JP7012204B2 - Heat exchanger and water heater equipped with it - Google Patents

Description

The present invention relates to a heat exchanger.

Conventionally, in a heat exchanger used in this type of heat pump water heater, the heat exchanger consists of an inner pipe that constitutes a water passage and an outer pipe that is spirally wound around the outer circumference of the inner pipe to form a refrigerant passage. Disclosed is a configuration in which the water flowing through the water is heated by the refrigerant flowing through the refrigerant passage (see, for example, Patent Document 1).

FIG. 8 shows the configuration of this conventional heat exchanger.

The heat exchanger 101 is composed of an inner tube 102 and an outer tube 103 spirally wound around the outer circumference of the inner tube 102 at a predetermined pitch.

The flow of water flowing inside the inner pipe 102 and the flow of the refrigerant flowing inside the outer pipe 103 face each other to exchange heat. Then, one or more outer tubes 103 are wound around the outer periphery of the inner tube 102, and a twisted tape-shaped inserter 104 is inserted inside the inner tube 102 as a heat transfer promoting means.

In the heat exchanger 101 configured as described above, low-temperature water flowing inside the inner pipe 102 and high-temperature carbon dioxide flowing inside the outer pipe 103 flow in opposite directions to exchange heat, for example. It is possible to boil water at about 9 ° C to about 90 ° C.

At this time, the water flowing through the inner pipe 102 is swirled and agitated along the spiral surface of the insert body 104 to promote heat transfer and efficiently exchange heat.

As described above, the heat pump type water heater using carbon dioxide as a refrigerant can generate hot water having a very high temperature.

Japanese Unexamined Patent Publication No. 2005-221172

However, in the conventional configuration, the outer diameter of the insert body 104 has a certain gap with respect to the inner diameter of the inner tube 102 in order to improve the insertability of the insert body 104 into the inner tube 102 at the time of assembling.

Therefore, there is a problem that a water flow flowing in the axial direction is generated in the gap, the flow rate of water swirling and agitated along the spiral surface of the insert 104 is reduced, and the heat transfer promoting effect is reduced.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a heat exchanger that achieves both assemblability and heat exchange performance.

In order to solve the above-mentioned conventional problems, the heat exchanger of the present invention has an inner pipe through which the first fluid flows, a shaft portion, and a protrusion formed on the outer surface of the shaft portion, and the heat exchanger has the inner pipe. The inserted body is provided with an insert body, a flow path of the first fluid formed by an inner surface of the inner tube, an outer surface of the shaft portion, and a side surface of the protrusion, and the first fluid is heated. If not, the gap between the tip of the protrusion and the inner surface of the inner pipe is characterized in that it is larger on the outlet side of the first fluid than on the inlet side of the first fluid. ..

As a result, when the first fluid is not heated, including when the heat exchanger is assembled, the gap between the tip of the protrusion and the inner surface of the inner pipe is larger on the outlet side of the first fluid, so that it is inserted. It is possible to facilitate the insertion of the body and improve the air bleeding performance from the flow path of the first fluid.

On the other hand, when the first fluid is heated, the temperature on the outlet side of the first fluid is higher than that on the inlet side of the first fluid, and the temperature on the outlet side of the first fluid of the insert is higher than that of the first fluid of the insert. Since the heat expands more than the inlet side, the gap between the tip of the protrusion and the inner surface of the inner pipe becomes smaller over the entire flow path of the first fluid, and the water flow through the gap can be reduced, improving heat exchange performance. Can be improved.

According to the present invention, it is possible to provide a heat exchanger that achieves both assembleability and heat exchange performance.

Partial sectional view of the heat exchanger according to the first embodiment of the present invention. Sectional drawing which shows the structure of the part A when the 1st fluid is not heated of the same heat exchanger. Sectional drawing which shows the structure of the part A at the time of assembling the same heat exchanger Sectional drawing which shows the structure of the part A at the time of the 1st fluid heating of the same heat exchanger The figure which shows the temperature distribution characteristic of the same heat exchanger The figure which shows the change of the expansion dimension of the insert body of the same heat exchanger The figure which shows the change of the design outer diameter of the insert body of the same heat exchanger Configuration diagram showing the insert of a conventional heat exchanger and its surroundings

The first invention has an inner tube through which a first fluid flows, a shaft portion, and an insert body having a protrusion formed on an outer surface of the shaft portion, and is inserted into the inner tube, and the inner tube. A flow path of the first fluid formed by an inner surface, an outer surface of the shaft portion, and a side surface of the protrusion, and when the first fluid is not heated, the tip portion of the protrusion. The heat exchanger is characterized in that the gap between the inner surface and the inner surface of the inner pipe is larger on the outlet side of the first fluid than on the inlet side of the first fluid.

As a result, when the first fluid is not heated, including when the heat exchanger is assembled, the gap between the tip of the protrusion and the inner surface of the inner pipe is larger on the outlet side of the first fluid, so that it is inserted. It is possible to easily insert the body and improve the air bleeding performance from the flow path of the first fluid.

On the other hand, when the first fluid is heated, the temperature on the outlet side of the first fluid is higher than that on the inlet side of the first fluid, and the temperature on the outlet side of the first fluid of the insert is higher than that of the first fluid of the insert. Since the heat expands more than the inlet side, the gap between the tip of the protrusion and the inner surface of the inner pipe becomes smaller over the entire flow path of the first fluid, and the water flow through the gap can be reduced, improving heat exchange performance. Can be improved.

The second invention is characterized in that, particularly in the first invention, the outer diameter of the shaft portion is smaller on the outlet side of the first fluid than on the inlet side of the first fluid. That is, the outer diameter of the insert is gradually changed from the inlet side of the first fluid toward the outlet side of the first fluid.

This makes it easy to insert the insert. Further, when the first fluid is heated, the temperature of the first fluid gradually rises from the inlet side of the first fluid to the outlet side of the first fluid, so that it expands when the first fluid is heated and the temperature rises. By considering and reflecting the outer diameter of the insert in advance, the gap between the tip of the protrusion and the inner surface of the inner tube during heating of the first fluid can be minimized over the entire area, and heat exchange can be performed. The performance can be further improved.

The third invention, particularly in the first or second invention, is characterized in that the linear expansion coefficient of the material forming the insert is larger than the linear expansion coefficient of the material forming the inner tube. be.

As a result, when the first fluid is heated, the expansion ratio of the insert is larger than that of the inner tube, so that the gap between the tip of the protrusion and the inner surface of the inner tube can be made smaller, and the gap flows when the first fluid is heated. The water flow can be made smaller and the performance of the heat exchanger can be improved.

In the fourth invention, particularly in any one of the first to third inventions, an outer pipe through which a second fluid flows is provided on the outer surface of the inner pipe, and the first fluid is heated by the second fluid. It is characterized by that.

Thereby, the high temperature first fluid can be generated by heating the low temperature first fluid with the high temperature second fluid.

The fifth invention is a heat pump water heater provided with the heat exchanger of the fourth invention in which the first fluid is water and the second fluid is a refrigerant.

This makes it possible to provide a heat pump water heater in which a high-temperature refrigerant flowing through an outer pipe provided on the outer surface of the inner pipe heats water to generate hot water.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to this embodiment.

(Embodiment 1)
FIG. 1 is a partial cross-sectional view of a heat exchanger according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view showing the configuration of part A of the heat exchanger when the first fluid is not heated. FIG. 3 is a cross-sectional view showing the configuration of part A at the time of assembling the heat exchanger. FIG. 4 is a cross-sectional view showing the configuration of part A when the first fluid of the heat exchanger is heated. FIG. 5 is a diagram showing the temperature distribution characteristics of the heat exchanger. FIG. 6 is a diagram showing changes in the expansion dimension of the insert body of the heat exchanger. FIG. 7 is a diagram showing changes in the design outer diameter of the insert body of the heat exchanger.

In FIG. 1, the heat exchanger 1 has an inner pipe 2 through which a first fluid (for example, water) flows, an inserter 3 inserted inside the inner pipe 2, and a second fluid (for example, carbon dioxide) inside. It is composed of at least one outer pipe 4 through which a carbon refrigerant) flows and is in close contact with the outer periphery of the inner pipe 2.

Then, the low-temperature first fluid and the high-temperature second fluid flow in opposition to exchange heat, and heat the first fluid to a high temperature.

The heat exchanger 1 is mounted on a water heater (for example, a heat pump water heater using carbon dioxide as a refrigerant), and a second fluid (for example, a carbon dioxide refrigerant) compressed to a high temperature and high pressure by the heat pump device is an outer pipe. It flows inside 4.

Then, in the heat exchanger 1, the second fluid compressed to a high temperature and high pressure flowing inside the outer pipe 4 flows in opposition to the first fluid, which is low-temperature water flowing inside the inner pipe 2, to exchange heat. do.

In this way, the first fluid, which is water, is heated by the second fluid compressed to high temperature and high pressure by the heat pump device flowing inside the outer pipe 4, and the heating operation of hot water is performed to generate high temperature. Water is used for hot water supply.

The outer pipe 4 is spirally wound around the outer circumference of the inner pipe 2 at a predetermined pitch, and a flow path 7 through which water flows is formed between the inner pipe 2 and the insert body 3.

The insert 3 includes a shaft portion 5 and a protrusion 6 formed spirally on the outer surface of the shaft portion 5, and the first fluid is an inner surface of the inner pipe 2 and an outer surface of the shaft portion 5 and a protrusion portion 6. It flows through the spiral flow path 7 formed by the side surface.

As shown in FIGS. 2 and 3, the insert body 3 has a different diameter shape in which one end of the outer diameter is a large diameter Din1 and the other end is a small diameter Dout1 and is inserted into the inlet side of the inner pipe 2 of the first fluid. The insert body 3 is inserted and arranged in the inner tube 2 so that the large-diameter Din1 side of the body 3 is located on the outlet side of the inner tube 2 of the first fluid and the small-diameter Dout1 side of the insert body 3 is located.

The inner pipe 2 is a pipe having an inner diameter D0 and is constant, and the gap Cout1 between the inner surface of the inner pipe 2 and the tip of the protrusion 6 at the outlet portion of the inner pipe 2 of the first fluid is inside the first fluid. The structure is larger than the gap Cin1 between the inner surface of the inner pipe 2 and the tip of the protrusion 6 at the inlet portion of the pipe 2.

Here, when the first fluid including the time of assembling the heat exchanger 1 is not heated by the heating operation, the outer diameter of the inner tube 2 of the first fluid of the insert body 3 is set to Din1 and the insert body 3 is set. The outer diameter at the outlet of the inner pipe 2 of the first fluid is Dout1.

Further, the gap between the inner surface of the inner pipe 2 and the tip of the protrusion 6 at the inlet of the inner pipe 2 of the first fluid is Cin1, and the gap between the inner surface of the inner pipe 2 and the tip of the protrusion 6 is the first fluid. The gap at the outlet of the inner pipe 2 of the above is described as Cout1.

On the other hand, as shown in FIG. 4, when the first fluid is heated by the heating operation, the outer diameter at the inlet portion of the inner tube 2 of the first fluid of the insert body 3 is set to Din2 and the first of the insert body 3. The outer diameter at the outlet of the fluid inner pipe 2 is Dout2.

Further, the gap between the inner surface of the inner pipe 2 and the tip of the protrusion 6 at the inlet of the inner pipe 2 of the first fluid is Cin2, and the gap between the inner surface of the inner pipe 2 and the tip of the protrusion 6 is the first fluid. The gap at the outlet of the inner pipe 2 is referred to as Cout2.

In the heat pump water supply machine, in the heat exchanger 1, the second fluid compressed to high temperature and high pressure flowing inside the outer pipe 4 flows in opposition to the first fluid which is low temperature water flowing inside the inner pipe 2. As a result, heat is exchanged, and water, which is the first fluid, is heated by a high-temperature second fluid (for example, a carbon dioxide refrigerant) flowing inside the outer pipe 4, and a heating operation of hot water is performed.

Hereinafter, the characteristics of the heat exchanger 1 when the first fluid including the time of assembling the heat exchanger 1 is not heated by the heating operation will be described.

As shown in FIGS. 2 and 3, the outer diameter of the insert 3 is larger on the inlet side of the first fluid than on the outlet side of the first fluid. That is, the outer diameter of the insert 3 gradually decreases from the inlet side of the first fluid toward the outlet side of the first fluid so that Din1> Dout1.

Therefore, the inner pipe 2 is a pipe having an inner diameter D0 and is constant, and the gap Cout1 between the inner surface of the inner pipe 2 and the tip of the protrusion 6 at the outlet portion of the inner pipe 2 of the first fluid is the first fluid. The gap between the inner surface of the inner pipe 2 and the tip of the protrusion 6 at the inlet of the inner pipe 2 is larger than Cin1, and the gap between the inner surface of the inner pipe 2 and the tip of the protrusion 6 is the first. The shape is such that the gap gradually increases from the inlet side of the fluid toward the outlet side of the first fluid.

Therefore, as shown in FIG. 3, when assembling the heat exchanger 1, the insertion body 3 can be smoothly inserted into the inner tube 2, the insertion work efficiency is improved, and the assembling property can be improved.

Further, it is formed by the inner surface of the inner pipe 2, the outer surface of the shaft portion 5, and the side surface of the protrusion 6, and has an effect of improving the air bleeding property from the spiral flow path 7 through which the first fluid (for example, water) flows. ..

Hereinafter, the characteristics of the heat exchanger 1 when the first fluid (for example, water) is heated by the heating operation and is in a high temperature state will be described.

When the first fluid is heated by the heating operation, the outer diameter of the insert 3 becomes Dout2> Dout1 due to thermal expansion. Further, since the outlet side of the inner tube 2 of the first fluid has a higher temperature than the inlet side of the inner tube 2 of the first fluid, the outlet side of the first fluid of the insert 3 is the first of the insert 3. It expands more thermally than the inlet side of the fluid.

Therefore, as shown in FIG. 4, when the first fluid is heated by the heating operation, between the inner surface of the inner pipe 2 and the tip of the protrusion 6 at the outlet portion of the inner pipe 2 of the first fluid. When the first fluid including the time of assembling the heat exchanger 1 is not heated by the heating operation, the gap Cout2 of the inner surface of the inner pipe 2 and the protrusion 6 at the outlet of the inner pipe 2 of the first fluid The gap between the tip and the tip is smaller than Cout 1, and the gap between the tip of the protrusion 6 and the inner surface of the inner pipe 2 is smaller over the entire flow path 7 of the first fluid. The water flow in the axial direction of is reduced, and the heat exchange performance is improved.

Specifically, a heat exchanger 1 having a length of 400 mm in which water, which is the first fluid, is heated by the carbon dioxide refrigerant which is the second fluid will be described as an example.

As shown in FIG. 5, the temperature of water, which is the first fluid flowing through the heat exchanger 1 heated under predetermined conditions, is from 20 ° C. on the water inlet side of the inner pipe 2 to the water outlet side of the inner pipe 2. The temperature gradually rises to 60 ° C. At this time, due to the influence of the temperature rise, the outer diameter of the insert 3 made of PPS resin (reinforced type: linear expansion coefficient 4E-5 / K) is, as shown in FIG. 6, on the water outlet side of the inner pipe 2. It can be seen that it expands to about +0.06 mm.

By assuming the expansion of the insert 3 as shown in FIG. 6 in advance, as shown in FIG. 7, when the first fluid including the time of assembling the heat exchanger 1 is not heated by the heating operation. The outer diameter of the insert 3 can be designed to be smaller by the amount of expansion toward the water outlet side of the insert 3.

That is, since the gap between the tip of the protrusion 6 and the inner surface of the inner pipe 2 is larger on the outlet side of the first fluid than on the inlet side of the first fluid, when the heat exchanger 1 is assembled. In a low temperature state where the first fluid containing the above is not heated by the heating operation, the insertability of the insert 3 is facilitated at the time of assembling the heat exchanger 1.

Then, when the heating operation for heating the first fluid is performed to change the temperature to a high temperature state, the outlet side of the inner pipe 2 of the first fluid becomes higher than the inlet side of the inner pipe 2 of the first fluid. Since the outlet side of the first fluid of the insert body 3 thermally expands more than the inlet side of the first fluid of the insert body 3, the gap between the tip portion of the protrusion 6 and the inner surface of the inner tube 2 is formed. Since the size is reduced over the entire flow path 7 of the first fluid, when the first fluid is heated, the water flow flowing in the axial direction of the insert 3 through the gap is reduced, and the heat exchange performance can be improved.

In this way, the water temperature that gradually rises from the inlet side of the first fluid of the insert body 3 to the outlet side of the first fluid is predicted in advance, and the expansion dimension calculated from the prediction is used as the outer diameter dimension of the insert body 3. By reflecting so that the outlet side (high temperature side) of the first fluid is made smaller in diameter, the gap between the tip portion of the protrusion 6 and the inner surface of the inner pipe 2 is minimized over the entire flow path 7 of the first fluid. The heat exchange performance can be further improved.

Further, PPS resin (reinforced type: linear expansion coefficient 4E-5), which is a material having a larger linear expansion coefficient than copper (linear expansion coefficient 16.8E-6 / K), which is a material forming the inner tube 2, is used. When the insert 3 is formed with / K), the gap between the inner surface of the inner tube 2 and the tip of the protrusion 6 when the first fluid (for example, water) is heated by the heating operation is made smaller. It is possible to further improve the heat exchange performance.

In the first embodiment, carbon dioxide is used as the fluid flowing in the outer pipe 4, but it is also possible to use a hydrocarbon-based or HFC-based (R410A, R32, etc.) refrigerant or an alternative refrigerant thereof. Can be expected.

Further, although copper and PPS are cited as the materials of the inner tube 2 and the insert body 3, if there is a similar difference in the linear expansion coefficient of the materials, the same effect is obtained, so the type is not particularly limited.

As described above, the heat exchanger according to the present invention can provide a heat exchanger that achieves both assemblability and heat exchange performance. Therefore, a device equipped with a heat exchanger that exchanges heat between fluids such as water. Can be applied to.

1 Heat exchanger 2 Inner pipe 3 Insert 4 Outer pipe 5 Shaft 6 Protrusion 7 Flow path

Claims (5)

The inner pipe through which the first fluid flows and
An insert body having a shaft portion and a protrusion formed on the outer surface of the shaft portion and inserted into the inner tube, and
The flow path of the first fluid formed by the inner surface of the inner pipe, the outer surface of the shaft portion, and the side surface of the protrusion portion, and the flow path of the first fluid.
Equipped with
If the first fluid is not heated,
The gap between the tip of the protrusion and the inner surface of the inner pipe is larger on the outlet side of the first fluid than on the inlet side of the first fluid.
If the first fluid is heated,
The gap between the tip of the protrusion and the inner surface of the inner tube is small over the entire flow path of the first fluid.
A heat exchanger characterized by that. The heat exchanger according to claim 1, wherein the outer diameter of the shaft portion is smaller on the outlet side of the first fluid than on the inlet side of the first fluid. The heat exchanger according to claim 1 or 2, wherein the linear expansion coefficient of the material forming the insert is larger than the linear expansion coefficient of the material forming the inner tube. The heat according to any one of claims 1 to 3, wherein an outer tube through which a second fluid flows is provided on the outer surface of the inner tube, and the first fluid is heated by the second fluid. Exchanger. The heat pump water heater provided with the heat exchanger according to claim 4, wherein the first fluid is water and the second fluid is a refrigerant.

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