant pipe. The liquid gas heat exchanger is configured such that the inner pipe is composed of two copper pipes of about 4 mm and the outer pipe is composed of one copper pipe of about 13 mm, and the length of the heat exchanger between the refrigerants is 0.4 m or more. It is 0.8 m or less, The heat pump hot-water supply apparatus of Claim 4 characterized by the above-mentioned. The heat pump water heater according to claim 2, wherein the liquid gas heat exchanger is arranged so that the high-pressure side refrigerant pipe and the low-pressure side refrigerant pipe are in contact with each other. The heat pump hot water supply apparatus according to claim 6, wherein the liquid gas heat exchanger includes a plurality of at least one of the high-pressure side refrigerant pipe and the low-pressure side refrigerant pipe. The heat pump water heater according to claim 7, wherein the liquid gas heat exchanger winds a plurality of refrigerant pipes around the other refrigerant pipe. The liquid-gas heat exchanger is used for heat exchange between a high-pressure refrigerant supplied from the gas cooler to the decompression mechanism and a low-pressure refrigerant supplied from the evaporator to the compressor. The heat pump hot water supply apparatus according to 5 or 8. The heat pump hot water supply apparatus according to claim 9, wherein a refrigerant that can be in a supercritical state on the high-pressure side is used as the refrigerant. The heat pump hot water supply apparatus according to claim 10, wherein carbon dioxide is used as the refrigerant.

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