JP3922214B2 - Heat exchanger and heat pump water heater using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat exchanger and a heat pump water heater using the heat exchanger, and in particular, to a refrigerant-to-water heat exchanger used in a water heater that generates hot water using a heat pump, an air conditioner that generates cold / hot water, and the like. The present invention relates to a heat exchanger that performs heat transfer between different types of media and a heat pump water heater using the heat exchanger.
[0002]
[Prior art]
Conventionally, as this type of heat exchanger, a double-pipe heat exchanger as shown in FIGS. 5 and 6 has been proposed. The configuration will be described with reference to FIGS. 5 and 6 (see, for example, Patent Document 1).
[0003]
The heat exchanger 50 is used, for example, in a so-called heat pump water heater that heats hot water using the condensation heat of the refrigerant, etc., and the heat exchanger 50 has an inner tube 55 inserted concentrically into the outer tube 56. The heat pipe 51 is formed by winding it in an annular shape. While the inner pipe 55 has a flow path 53 through which high-temperature and high-pressure refrigerant flows, the space between the inner pipe 55 and the outer pipe 56 is used as a flow path 54 through which low-temperature and low-pressure water flows. At this time, the high-temperature refrigerant flows into the inner pipe 55 of the heat transfer pipe 51 in, for example, the direction indicated by the arrow in FIG. 6 and exchanges heat with low-temperature water flowing through the outer flow path 54 in the direction opposite to the arrow. This water will be heated.
[0004]
[Patent Document 1]
JP 2001-201275 A (6th page, FIGS. 2 to 3)
[0005]
[Problems to be solved by the invention]
However, the conventional configuration has the following problems. For example, in order to improve the performance and expand the capacity of the heat exchanger 50, it is necessary to lengthen the entire length of the heat transfer tube 51. At this time, in the conventional configuration, the number of turns of the heat transfer tube 51 wound spirally is increased, or the winding shape is increased to increase the length per turn, thereby increasing the predetermined length of the transfer. The heat pipe length will be secured. In this case, an increase in the number of turns leads to an increase in the height of the heat exchanger, and an increase in the winding shape leads to an increase in the installation area of the heat exchanger. There was a problem of ending up.
[0006]
The present invention solves the above-mentioned conventional problems and provides a compact and highly reliable heat exchanger.
[0007]
[Means for Solving the Problems]
In order to solve the conventional problem, the heat exchanger of the present invention includes a first flow path through which a first fluid flows and a second flow path through which a second fluid flows, and has a substantially circular cross-sectional shape. A first heat transfer tube and a second heat transfer tube , wherein the second heat transfer tube is disposed inside the first heat transfer tube, and the first heat transfer tube and the second heat transfer tube are both spirally wound. The second heat transfer tube has an equivalent diameter smaller than that of the first heat transfer tube .
[0008]
This makes it possible to effectively utilize the space formed inside the heat transfer tube wound in a spiral, improve the heat exchanger mounting density, and minimize the storage space. Can be provided. In addition, the heat transfer tube can be easily lengthened, and high performance and capacity expansion of the heat exchanger can be easily realized.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The invention according to claim 1 includes a first heat transfer tube and a second heat transfer tube that include a first flow path through which the first fluid flows and a second flow path through which the second fluid flows, and have a substantially circular cross-sectional shape. The second heat transfer tube is disposed inside the first heat transfer tube, and the first heat transfer tube and the second heat transfer tube are both spirally wound to correspond to the second heat transfer tube. The diameter is smaller than that of the first heat transfer tube , and the space formed inside the heat transfer tube wound spirally is effectively used to improve the mounting density of the heat exchanger. Therefore, the storage space can be minimized, and a heat exchanger that is compact and excellent in the ability to be stored in a device can be provided. In addition, the heat transfer tube can be easily lengthened, and high performance and capacity expansion of the heat exchanger can be easily realized. Furthermore, by arranging a small R-shaped thin tube that is easy to bend in general inside the double structure, it is possible to provide a heat exchanger that is more compact and excellent in storability.
[0010]
The invention according to claim 2 is a double arrangement in which the bending radius of the second heat transfer tube wound spirally is smaller than that of the first heat transfer tube. In addition, since the gap between the first heat transfer tube and the second heat transfer tube can be minimized, a more compact and excellent heat exchanger can be provided.
[0011]
The invention according to claim 3 is the one in which the height in the winding axis direction of the second heat transfer tube wound in a spiral shape is larger than that of the first heat transfer tube in the configuration of claim 1 or 2. And since the connection with the exterior of the 2nd heat exchanger tube arranged inside the double structure becomes easy, a compact and excellent heat exchanger can be provided.
[0012]
In the invention according to claim 4 , the first and second heat transfer tubes communicate with the configuration according to claims 1 to 3 in the vertical upper side in the winding axis direction, and the structure of the entire heat exchanger As an inflow from the lower side in the vertical direction, the fluid rises and falls in the heat exchanger, and finally flows out again from the lower side in the vertical direction. Therefore, maintenance such as drainage using gravity as an anti-freezing measure is facilitated, and a compact and highly reliable heat exchanger can be provided.
[0013]
The invention according to claim 5 is the structure of the first to fourth aspects , in which the first and second heat transfer tubes are composed of a continuous continuous pipe body. Since there is a low possibility of fluid leakage or the like due to poor connection at the joint and the configuration can be simplified, a heat exchanger that is compact and excellent in reliability and productivity can be provided.
[0014]
Invention of Claim 6 is a heat pump water heater which heats water with a refrigerant | coolant, and the heat exchanger of Claims 1-5 is comprised from a compressor, a radiator, an expansion valve, and an evaporator at least. It is used as a heat pump circuit radiator and heats the second fluid water with the first fluid refrigerant. By using the compact and highly reliable heat exchanger of this embodiment, the heat pump water heater as a whole Compactness and improved reliability can be realized.
[0015]
According to the seventh aspect of the invention, in contrast to the configuration of the sixth aspect , in particular, the pressure of the refrigerant is equal to or higher than the critical pressure, and the refrigerant as the first fluid flowing through the heat exchanger is a critical pressure by a compressor. Since it is pressurized as described above, it does not condense even if the temperature is lowered due to heat being taken away by water as the second fluid. Therefore, it becomes easy to form a temperature difference between the refrigerant and water in the entire heat exchanger, high-temperature hot water can be obtained, and heat exchange efficiency can be increased.
[0016]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
[0017]
Example 1
1 and 2 are a side view and a plan view of a heat exchanger 10 in Embodiment 1 of the present invention. 1 and 2, a heat exchanger 10 includes first and second heat transfer tubes 1 and 2 that include a first flow path 3 through which a first fluid flows and a second flow path 4 through which a second fluid flows. And the two heat transfer tubes 2 have a configuration in which the two heat transfer tubes 2 are double-arranged inside the wound first heat transfer tube 1.
[0018]
The first heat transfer tube 1 includes an inner tube 5 and an outer tube 6, and is configured by inserting the inner tube 5 concentrically into the outer tube 6 and winding it in a spiral shape. While the inner pipe 5 is used as the first flow path 3a through which the first fluid (for example, high-temperature and high-pressure refrigerant) flows, the space between the inner pipe 5 and the outer pipe 6 is used for the second fluid (for example, low-temperature and low-pressure water). ) Through which the second flow path 4a flows. Similarly, the second heat transfer tube 2 includes an inner tube 7 and an outer tube 8, and is configured by inserting the inner tube 7 concentrically into the outer tube 8 and winding it spirally. The inner pipe 7 serves as a first flow path 3b through which a first fluid (for example, a high-temperature and high-pressure refrigerant) flows, while a space between the inner pipe 7 and the outer pipe 8 serves as a second fluid (for example, low-temperature and low-pressure water). ) Through which the second flow path 4b flows. At this time, the height H2 of the second heat transfer tube 2 is configured to be greater than the height H1 of the first heat transfer tube 1 with respect to the winding axis direction indicated by the arrow A in FIG. Moreover, the cross section of the 1st heat exchanger tube 1 and the 2nd heat exchanger tube 2 has a substantially circular shape, and the equivalent diameter D2 of the 2nd heat exchanger tube 2 is comprised smaller than the equivalent diameter D1 of the 1st heat exchanger tube 1. .
[0019]
Note that the first flow paths 3 a and 3 b through which the first fluid flows are in communication with each other in the connection pipe 11 to form a continuous first flow path 3. Similarly, the second flow paths 4 a and 4 b through which the second fluid flows are in communication with each other in the connection pipe 12 to form a continuous second flow path 4. At this time, the first heat transfer tube 1 and the second heat transfer tube 2 communicate with each other in the vertical direction above the winding axis direction indicated by the arrow A in FIG. Further, as shown in FIG. 2, the heat exchanger 10 is configured such that the bending radius R <b> 2 of the second heat transfer tube 2 wound spirally is smaller than the bending radius R <b> 1 of the first heat transfer tube 1.
[0020]
Examples of the material of the tube constituting the heat exchanger 10 include metals having good thermal conductivity and formability, such as copper, aluminum, iron, and stainless steel.
[0021]
The effect | action is demonstrated below about the heat exchanger 10 comprised as mentioned above.
[0022]
In the first heat transfer tube 1 and the second heat transfer tube 2, the first fluid on the high pressure side is passed through the first flow path 3, and the second fluid on the low pressure side is passed through the second flow path 4. When the heat exchanger 10 is used in a refrigerant water heat exchanger of a so-called heat pump water heater that heats hot water using the condensation heat or sensible heat of a compressed refrigerant, as shown in FIG. The first high-pressure fluid is a refrigerant such as carbon dioxide or chlorofluorocarbon sent from the compressor, and the second low-pressure fluid is water for hot water supply.
[0023]
In general, a heat pump water heater includes a heat pump circuit 35 in which a compressor 31, a heat exchanger 10 as a radiator, an expansion valve 33, an evaporator 34 for collecting atmospheric heat and the like are sequentially connected, a hot water storage tank 36, and a water pump 37. And a water circuit 38 in which the heat exchangers 10 are sequentially connected.
[0024]
When heating hot water with such a heat pump water heater, first, the evaporator 34 collects atmospheric heat, solar heat, etc. by a blower fan, a heat collecting panel, etc., and evaporates the refrigerant flowing in the air. . This refrigerant is sucked into the compressor 31, mechanically compressed, and sent to the first flow path 3 of the heat exchanger 10 as a high-temperature and high-pressure refrigerant.
[0025]
The water in the lower part of the hot water storage tank 36 is conveyed by a circulating water pump 37 and flows into the second flow path 4 of the heat exchanger 10. Here, the high-temperature and high-pressure refrigerant flows into the first heat transfer tube 1 and flows out of the second heat transfer tube 2 through the connection tube 11 as indicated by solid arrows in FIG.
[0026]
On the other hand, when low-temperature and low-pressure water is flowed in the opposite direction, a counter-current flow excellent in heat exchange performance can be obtained as a heat transfer mode. At this time, the high-temperature and high-pressure refrigerant flowing through the first flow paths 3a and 3b exchanges heat with the low-temperature and low-pressure water flowing through the second flow paths 4a and 4b located therearound via the inner pipes 5 and 7. Will do. While flowing through the second flow path 4, the low-temperature hot water supply water receives heat from the high-temperature refrigerant and becomes high-temperature hot water, and flows into the hot water storage tank 36.
[0027]
The refrigerant radiated by the heat exchanger 10 is decompressed by the expansion valve 33 and flows into the evaporator 34. Here, the refrigerant again absorbs heat from atmospheric heat or the like and is supplied to the next compressor 31.
[0028]
In addition to the carbon dioxide refrigerant, examples of the refrigerant used for the heat pump water heater include a fluorocarbon refrigerant such as R410a and a hydrocarbon refrigerant such as propane and butane.
[0029]
According to the present embodiment, by arranging the second heat transfer tube 2 inside the first heat transfer tube 1, the space formed inside the first heat transfer tube 1 wound spirally is effectively utilized. And the mounting density of the heat exchanger 10 whole can be improved, the storage space can be minimized, and the storage property to equipment such as a heat pump water heater can be sufficiently secured. Further, when the heat exchanger tube is lengthened as necessary to increase the performance and capacity of the heat exchanger 10, it is excellent in compactness, so that these can be easily realized.
[0030]
Moreover, since the bending radius R2 of the 2nd heat exchanger tube 2 wound helically is smaller than the bending radius R1 of the 1st heat exchanger tube 1, the 1st heat exchanger tube 1 and the 2nd heat exchanger tube 2 which were arrange | positioned doubly. The gap between the two can be minimized, and the dead space can be reduced.
[0031]
Moreover, when the bending radius R2 of the 2nd heat exchanger tube 2 is larger than the bending radius R1 of the 1st heat exchanger tube 1, a straight part is provided in the bending location of the 1st heat exchanger tube 1, and the whole is made into substantially square shape. This is necessary, and is accompanied by an increase in dead space, an increase in the number of bending processes, and a decrease in productivity.
[0032]
Furthermore, since the cross section of the first and second heat transfer tubes 1 and 2 has a substantially circular shape and the equivalent diameter D2 of the second heat transfer tube 2 is smaller than the equivalent diameter D1 of the first heat transfer tube 1, the inner and outer double A more compact heat exchanger can be configured by arranging small R-shaped thin tubes that are generally easy to bend inside the structure.
[0033]
Here, consider the case where the heat exchanger 10 of the present embodiment is applied to, for example, a refrigerant-to-water heat exchanger that heats water (particularly tap water) with a refrigerant. In general, when water containing a large amount of hardness components such as calcium and magnesium is heated to a high temperature for a long period of time with such a refrigerant-to-water heat exchanger, a scale is generated in the vicinity of the outlet portion of the water-side channel that is at the highest temperature. there is a possibility. When such a scale adheres to the inner periphery of the water-side flow path, it becomes water flow resistance and pressure loss increases, and it becomes heat resistance of the heat transfer surface and reduces the performance as a heat exchanger.
[0034]
Assuming such a case, in this embodiment, the equivalent diameter D1 of the first heat transfer tube 1 on the high temperature side for water is made larger than the equivalent diameter D2 of the second heat transfer tube 2 on the low temperature side. Since the cross-sectional area of the second flow path 4a between the pipe 5 and the outer pipe 6 is configured to be larger than the cross-sectional area of the second flow path 4b between the inner pipe 7 and the outer pipe 8, by any chance Even when scales or the like are generated and adhered in the channel, the increase in the flow resistance of water is mitigated, and the life of the heat exchanger is extended.
[0035]
Further, the height H2 of the second heat transfer tube 2 wound in a spiral shape in the direction of the winding axis A is larger than the height H1 of the first heat transfer tube 1, and is arranged inside the double structure. Further, since the second heat transfer tube 2 does not interfere with the first heat transfer tube 1 and the pipe connection with the first heat transfer tube 1 or the outside becomes easy, a compact and highly productive heat exchanger is provided. be able to.
[0036]
Further, the first and second heat transfer tubes 1 and 2 communicate with each other on the vertical upper side in the direction of the winding axis A. As a structure of the entire heat exchanger, the first heat transfer tubes 1 and 2 flow in from the lower side in the vertical direction. An inverted U-shaped configuration can be adopted in which the fluid rises and falls and finally flows out again from the lower side in the vertical direction. This is because, for example, when water is drained as a measure to prevent freezing of the heat exchanger in winter, if both ends of the second flow path 4 are opened to the atmosphere, water is not trapped in the heat exchanger and is easily trapped by gravity. This means that water can be drained. Therefore, maintenance such as draining becomes easy.
[0037]
Further, the heat exchanger 10 of the present embodiment is used as a radiator of a heat pump circuit including at least a compressor, a radiator, an expansion valve, and an evaporator, and the water of the second fluid is heated by the refrigerant of the first fluid. By using a compact and highly reliable heat exchanger, the heat pump water heater as a whole can be downsized and improved in reliability.
[0038]
In particular, if oxygen dioxide or the like is used as the refrigerant and the pressure thereof is equal to or higher than the critical pressure, the refrigerant that is the first fluid flowing through the heat exchanger is pressurized to the critical pressure or higher by the compressor. The heat is taken away by the water as the second fluid and does not condense even if the temperature drops, and it becomes easy to form a temperature difference between the refrigerant and the water throughout the heat exchanger, and hot water is obtained, and Heat exchange efficiency can be increased.
[0039]
Therefore, it is possible to provide a heat exchanger that is compact and excellent in storage property in equipment and that is excellent in productivity, reliability, and heat transfer performance.
[0040]
(Example 2)
FIG. 4 is a side view of the heat exchanger 20 according to the second embodiment of the present invention. Since the overall configuration and operation of the heat exchanger of the present embodiment are substantially the same as those of the heat exchanger 10 shown in FIG. 1, detailed description thereof is omitted here. The difference from the first embodiment is that the first heat transfer tube 1 and the second heat transfer tube 2 are formed of a continuous tube body without a joint. Such a configuration spirals the tube body in the form of the first heat transfer tube 1 so as to surround the outer periphery continuously after the tube body is spirally wound in the form of the second heat transfer tube 2 disposed inside. What is necessary is just to wind in the shape, and it can implement | achieve easily.
[0041]
Therefore, according to the present embodiment, as described in the first embodiment, the heat exchanger can be configured by a continuous tube body without providing a connecting pipe between the pipes arranged inside and outside. In addition, the possibility of fluid leakage or the like due to poor connection between the connecting portions of the tubes is low, and the configuration can be simplified. Therefore, it is possible to provide a heat exchanger that is compact and excellent in reliability and productivity.
[0042]
In the first embodiment, the first heat transfer tube 1 and the second heat transfer tube 2 have different cross-sectional shapes, but of course, they may have the same cross-sectional shape.
[0043]
Further, in each of the above-described embodiments, the first and second heat transfer tubes are assumed to be double tubes composed of an inner tube and an outer tube. However, the present invention is not limited to this as long as it has a substantially tubular form. Absent. For example, each heat transfer tube may be a so-called triple tube configured as a double tube in which an inner tube is covered with a smooth tube and an inner grooved tube, so that fluid leakage due to damage to the tube due to corrosion or the like may occur. It is detected in advance through the inner groove, and the reliability of the heat exchanger can be further expanded. In addition, other examples of such heat transfer tubes are substantially tubular, such as those in which a thin tube is spirally wound around the outer periphery of the round tube, and a plurality of thin tubes arranged concentrically around the round tube. Any type can be used as long as it can be wound spirally.
[0044]
【The invention's effect】
As described above, according to the present invention, the space formed inside the heat transfer tube wound spirally is effectively used to improve the mounting density of the heat exchanger, and the storage space and thus the entire apparatus can be improved. A compact and excellent heat exchanger can be provided without changing the size. In addition, the heat transfer tube can be easily lengthened, and high performance and capacity expansion of the heat exchanger can be easily realized.
[0045]
Further, by using the heat exchanger of the present invention that is compact and excellent in reliability, it is possible to realize a compact heat pump water heater and an improvement in reliability.
[Brief description of the drawings]
1 is a side view of a heat exchanger according to a first embodiment of the present invention. FIG. 2 is a plan view of a heat exchanger according to a first embodiment of the present invention. FIG. 3 uses the heat exchanger according to a first embodiment of the present invention. Fig. 4 is a side view of a heat exchanger according to a second embodiment of the present invention. Fig. 5 is a side view of a conventional heat exchanger. Fig. 6 is a plan view of a conventional heat exchanger. Explanation of]
DESCRIPTION OF SYMBOLS 1 1st heat exchanger tube 2 2nd heat exchanger tube 3, 3a, 3b 1st flow path 4, 4a, 4b 2nd flow path 10 Heat exchanger

Claims (7)

Enclosing a second flow path first flow path and the second fluid first fluid flow flows, and a first heat transfer pipe and the second heat transfer pipe cross section is substantially circular, the second heat transfer pipe Is arranged inside the first heat transfer tube, the first heat transfer tube and the second heat transfer tube are both spirally wound, and the equivalent diameter of the second heat transfer tube is larger than that of the first heat transfer tube. A heat exchanger characterized by being small .   The heat exchanger according to claim 1, wherein a bending radius of the second heat transfer tube wound spirally is smaller than that of the first heat transfer tube. The heat exchanger according to claim 1 or 2 , wherein a height of the second heat transfer tube wound in a spiral shape in a winding axis direction is larger than that of the first heat transfer tube. The heat exchanger according to any one of claims 1 to 3 , wherein the first heat transfer tube and the second heat transfer tube communicate with each other vertically above the winding axis. The heat exchanger according to any one of claims 1 to 4 , wherein the first heat transfer tube and the second heat transfer tube are constituted by a continuous tubular body having no seams. A heat pump circuit including at least a compressor, a radiator, an expansion valve, and an evaporator is provided, and the radiator uses the heat exchanger according to any one of claims 1 to 5 and uses a first fluid refrigerant. A heat pump water heater for heating the water of the second fluid. The heat pump water heater according to claim 6 , wherein the pressure of the refrigerant is equal to or higher than the critical pressure.

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