JP4075732B2 - Heat exchanger for heat pump water heater - Google Patents

Description

  The present invention relates to a heat exchanger for exchanging heat between water and a refrigerant in a heat pump type hot water heater, an air conditioner for home use, and for business use.

For example, heat exchangers for heat exchange between water and refrigerant for heat pump water heaters are designed to meet the market demand for compact water heaters and low prices. There is a further demand for performance, weight reduction, and reduction of peripheral members such as heat insulating materials.
Hereinafter, a conventionally known water heat exchanger for a heat pump type water heater will be described with reference to the drawings.

  In FIG. 14, reference numeral 100 denotes a water heat exchanger main body, in which a refrigerant tube 102 is spirally wound around a core tube 101, and the core tube 101 and the refrigerant tube 102 are joined by brazing. As another example, the refrigerant pipe 102 is wound around the core pipe 101 by connecting a plurality of branch refrigerant pipes (102a, 102b, 102c) to a single flow divider 103 as shown in FIG. .

  As the material of the core tube 101 and the refrigerant tube 102, copper or iron, SUS, brass, aluminum, or the like is used.

  The operation of the heat exchanger configured as described above will be described below.

  First, a refrigerant pipe 102 through which a refrigerant for transferring heat flows is spirally wound around the outer periphery of the core pipe 101 through which water to which warm heat (hereinafter simply referred to as “heat”) flows flows. Heat transfer is performed between both water and refrigerant fluids by using a simple structure that is simply joined.

Therefore, the core tube 101 does not necessarily have to be a straight tube, and the length of the core tube 101 can be designed relatively freely. Thus, heat exchange performance is improved, ease of manufacture, ease of transportation, cost reduction, etc. (For example, refer patent document 1).
JP 2002-228370 A

  However, in the configuration such as the conventional water heat exchanger as described above, the refrigerant tube 102 in which the heat-transmitting refrigerant flows is spirally wound around the outer side of the core tube 101. Heat is partially transmitted to the core tube 101 at a joint portion 104 (not shown) with 101, and heat is released from the non-joint portion to the outside. Therefore, in order to improve the heat exchange performance of the water heat exchanger 100, it is necessary to cover the outside with a member that suppresses heat transfer such as a heat insulating material. Therefore, the water heat exchanger alone can improve the heat exchange performance with a simple structure, and even if it is easy to manufacture, easy to transport, and reduces costs, peripheral members such as heat insulating materials are indispensable. When incorporated in products such as containers, there is a drawback that it is not possible to achieve sufficient compactness, weight reduction, and reduction of peripheral members such as heat insulating materials.

  The present invention solves the above-mentioned problems, and as a heat exchanger alone, heat exchange performance can be improved with a simple structure, and peripheral members such as a heat insulating material can be simplified and incorporated in a product such as a water heater. In particular, the present invention provides a heat exchanger that can be made sufficiently compact, lightweight, and reduce peripheral members such as heat insulating materials.

In order to solve the above problems, a heat exchanger according to the present invention includes a pipe 1 through which water flows and a pipe 2 through which a refrigerant flows inside the pipe 1 in a spiral shape . Is the carbon dioxide, the refrigerant is circulated, the number of the spirally wound tubes 2 is N, and the inner diameter of the tubes 2 is d3. It is for a heat pump type water heater characterized by the relationship of ( Equation 1) between d3, and heat from the refrigerant can be transferred from the entire pipe 2 to the water flowing inside the pipe 1. In addition, the heat insulating material attached to the water heat exchanger can be simplified, and when assembled in a product such as a water heater, it has the effect of being sufficiently compact and lightweight. Further, when the number of the tubes 2 that are circulated through the refrigerant and spirally wound is N and the inner diameter of the tubes 2 is d3, the distance between the number N of the tubes 2 and the inner diameter d3 of the tubes 2 (Equation 1) Therefore, the balance between the heat transfer coefficient in the pipe 2 and the pressure loss is optimized, and the water heat exchanger is reduced in size and weight. Moreover, it has the effect | action of obtaining high heat pump efficiency by using as a water / refrigerant heat exchanger for heat pump water heaters.

  Further, the pipe 1 is formed by spirally winding a plurality of branch pipes branched from a flow divider inside the pipe 1 through which water flows, and by dividing the refrigerant pipe, the refrigerant pipe is spirally formed. An increase in pressure loss of the refrigerant in the refrigerant pipe due to winding can be suppressed, and heat transfer with water is further improved. For this reason, it has the effect | action that the pipe | tube length of the pipe | tube 1 for obtaining required heat exchange capability can be shortened, and more compact and lightweight can be achieved.

According to the heat exchanger of the present invention, the pipe 1 through which water flows and the pipe 2 through which the refrigerant flows inside the pipe 1 are spirally formed and enclosed, and the refrigerant flowing through the pipe 2 is removed by carbon dioxide. When the number of the tubes 2 spirally wound is N and the inner diameter of the tube 2 is d3, the number of the tubes 2 and the inner diameter d3 of the tube 2 (several 1) It is for a heat pump type water heater characterized by having the relationship of 1), and can transfer heat from the refrigerant from the entire pipe 2 to the water flowing in the pipe 1. The heat insulating material attached to the water heater can be simplified, and when it is incorporated into a product such as a water heater, it can be made compact and light. Also, the number of tubes 2 which refrigerant is wound in the distribution and spirally and N, in the case where the inner diameter of the tube 2 and the d3, and the number N of the tube 2, (the number between the inner diameter d3 of the tube 2 1 ), The balance between the heat transfer coefficient in the pipe 2 and the pressure loss can be optimized, and the water heat exchanger can be reduced in size and weight. Moreover, it has the effect | action of obtaining high heat pump efficiency by using as a water / refrigerant heat exchanger for heat pump water heaters.

  Further, the pipe 1 is formed by spirally winding a branch pipe branched into a plurality from the flow divider and enclosing the pipe. By dividing the refrigerant pipe, the refrigerant is obtained by spirally winding the refrigerant pipe. An increase in pressure loss of the refrigerant in the pipe can be suppressed, and heat transfer with water is further improved. For this reason, the tube length of the tube 1 for obtaining a necessary heat exchange capability can be further shortened, and further reduction in size and weight can be achieved.

The invention of the heat exchanger according to claim 1 is characterized in that a pipe 1 through which water flows and a pipe 2 through which a refrigerant flows inside the pipe 1 are spirally formed and contained , and also flows through the pipe 2. When the refrigerant is carbon dioxide, the refrigerant circulates, the number of the spirally wound tubes 2 is N, and the inner diameter of the tube 2 is d3, the distance between the number N of the tubes 2 and the inner diameter d3 of the tube 2 The heat pump type water heater is characterized in that there is a relationship of ( Equation 1), and heat from the refrigerant can be transferred from the entire pipe 2 to the water flowing inside the pipe 1. The heat insulating material attached to the exchanger can also be simplified, and has the effect of being sufficiently compact and lightweight when incorporated in a product such as a water heater. Further, when the number of the tubes 2 that are circulated through the refrigerant and spirally wound is N and the inner diameter of the tubes 2 is d3, the distance between the number N of the tubes 2 and the inner diameter d3 of the tubes 2 (Equation 1) Therefore, the balance between the heat transfer coefficient in the pipe 2 and the pressure loss is optimized, and the water heat exchanger is reduced in size and weight. Moreover, it has the effect | action of obtaining high heat pump efficiency by using as a water / refrigerant heat exchanger for heat pump water heaters.

  The invention according to claim 2 is the invention according to claim 1, wherein the pipe 1 is encased by spirally winding a plurality of branch pipes branched from a flow divider inside the pipe 1 through which water flows. Yes, by dividing the refrigerant pipe, an increase in the pressure loss of the refrigerant in the refrigerant pipe caused by spirally winding the refrigerant pipe can be suppressed, and heat transfer with water is further improved. For this reason, it has the effect | action that the pipe | tube length of the pipe | tube 1 for obtaining required heat exchange capability can be shortened, and more compact and lightweight can be achieved.

  The invention according to claim 3 is the invention according to claim 1 or 2, wherein a gap is provided between the inner wall of the tube 1 and the outer shell of the tube 2 wound in a spiral shape. The main flow of the water flow through the gap between the inner walls suppresses a decrease in the water-side flow rate in the pipe 1 due to an increase in the flow resistance due to the spiral pipe 2, and turbulence is generated in the outer portion of the spiral pipe 2. Promoted and further improved heat transfer capability. For this reason, the tube length of the tube 1 for obtaining the necessary heat exchange capability can be further shortened, and the operation can be further reduced in size and weight.

  According to a fourth aspect of the present invention, in the first to third aspects of the invention, the water flowing in the pipe 1 is formed by having a substantially concentric cavity in the central axis of the spiral of the spiral pipe 2. Mainly flows through the central axis portion of the spiral tube 2 so that the effective contact area of water with the spirally wound tube 2 is increased, and the water flows while being turbulent in the spiral cavity portion. This greatly improves the heat exchange capacity with the refrigerant. For this reason, the tube length of the tube 1 for obtaining the necessary heat exchange capability can be greatly shortened, and there is an effect that a significant reduction in size and weight can be achieved.

  According to a fifth aspect of the present invention, in the first to fourth aspects of the present invention, the water flowing in the pipe 1 is spirally wound by winding it spirally at a pitch wider than the outer diameter of the pipe 2. The heat transfer area of the spirally wound tube 2 is most effectively used by flowing through the gap between the inner wall of the tube 1 and the outer shell of the tube 2 and the central axis of the tube 2 while wrapping around the entire tube. Heat can be transferred to water, and the heat transfer capability with the refrigerant is greatly improved by flowing in the spiral inside the water in a turbulent flow. For this reason, the tube length of the tube 1 for obtaining a necessary heat exchange capability can be significantly shortened, and there is an effect that a more compact and light weight can be achieved.

According to a sixth aspect of the present invention, in the first to fifth aspects of the present invention, the pipe 2 is a double pipe in which the outer pipe and the inner pipe are in close contact, so that the refrigerant in the pipe 2 is made of carbon dioxide. Even when a high-pressure refrigerant such as carbon is used, the double wall for ensuring safety is secured between the pipe 2 and water without reducing the thermal conductivity of the pipe 2.

According to a seventh aspect of the present invention, in the second to sixth aspects of the invention, the outer diameter of the branch pipe forming the pipe 2 is d2 ′, the inner diameter of the pipe 1 is d1, and the inner diameter d1 of the pipe 1 Is 2.1d2 ′ to 2.7d2 ′ and the spiral angle is 4 ° to 60 °, the heat transfer coefficient is optimized while keeping the pressure loss of the water in the pipe 1 small, and the water heat exchanger Has the effect of reducing the size and weight.

The invention according to claim 8 is the invention according to claim 1 or claims 3 to 6 , wherein the number of the tubes 2 is one, the outer diameter of the tube 2 is d2, and the inner diameter of the tube 1 is d1. The tube 1 has an inner diameter d1 of 1.8d2 to 2.2d2 and a helical angle of 6 ° to 70 °, thereby optimizing the heat transfer rate while keeping the pressure loss of water in the tube 1 small. The water heat exchanger is reduced in size and weight, and the tube 2 is spirally wound with a single tube. Therefore, the number of steps such as the holding process of the tube 2 can be reduced and the jigs can be simplified during the spiral processing.

  Embodiments of a heat exchanger according to the present invention will be described below with reference to FIGS.

(Embodiment 1)
1 and 2 are sectional views in the axial direction of a heat exchanger tube 1 for a heat pump type hot water heater in Embodiment 1 of the present invention, and FIG. 3 is a heat exchanger tube 1 in the same embodiment. It is a fragmentary sectional view of the direction of an axis.

  In FIG. 1, 1 is a pipe | tube with which copper water distribute | circulates, 2 is a copper pipe | tube formed in the spiral by the pipe | tube which is included in the pipe | tube 1, and a refrigerant | coolant distribute | circulates, 5 is a heat exchanger main body. .

  In FIG. 2, a copper tube in which a plurality of branch tubes 2 a, 2 b, 2 c branched from a flow divider 3 are spirally wound inside the tube 1.

  Here, as shown in FIG. 3, the inner diameter of the pipe 1 is d1, the outer diameter of the pipe 2 and the branch pipes 2a, 2b, 2c is d2, d2 ′, and the inner diameter of the pipe 2 and the branch pipes 2a, 2b, 2c is d3. It is said. Since the inner diameter d1 of the tube 1 is larger than the outer shell of the tube 2 wound spirally, a gap 6 is provided between the inner wall of the tube 1 and the outer shell of the tube 2 wound spirally.

  Further, there is a relationship of (Equation 1) between the inner diameter d3 of the spirally wound tube 2 and branch tubes 2a, 2b, and 2c and the number N of tubes.

  Further, in the case of FIG. 1, between the inner diameter d1 of the tube 1 and the outer diameter d2 of the tube 2, d1 is 1.8d2 to 2.2d2, and the helical angle θ is 6 ° to 70 °, more preferably 55. It is in the range of ° to 70 °. A spiral angle smaller than 6 ° cannot be regarded as a spiral.

  Furthermore, in the case of FIG. 2, between the inner diameter d1 of the pipe 2 and the outer diameters of the branch pipes 2a, 2b, and 2c, d1 is a spiral having a relationship of 2.1d2 ′ to 2.7d2 ′. The angle θ is 4 ° to 60 °, more preferably 30 ° to 60 °. If the helix angle is less than 4 °, the individual tubes are deformed and cannot be fixed.

The operation of the heat exchanger for the heat pump type hot water heater configured as described above will be described below.

  In FIG. 1, water flows inside the tube 1 and carbon dioxide flows inside the tube 2 as fluids, and water and carbon dioxide exchange heat through a wall 4 (not shown) of the tube 2.

  Here, as shown in FIG. 1, heat from carbon dioxide can be transferred from the entire tube 2 to the water flowing through the tube 1, the heat insulating material attached to the heat exchanger 10 can be simplified, and the heat pump hot water supply When it is incorporated into products such as containers, it can be made compact and lightweight. In addition, as shown in FIG. 2, branch pipes 2a, 2b, 2c branched into a plurality from a flow divider 3 are spirally wound inside a pipe 1 through which water flows, and a refrigerant pipe is included. By diverting, an increase in pressure loss of the refrigerant in the refrigerant pipe due to the spiral winding of the refrigerant pipe can be suppressed, and heat transfer with water is further improved. For this reason, the tube length of the tube 1 for obtaining a necessary heat exchange capability can be further shortened, and further reduction in size and weight can be achieved. In addition, the main flow of water flows through the gap 6 between the inner wall of the pipe 1 and the inner wall of the pipe 1 by the gap 6 between the inner wall of the pipe 1 and the outer shell of the pipe 2 wound in a spiral shape. In addition, a decrease in the water-side flow rate in the pipe 1 due to an increase in flow resistance due to the branch pipes 2a, 2b, and 2c is suppressed, and turbulence is promoted in the outer portion of the spiral pipe 2 and the branch pipes 2a, 2b, and 2c Therefore, the heat transfer capability can be further improved, the heat transfer capability can be further improved, the tube length of the tube 1 for obtaining the necessary heat exchange capability can be further shortened, and further reduction in size and weight can be achieved.

  Further, there is a relationship as shown in FIG. 4 between the inner diameter d3 of the spirally wound tube 2 and branch tubes 2a, 2b, and 2c and the number N. When the inner diameter d3 is reduced, the flow rate of carbon dioxide increases and the heat transfer coefficient increases. However, at the same time, the pressure loss of carbon dioxide increases, so that the average temperature difference between carbon dioxide and water decreases. There is an optimum range of the inner diameter of the pipe 2 that minimizes the weight of the heat exchanger necessary to secure the necessary heat exchange amount due to the influence of both, and this is the inner diameter d3 of the pipe 2 and the branch pipes 2a, 2b, 2c. And the number N is a range in which the relationship of (Equation 1) is established.

  Moreover, there exists a relationship as shown in FIGS. 5 and 6 between the outer diameter d2 and the spiral angle θ of the tube 2 wound spirally as shown in FIG. 1 and the inner diameter d1 of the tube 1.

  In order to secure the necessary heat exchange amount while keeping the pressure loss of water small and constant, if the spiral angle θ is increased, the inner diameter d1 of the tube 1 increases and the heat transfer area increases, but the flow rate decreases and the heat transfer coefficient decreases. There is an optimum range of the outer diameter d2 of the pipe 2 and the inner diameter d1 of the pipe 1 which is the lowest and the highest heat transfer coefficient.

  For this reason, as shown in FIG. 6, there is an optimum range of the inner diameter d1 of the pipe 1 in which the necessary length of the necessary pipe 1 is the shortest while keeping the pressure loss of water small and constant at each spiral angle. There is an optimum range of the inner diameter d1 of the tube 1 and the helix angle θ of the tube 2 where the required heat exchanger weight is the smallest, which is 1.8d2 to 2.2d2 with respect to the outer diameter d2 of the tube 2. The helical angle θ is between 55 ° and 70 °. Further, when the number of the pipes 2 is one, the pipe 2 is wound spirally by one, so that it is possible to reduce man-hours such as a holding process of the pipe 2 during the spiral processing and simplify the jigs and tools.

  Similarly, the outer diameters of the three branch pipes 2a, 2b, and 2c wound spirally as shown in FIG. 2 are set between d2 ′ and the spiral angle θ and the inner diameter d1 of the pipe 1 in FIG. There is a relationship as shown in FIG.

  In this case, the optimum range of the inner diameter d1 of the pipe 1 and the spiral angle θ of the pipe 2 with the smallest necessary heat exchanger weight is 2.4d2 with respect to the outer diameter d2 ′ of the branch pipes 2a, 2b and 2c. '~ 2.7d2' and the spiral angle θ is between 30 ° and 45 °.

  Furthermore, when there are two branch pipes (not shown), similarly, the outer diameter d2 ′ and the spiral angle θ of the branch pipe and the inner diameter d1 of the pipe 1 are shown in FIG. 9 and FIG. There is a relationship.

  In this case, the optimum range of the inner diameter d1 of the pipe 1 and the spiral angle θ of the pipe 2 with the smallest necessary heat exchanger weight is 2.1 d2 ′ to 2.6d2 with respect to the outer diameter d2 ′ of the branch pipe. 'And the helix angle θ is between 45 ° and 60 °.

  In addition, as shown in FIG. 11, by providing a substantially concentric cavity 8 in the spiral central shaft portion 7 of the spiral tube, water flowing in the tube 1 flows through the central shaft portion 7 of the spiral tube 2. By mainly flowing through the cavity 8, the effective contact area of the spirally wound tube 2 and water becomes large, and the heat exchange capacity with the refrigerant by allowing the water to flow while being turbulent in the spiral cavity Greatly improve. For this reason, the tube length of the tube 1 for obtaining the necessary heat exchange capability can be greatly shortened, and a significant reduction in size and weight can be achieved.

  In addition, as shown in FIG. 12, by winding spirally at a pitch wider than the tube outer diameters d2 and d2 ′ of the tube 2, the water flowing in the tube 1 wraps around the entire tube of the spiral tube 2 and By flowing through the gap 9 between the inner wall of 1 and the outer shell of the tube 2 and the central axis portion of the tube 2, the heat transfer area of the spirally wound tube 2 can be most effectively used to transfer heat to water, and The ability of the heat transfer with the refrigerant to be greatly improved by allowing the water to flow in a turbulent flow inside the spiral. For this reason, the tube length of the tube 1 for obtaining a necessary heat exchange capability can be significantly shortened, and a much more compact and light weight can be achieved.

  Further, as shown in FIG. 13, when the pipe 2 is a copper double pipe in which the outer pipe 10 a and the inner pipe 10 b are in close contact, the refrigerant in the pipe 2 becomes a high-pressure refrigerant of carbon dioxide. A double wall is secured between the pipe 2 and the water without reducing the thermal conductivity of the pipe 2.

  In the embodiment of the present invention, the tube 1 is a straight tube, but the same effect can be obtained when the tube 1 is curved or coiled.

  In the embodiment of the present invention, the refrigerant flowing in the pipe 2 is carbon dioxide, but the same effect can be obtained with a refrigerant operating at a high pressure such as R410A.

  The pipe 1, the pipe 2 and the branch pipes 2a, 2b, 2c, the outer pipe 8a and the inner pipe 8b are made of copper, but the same effect can be obtained with brass, SUS, corrosion-resistant iron, aluminum alloy, or the like.

As described above, the heat exchanger for a heat pump type hot water heater according to the present invention encloses a spiral pipe through which a refrigerant flows in a pipe through which water flows, and transfers heat from the refrigerant to water with high efficiency. Therefore, it can be widely applied as a heat exchanger such as a heat pump type hot water heater or a home or commercial air conditioner.

Sectional drawing of the axial direction of the pipe | tube 1 of the heat exchanger for heat pump type hot water heaters in Embodiment 1 of this invention Sectional drawing of the axial direction of the pipe | tube 1 of the heat exchanger for other heat pump type water heaters in the embodiment The fragmentary sectional view of the axial direction of the pipe | tube 1 of the heat exchanger for the heat pump type water heaters of the embodiment The characteristic view which shows the influence of the number of the pipe | tubes 2 with respect to the internal diameter d3 of the pipe | tube 2 of the heat exchanger for heat pump type hot water heaters in the embodiment The characteristic view which shows the influence of helical angle (theta) with respect to the outer diameter d2 of the pipe | tube 2 of the heat exchanger for heat pump type hot water heaters in the embodiment The characteristic view which shows the influence of spiral angle (theta) with respect to the internal diameter d1 of the pipe | tube 2 of the heat exchanger for heat pump type hot water heaters in the embodiment The characteristic view which shows the influence of the helical angle (theta) with respect to the outer diameter d2 of the pipe | tube 2 of the heat exchanger for other heat pump type hot water heaters in the embodiment The characteristic view which shows the influence of the helical angle (theta) with respect to the internal diameter d1 of the pipe | tube 2 of the heat exchanger for other heat pump type hot water heaters in the embodiment The characteristic view which shows the influence of the helical angle (theta) with respect to the outer diameter d2 of the pipe | tube 2 of the heat exchanger for other heat pump type hot water heaters in the embodiment The characteristic view which shows the influence of the helical angle (theta) with respect to the internal diameter d1 of the pipe | tube 2 of the heat exchanger for other heat pump type hot water heaters in the embodiment Sectional drawing of the axial direction of the pipe | tube 1 of the heat exchanger for other heat pump type water heaters in the embodiment Sectional drawing of the axial direction of the pipe | tube 1 of the heat exchanger for other heat pump type water heaters in the embodiment The fragmentary sectional view of the axial direction of the pipe | tube 1 of the heat exchanger for other heat pump type water heaters in Embodiment 1 of this invention Structure of conventional heat exchanger Structure of another conventional heat exchanger

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pipe | tube 2 Spiral pipe | tube 2a, 2b, 2c Branch pipe 3 Divider 5 Heat exchanger 6, 9 Crevice 7 Center axial part 8 Cavity 10a Outer pipe 10b Inner pipe

Claims (8)

A pipe 1 through which water circulates and a pipe 2 through which the refrigerant circulates are formed in a spiral and are enclosed, and the refrigerant circulated in the pipe 2 is carbon dioxide, and the refrigerant circulates and spirals. When the number of the tubes 2 wound around is N and the inner diameter of the tube 2 is d3, there is a relationship of (Equation 1) between the number N of the tubes 2 and the inner diameter d3 of the tube 2. Heat exchanger for heat pump water heater.

The heat exchanger for a heat pump type hot water heater according to claim 1, wherein the pipe 2 is formed by spirally winding a branch pipe branched into a plurality from the flow divider. The heat exchanger for a heat pump type hot water heater according to claim 1 or 2, wherein a gap is provided between the inner wall of the pipe 1 and the outer shell of the pipe 2 wound in a spiral shape. The heat exchanger for a heat pump type hot water heater according to any one of claims 1 to 3, wherein the central axis portion of the spiral of the spiral tube 2 has a substantially concentric cavity. The heat exchanger for a heat pump type hot water heater according to any one of claims 1 to 4, wherein the heat exchanger is wound spirally at an interval wider than a pipe outer diameter of the pipe (2). The heat exchanger for a heat pump type hot water heater according to any one of claims 1 to 5 , wherein the pipe 2 is a double pipe in which an outer pipe and an inner pipe are in close contact with each other. The outer diameter of the branch pipe forming the pipe 2 is d2 ′, the inner diameter of the pipe 1 is d1, the inner diameter d1 of the pipe 1 is 2.1d2 ′ to 2.7d2 ′, and the spiral angle is 4 ° to 60 °. The heat exchanger for a heat pump type water heater according to any one of claims 2 to 6 , wherein the heat exchanger is a heat exchanger. The tube 2 is one, the outer diameter of the tube 2 is d2, the inner diameter of the tube 1 is d1, the inner diameter d1 of the tube 1 is 1.8d2 to 2.2d2, and the spiral angle is 6 ° to 70 °. The heat exchanger for a heat pump type hot water heater according to any one of claims 1 and 3 to 6 , wherein the heat exchanger is provided.

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