JP2009133530A - Heat exchanger and heat pump hot water supply machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enlarge the degree of freedom in adjusting a pitch of refrigerant side heat transfer pipes in a water refrigerant heat exchanger. <P>SOLUTION: The water refrigerant heat exchanger 3 includes: a passage member 13 formed cylindrical by spirally winding a member having a U-shaped section; and an inner cylinder 15 and an outer cylinder 17, which are provided in close contact with the outer surface and the inner surface of the cylindrical passage member 13, wherein a water passage 3b having a substantially rectangular section is formed in a space partitioned by the passage member 13, the inner cylinder 15 and the outer cylinder 17, and the heat transfer pipes 19 having a refrigerant passage 3a circular in section are provided at spaces spirally in contact with the outer surface of the outer cylinder 17. A soldered part 21 soldered extending over the full length of the heat transfer pipe 19 is provided in the periphery of a contact part between the outer surface of the outer cylinder 17 and the heat transfer pipe 19. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a heat exchanger, and more particularly to a technique for improving the heat exchange performance of a heat exchanger.

  2. Description of the Related Art Conventionally, in a heat pump type hot water heater, a heat exchanger that heats water with a refrigerant (hereinafter referred to as a water-refrigerant heat exchanger) contacts a water heat transfer tube through which water flows and a cold-side heat transfer tube through which refrigerant flows. It is known that the contact portion between the water heat transfer tube and the refrigerant heat transfer tube is brazed. In particular, taking into account changes in the heat transfer coefficient of the phase-changing refrigerant, heat exchange performance is improved by changing the winding pitch of the refrigerant heat transfer tube with respect to the pipe line between the inlet and outlet sides of the water heat transfer tube It has been proposed (for example, Patent Document 1).

  On the other hand, the plate material is folded at 90 degrees at an appropriate interval, and two plates formed in a zigzag shape are stacked and stored in a box-type container, and the meandering water flows in a vertical direction in the box-type container. There is known a heat exchanger in which a path is formed and three heat transfer tubes through which a refrigerant flows are bundled and wound into a spiral shape around the outer surface of a box-type container (for example, Patent Document 2). ).

JP 2004-278807 A JP 2005-133999 A

  However, since the technology of Patent Document 1 is formed in a cylindrical shape by spirally winding a circular water heat transfer tube, the uneven portion of the water heat transfer tube is formed in the axial direction of the outer surface thereof. When adjusting the helical pitch of the refrigerant heat transfer tube, the degree of freedom of pitch adjustment is small.

  Further, Patent Document 2 does not consider the adjustment of the helical pitch of the heat transfer tube, and the flow path through which water flows is a meandering path, so that the pressure loss increases.

  This invention makes it a subject to enlarge the freedom degree of pitch adjustment according to the phase change of the refrigerant | coolant of the refrigerant | coolant side heat exchanger tube in a water refrigerant | coolant heat exchanger.

  In order to solve the above-described problems, the heat exchanger according to the present invention includes a first heat transfer member through which a first refrigerant that undergoes a gas-liquid phase change is circulated, and a second heat through which a liquid second refrigerant is circulated. In a heat exchanger that includes a heat transfer member and exchanges heat between the first and second heat transfer members, the second heat transfer member is spirally wound so that the rectangular cross-section flow paths are in contact with each other. The first heat transfer member is formed in a cylindrical shape, and the pipes having a circular cross section are spirally wound around at least one of the outer surface and the inner surface of the second heat transfer member with an appropriate space between each other. It is characterized by being formed.

  That is, since the second heat transfer member through which the liquid flows is formed by spirally winding a flow passage having a rectangular cross section, the outer surface and the inner surface of the cylinder of the second heat transfer member are formed flat in the axial direction. In addition, since the circular pipe of the first heat transfer member can be joined to any position in the axial direction of the outer surface or the inner surface of the second flow path member, the helical pitch can be freely adjusted. As a result, the helical pitch of the circular tube of the first heat transfer member can be adjusted in accordance with the thermal resistance value of the phase-changing refrigerant.

  For example, in the pipe line of the first heat transfer member, the thermal resistance value is the lowest near the boundary where the first refrigerant changes from the gas phase state to the liquid phase state, and the first refrigerant enters from the position. Since the thermal resistance value increases toward the outlet side and the outlet side, the pitch of the spiral near the boundary is roughened, and the spiral pitch is increased in stages toward the water inlet side or outlet side from the vicinity of the boundary. Thus, the heat exchange performance can be improved. That is, it is desirable to set the interval between the pipes of the first heat transfer member according to the gas-liquid phase change mode of the first refrigerant flowing in the pipe.

  ADVANTAGE OF THE INVENTION According to this invention, the freedom degree of pitch adjustment can be enlarged according to the phase change of the refrigerant | coolant of the refrigerant | coolant side heat exchanger tube in a water refrigerant | coolant heat exchanger.

  Hereinafter, the present invention will be described based on embodiments.

(Embodiment 1)
FIG. 1 is a schematic diagram of a heat pump water heater according to an embodiment of the present invention, FIG. 2 is a schematic configuration diagram of a heat exchanger of the present embodiment, (a) is a longitudinal sectional view, and (b) is an enlarged view of part A. FIG.

  As shown in FIG. 1, the heat pump water heater of this embodiment includes a compressor 1, a refrigerant flow path 3 a of a water refrigerant heat exchanger 3, an expansion valve 5, and an evaporator 7 via refrigerant pipes. Are sequentially connected, and carbon dioxide, for example, is sealed as a refrigerant. In addition, a water supply pipe 9 supplied from a water supply source such as a water supply (not shown) or a hot water storage tank is connected to the inflow side of the water flow path 3b of the water refrigerant heat exchanger 3, and the outflow side of the water flow path 3b is connected to the outflow side of the water flow path 3b. A hot water supply pipe 11 for supplying hot water to a hot water supply destination such as a hot water storage tank is connected to each other.

  As shown in FIGS. 2A and 2B, the water-refrigerant heat exchanger 3 includes a flow path member 13 formed in a cylindrical shape by spirally winding a member having a U-shaped cross section, and a cylindrical shape. It has the inner cylinder 15 and the outer cylinder 17 which were provided in close contact with the outer surface and inner surface of the formed flow path member 13. The heat transfer member constituted by the flow path member 13, the inner cylinder 15 and the outer cylinder 17 is formed in a cylindrical shape by spirally winding the water flow paths 3b having a rectangular cross section so as to contact each other. On the outer surface of the outer cylinder 17, a heat transfer tube 19 having a refrigerant passage 3 a having a circular cross section is provided in spiral contact with each other at an appropriate interval. Around the contact portion between the outer surface of the outer cylinder 17 and the heat transfer tube 19, a brazing portion 21 that is brazed over the entire length of the heat transfer tube 19 is provided. Further, the water flowing through the water flow path 3b flows spirally from the upper part to the lower part of FIG. 2A, and the refrigerant flowing through the refrigerant flow path 3a flows from the lower part to the upper part, thereby making the refrigerant and water flow counterflow. .

  Next, the helical pitch adjustment of the heat transfer tube 19 will be described with reference to FIGS. FIG. 3 is a graph showing the refrigerant-side heat resistance value and the water-side heat resistance value with respect to the distance from the water inlet when the spirals of the heat transfer tubes 19 of the water-refrigerant heat exchanger are formed at an equal pitch. As shown in FIG. 3, when the heat transfer tubes 19 are spirally wound at an equal pitch, generally, the refrigerant side thermal resistance value (depending on the distance from the water inlet (depending on the phase change mode of the refrigerant flowing through the heat transfer tubes 19) The solid line) and the water-side thermal resistance value (broken line) change. That is, the refrigerant-side thermal resistance value is the lowest in the vicinity of the boundary where the refrigerant changes from the gas phase state to the liquid phase state, and the thermal resistance value increases from the position toward the inlet side and the outlet side of the refrigerant. Further, the water-side thermal resistance value gradually decreases as the distance from the water inlet increases.

  Therefore, in this embodiment, the water-side thermal resistance value is larger than the refrigerant-side thermal resistance value at a distance of about 10% to 50% from the water inlet in FIG. When the distance from the water inlet is about 60% to 100%, the refrigerant-side thermal resistance value is larger than the water-side thermal resistance value, so that the helical pitch of the heat transfer tube 19 is made dense. In this way, the helical pitch of the refrigerant heat transfer tube 5 is adjusted so as to balance the overall thermal resistance values of the refrigerant side and the water side.

  Next, operation | movement of the heat pump water heater of this embodiment is demonstrated using FIG. The high-pressure and high-temperature gas-phase refrigerant compressed by the compressor 1 is sent to the refrigerant flow path 3 a of the water-refrigerant heat exchanger 3. The superheated gas phase refrigerant whose temperature has risen is dissipated and cooled to become a liquid phase refrigerant when heat exchange is performed between the refrigerant flow path 3a and the water flow path 3b in the water refrigerant heat exchanger 3. In this water-refrigerant heat exchanger 3, the water introduced from the water supply pipe 9 is heated by the heat released from the refrigerant, and the heated hot water is supplied to a hot water storage tank or the like via the hot water supply pipe 11.

  The liquid refrigerant whose temperature has been lowered at high pressure is sent from the water refrigerant heat exchanger 3 to the expansion valve 5. In the expansion valve 5, the liquid-phase refrigerant rapidly decreases in pressure and temperature, and becomes a low-pressure and low-temperature gas-phase and liquid-phase refrigerant. The low-pressure and low-temperature gas-phase and liquid-phase refrigerants take heat from the outside in the evaporator 7 and evaporate to become low-pressure and low-temperature gas-phase refrigerants, which are sent to the compressor 1. In this way, the refrigerant repeats a series of cycles, and heats the water by exchanging heat between the heat transfer tube 19 and the heat transfer tube composed of the flow path member 13, the inner cylinder 15 and the outer cylinder 17 in the water refrigerant heat exchanger 3. Like to do.

  In a conventional water-refrigerant heat exchanger (Patent Document 1), when a circular water heat transfer tube is spirally wound and formed into a cylindrical shape, an uneven portion of the water heat transfer tube is formed in the axial direction of the outer surface thereof. Therefore, when trying to join the refrigerant pipe to the outer surface of the water heat transfer pipe formed in a cylindrical shape, the degree of freedom of adjustment of the helical pitch of the refrigerant pipe is small due to the uneven portion on the outer surface. However, according to the present embodiment, the heat transfer member formed by the flow path member 13, the inner cylinder 15 and the outer cylinder 17 is spirally wound so that the water flow paths 3b having a rectangular cross section are in contact with each other, and formed into a cylindrical shape. Therefore, the outer surface of the outer cylinder 17 and the inner surface of the inner cylinder 15 can be formed flat in the axial direction, and the heat transfer member 19 can be arbitrarily connected to the outer surface of the outer cylinder 17 or the inner surface of the inner cylinder 15 in the axial direction. Since it can be joined to the position, the pitch of the spiral can be freely adjusted.

  Further, since the spiral pitch can be freely adjusted, the spiral pitch of the circular tube of the first heat transfer member can be adjusted in accordance with the thermal resistance value of the phase-changing refrigerant. That is, since the thermal resistance value is lowest in the vicinity of the boundary where the refrigerant flowing through the refrigerant flow path 3a changes from the gas phase state to the liquid phase state, the pitch of the spiral of the heat transfer tube 19 near the boundary portion is roughened. The heat exchange performance can be improved by increasing the pitch in steps as it goes from the vicinity toward the water inlet side or the outlet side. That is, the mutual space | interval of the heat exchanger tube 19 can be set according to the aspect of the gas-liquid phase change of the refrigerant | coolant distribute | circulated in a pipe line.

  On the other hand, since the water flow path 3b is formed in a spiral shape, a gentle curve is drawn, so that the water-side pressure loss can be reduced. Moreover, since the flow of water flowing through the refrigerant flow path 3a and the flow of water flowing through the water flow path 3b is an opposite flow advantageous for heat exchange, the heat exchange performance of the water refrigerant heat exchanger 3 can be enhanced.

  Further, since the helical pitch of the heat transfer tube 19 can be freely adjusted, the heat exchange amount between the water heat transfer tube and the refrigerant heat transfer tube at an arbitrary position in the axial direction of the outer surface of the outer tube 17 or the inner surface of the inner tube 15. Can be changed freely. Furthermore, since the outer surface of the outer cylinder 17 or the inner surface of the inner cylinder is flat in the axial direction, the contact area between the heat transfer tube 19 and the outer surface of the outer cylinder 17 or the inner surface of the inner cylinder is made uniform at any position in the axial direction. It is possible to reduce variations in the amount of heat transfer due to the difference in contact area.

  In the above embodiment, the first heat transfer member through which the first refrigerant changing in the gas-liquid phase flows corresponds to the heat transfer tube 19, and the second heat transfer through which the liquid second refrigerant flows. The members correspond to the flow path member 13, the inner cylinder 15, and the outer cylinder 17. Thus, in this embodiment, although what used the flow-path member 13 which formed the U-shaped pipe line in the spiral shape was demonstrated, the 2nd heat-transfer member is not restricted to these forms. . That is, it is only necessary that the rectangular cross-section flow paths are spirally wound so as to be in contact with each other and formed into a cylindrical shape. For example, square pipes can be connected to each other without using the inner cylinder 15 and the outer cylinder 17. The second heat transfer member may be configured by spirally winding so as to be in contact with each other and forming a cylindrical shape.

  Although the heat transfer tube 19 of the present embodiment is provided on the outer surface of the outer cylinder 17, it may be provided on the inner surface of the inner cylinder 15 or both the outer surface of the outer cylinder 17 and the inner surface of the inner cylinder 15 as necessary. In addition, the inner cylinder 15 and the outer cylinder 17 are provided in close contact with the outer surface and the inner surface of the cylindrical flow path member 13, but when there is a possibility that water leaks from the contact portion, the respective contacts are made as necessary. The part may be brazed. In addition, the helical pitch of the heat transfer tubes 19 is not limited to this embodiment, and may be formed at an equal pitch, for example.

  Although the water refrigerant heat exchanger 3 of this embodiment is applied to the heat pump water heater, the range to which the water refrigerant heat exchanger 3 is applied is not limited to the heat pump water heater, and the refrigerant flows through the first heat transfer member. As long as heat exchange is performed between the refrigerant and the refrigerant flowing through the second heat transfer member, it can be used, for example, in an air conditioner.

It is a schematic diagram of the heat pump water heater of one Embodiment of this invention. It is a longitudinal cross-sectional view of the heat exchanger of this embodiment. It is an enlarged surface view of the A section of Fig.2 (a). It is a graph which shows the refrigerant | coolant side thermal resistance value with respect to the distance from a water inlet at the time of forming the spiral of the heat exchanger tube 19 of a water refrigerant | coolant heat exchanger at equal pitch, and a water side thermal resistance value.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Compressor 3 Water refrigerant | coolant heat exchanger 3a Refrigerant flow path 3b Water flow path 5 Expansion valve 7 Evaporator 9 Water supply pipe 11 Hot water supply pipe 13 Flow path member 15 Inner cylinder 17 Outer cylinder 19 Heat transfer pipe 21 Brazing connection part

Claims (5)

A first heat transfer member including a first heat transfer member through which a first refrigerant changing a gas-liquid phase flows, and a second heat transfer member through which a liquid second refrigerant flows. In heat exchangers that exchange heat between
The second heat transfer member is formed in a cylindrical shape by spirally winding the rectangular cross-section flow paths so as to contact each other,
The first heat transfer member is formed by spirally winding pipes having a circular cross section around at least one of an outer surface and an inner surface of a cylinder of the second heat transfer member. Exchanger. The heat exchanger according to claim 1,
The space between the pipes of the first heat transfer member is set according to the gas-liquid phase change mode of the first refrigerant flowing in the pipe. vessel. The heat exchanger according to claim 1 or 2,
The second heat transfer member is provided in close contact with a channel member formed in a cylindrical shape by spirally winding a member having a U-shaped cross section, and an outer surface and an inner surface of the cylindrical channel member. A heat exchanger comprising a cylindrical member. The heat exchanger according to claim 3,
The second heat transfer member is a heat exchanger in which a contact portion between the flow path member and the cylindrical member is brazed.   A heat pump water heater using the heat exchanger according to any one of claims 1 to 4.

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