JPWO2008029639A1 - Corrugated heat transfer tube for hot water supply - Google Patents

Abstract

The present invention relates to a corrugated heat transfer tube for hot water supply that performs heat exchange between the inside and the outside. A plurality of protrusions having a height H1 of 0.5 mm to 1.5 mm are provided on at least a part of the inner surface of the portion located in a section where the Reynolds number (Re) of the fluid flowing inside the corrugated heat transfer tube is less than 7000, The height H1 of the protrusion is 0.05 to 0.15 times the inner diameter D, or the height H1 of the protrusion is 1 to 3 times the depth (Hm) of the corrugated groove. As a result, the heat transfer performance is improved in a low Reynolds number region with a simple structure, and the pressure loss in the pipe is small.

Description

  The present invention relates to hot water heater technology, and more particularly to a hot water corrugated heat transfer tube having a Reynolds number Re of a fluid flowing in the tube of less than 7000.

In a heat exchange device used for an air conditioner, a water heater, or the like, a heat transfer tube is provided in which a fluid such as water flows in the tube and heat exchange is performed by a temperature difference between the inside and outside of the tube. In order to improve the heat transfer performance of the heat transfer tube, a grooved tube having a groove formed on the inner surface of the tube may be used. In addition, a technique for improving the heat transfer performance by providing a protrusion on the inner surface of the heat transfer tube has been proposed.
As described above, when the protrusion is provided inside the heat transfer tube, the heat transfer area of the heat transfer tube is increased, and the fluid is agitated by the protrusion, thereby increasing the heat transfer rate on the heat transfer surface and improving the heat transfer performance. To do. However, if a protrusion is provided inside the heat transfer tube, the protrusion increases the coefficient of friction of the tube and increases the pressure loss of the flow in the tube. Thus, a technique has been proposed in which a protrusion having a height of 0.45 mm to 0.6 mm is provided inside the heat transfer tube to suppress pressure loss while promoting heat transfer with the refrigerant (Patent Document 1). Moreover, the technique which aims at the improvement of heat-transfer capability by employ | adopting a corrugated pipe as a heat-transfer pipe is proposed (patent document 2).
JP 6-70556 JP 2002-228370 A

However, when the flow velocity of the fluid in the heat transfer tube is very low and the fluid flow in the tube is a transition region from the laminar flow region to the turbulent flow region, the height of 0.45 mm to 0.6 mm disclosed in Patent Document 1 Even if the protrusion is provided, the improvement in heat transfer performance is small.
For example, in the heat pump type water heater shown in FIG. 1, water is boiled in a transient manner from about 10 ° C. to about 90 ° C. over a long period of time in order to efficiently use night electricity with a low electricity bill. Here, in order to ensure compactness and high efficiency of the product, the flow rate of water flowing in the heat transfer tube is set to a very small value (for example, 0.8 L / min). Thus, in the heat transfer tube with a small water flow rate in the tube, a method of increasing the flow rate in the tube and reducing the heat transfer performance by reducing the inner diameter of the heat transfer tube is adopted. However, even in this case, since the water flow rate in the pipe is small, the flow of water in the pipe is the transition region from the laminar flow region to the turbulent flow region (Re = 1500 to 3000) near the inlet, and the initial turbulent flow (Re = 7000). In addition, in the low temperature section near the water inlet, the heat conductivity is small, so that efficient heat exchange cannot be expected.

Further, when the flow velocity of the fluid in the heat transfer tube is very low and the flow of the fluid in the tube is a transition region from the laminar flow region to the turbulent flow region, the improvement in heat transfer performance by the corrugated tube alone is small. Further, since the corrugated tube generates strong turbulent flow at the boundary of the tube wall, depending on the depth of the corrugated groove, the tube friction coefficient is considerably increased as compared with the smooth tube, and the pressure loss of the flow in the tube is increased.
An object of the present invention is to provide a corrugated heat transfer tube for hot water supply that overcomes the problems of the background art described above, has a simple structure, improves heat transfer performance in a low Reynolds number region, and has low pressure loss in the tube. It is in.

The corrugated heat transfer tube for hot water supply according to the first invention is a hot water corrugated heat transfer tube for exchanging heat between the inside and the outside, and is provided on the inner surface of the portion located in a section where the Reynolds number Re of the fluid flowing inside is less than 7000 A plurality of protrusions having a height H1 of 0.5 mm to 1.5 mm are provided at least partially.
When a corrugated tube is employed as the heat transfer tube, a turbulent flow is generated by the corrugated groove, and an effect of improving the heat transfer performance can be obtained. On the other hand, in the low Reynolds number section where the transition from the laminar flow region and the laminar flow region to the turbulent flow region occurs, it is necessary to increase the depth of the corrugated groove in order to obtain the effect of improving the heat transfer performance using only the corrugated tube. This increases the coefficient of friction of the tube and increases the pressure loss in the tube.
Therefore, the height protruding toward the inside of the pipe is 0. 0 on the inner surface of the laminar flow area and the low Reynolds number section where the transition from the laminar flow area to the turbulent flow area occurs, that is, the section where the Reynolds number Re is less than 7000. A plurality of protrusions of 5 mm to 1.5 mm were provided. As a result, the heat transfer coefficient is improved by the corrugated pipe and the protrusion provided in the pipe, the depth of the corrugated groove is suppressed, and the influence of the protrusion on the pressure loss in the pipe is small. Performance is improved.

A hot water corrugated heat transfer tube according to the second aspect of the present invention is a hot water corrugated heat transfer tube that exchanges heat between the inside and the outside, and is provided on the inner surface of a portion located in a section where the Reynolds number Re of the fluid flowing inside is less than 7000. A plurality of protrusions whose height H1 is 0.05 to 0.15 times the inner diameter D are provided at least in part.
When protrusions are provided in the pipe, the pipe friction coefficient is a function of the Reynolds number Re and the relative roughness. Here, in order to express the influence of the projections in the pipe on the pipe friction coefficient, the ratio between the height of the projection provided in the pipe and the inner diameter of the pipe (that is, relative roughness) is used. In a section with a low Reynolds number where a transition from a laminar flow region to a turbulent flow region occurs, the relative roughness of the inner wall surface of the pipe is kept within a specified range, thereby improving the heat transfer effect and minimizing the effect of pressure loss. be able to.
Therefore, on the inner surface of the laminar flow area and the low Reynolds number section where the transition from the laminar flow area to the turbulent flow area occurs, that is, in the section where the Reynolds number Re is less than 7000, the height H1 is 0.05 to A plurality of projections having a size of 0.15 were provided. As a result, the heat transfer rate is improved by the protrusion provided in the pipe, and the influence of the protrusion on the pressure loss in the pipe is suppressed, and the performance of the entire hot water corrugated heat transfer pipe is improved.

A hot water corrugated heat transfer tube according to a third aspect of the present invention is a heat transfer tube that is used in a hot water heat exchanger and performs heat exchange between the inside and the outside, and the Reynolds number (Re) of the fluid flowing inside is less than 7000. A plurality of protrusions whose height (H1) is 1 to 3 times the depth (Hm) of the corrugated groove are provided on at least a part of the inner surface of the portion located in the section.
When a protrusion is provided in the heat transfer tube provided with the corrugated groove, the heat transfer effect is improved by the height (H1) of the protrusion and the depth (Hm) of the corrugated groove and the influence of pressure loss is minimized. It is necessary to suppress. When the Reynolds number (Re) is less than 7000 and the height (H1) of the plurality of protrusions is 1 to 3 times the depth (Hm) of the corrugated groove, the corrugated tube and the tube are provided. The heat transfer coefficient can be improved by the protrusion, the depth of the corrugated groove can be suppressed, and the influence of the protrusion on the pressure loss in the pipe can be reduced, and the performance of the entire corrugated heat transfer pipe for hot water supply can be improved.

A hot water corrugated heat transfer tube according to a fourth aspect of the present invention is a heat transfer tube that is used in a hot water heat exchanger and performs heat exchange between the inside and the outside, and the Reynolds number (Re) of the fluid flowing inside is less than 7000. A plurality of protrusions are provided on at least a part of the inner surface of the portion located in the section,
The pitch (P1) of the plurality of protrusions and the pitch (Pm) of the corrugation are different values.
When the protrusion and the corrugated groove are provided at the overlapping position, the coefficient of friction in the pipe increases, and the pressure loss in the pipe may increase rapidly. Here, by setting the pitch (P1) of the projection and the pitch (Pm) of the corrugation to be different from each other, the projection is provided at a position where it does not overlap with the corrugated groove, and a rapid increase in pressure loss in the pipe can be suppressed. .

A corrugated heat transfer tube for hot water supply according to a fifth aspect of the present invention is a heat transfer tube that is used in a heat exchanger for hot water supply and performs heat exchange between the inside and the outside, in the vicinity of an inlet into which water that is a fluid flowing inside flows A plurality of protrusions having a height H1 of 0.5 mm to 1.5 mm are provided on the inner surface of the portion located at.
The flow of water near the inlet of the heat transfer tube used in the heat exchanger for hot water supply corresponds to a laminar flow region and / or a transition region from a laminar flow region to a turbulent flow region. On the other hand, near the inlet of the heat transfer tube, the water temperature is low and the heat transfer coefficient is also low. Therefore, in the present invention, a plurality of protrusions having a height of 0.5 mm to 1.5 mm are provided at least on the inner surface of the portion located in the vicinity of the water inlet, and the heat transfer coefficient is improved by the protrusions provided in the pipe. I am trying. Further, the heat transfer coefficient is improved by the protrusions, and the influence of the protrusions on the pressure loss in the pipe is small, so that the performance of the hot water corrugated heat transfer pipe as a whole is improved.

A corrugated heat transfer tube for hot water supply according to a sixth aspect of the present invention is a heat transfer tube used for a heat exchanger for hot water supply to exchange heat between the inside and the outside, and is a fluid inlet into which water, which is a fluid flowing inside, flows. A plurality of protrusions whose height H1 is 0.05 to 0.15 times the inner diameter D are provided on the inner surface of the portion located in the vicinity.
In the hot water supply heat exchanger, the flow of water near the inlet of the heat transfer tube corresponds to a laminar flow region and / or a transition region from a laminar flow region to a turbulent flow region. In addition, the water temperature is low near the inlet of the heat transfer tube, and the heat transfer coefficient is also low. Therefore, in this heat exchanger for hot water supply, a plurality of protrusions whose height is 0.05 to 0.15 times the inner diameter of the heat transfer tube are provided at least on the inner surface of the heat transfer tube located in the vicinity of the water inlet. As a result, the heat transfer rate is improved by the protrusion provided in the pipe, and the influence of the protrusion on the pressure loss in the pipe is suppressed, and the performance of the entire hot water corrugated heat transfer pipe is improved.

A corrugated heat transfer tube for hot water supply according to a seventh aspect of the present invention is a heat transfer tube that is used in a heat exchanger for hot water supply and performs heat exchange between the inside and the outside, in the vicinity of a fluid inlet into which water that is a fluid flowing inside flows A plurality of protrusions whose height (H1) is 1 to 3 times the depth (Hm) of the corrugated groove are provided on the inner surface of the portion located at.
The flow of water near the inlet of the heat transfer tube corresponds to a laminar flow region and / or a transition region from a laminar flow region to a turbulent flow region. In addition, the water temperature is low near the inlet of the heat transfer tube, and the heat transfer coefficient is also low. Here, a protrusion is provided in the heat transfer tube provided with the corrugated groove to improve the heat transfer rate. However, when the protrusion is provided in the heat transfer tube provided with the corrugated groove, the heat transfer effect is improved by the height (H1) of the protrusion and the depth (Hm) of the corrugated groove and the influence of pressure loss is minimized. It is necessary to limit to the limit. When the Reynolds number (Re) is less than 7000 and the height (H1) of the plurality of protrusions is 1 to 3 times the depth (Hm) of the corrugated groove, the corrugated tube and the tube are provided. The heat transfer coefficient can be improved by the protrusion, the depth of the corrugated groove can be suppressed, and the influence of the protrusion on the pressure loss in the pipe can be reduced, and the performance of the entire corrugated heat transfer pipe for hot water supply can be improved.

A hot water corrugated heat transfer tube according to an eighth aspect of the present invention is a heat transfer tube that is used in a heat exchanger for hot water supply and performs heat exchange between the inside and the outside, in the vicinity of an inlet into which water, which is a fluid flowing inside, flows. A plurality of protrusions are provided on the inner surface of the portion located at, and the pitch (P1) of the plurality of protrusions is different from the pitch (P2) of the corrugation.
The flow of water near the inlet of the heat transfer tube corresponds to a laminar flow region and / or a transition region from a laminar flow region to a turbulent flow region. In addition, the water temperature is low near the inlet of the heat transfer tube, and the heat transfer coefficient is also low. Here, a protrusion is provided in the heat transfer tube provided with the corrugated groove to improve the heat transfer rate. However, if the protrusion and the corrugated groove are provided at a position where they overlap, the coefficient of friction in the pipe increases, and the pressure loss in the pipe may increase rapidly. Therefore, by setting the pitch (P1) of the projections and the pitch (P2) of the corrugations to be different values, the projections are provided at positions where they do not overlap with the corrugated grooves, and a rapid increase in pressure loss in the pipe can be suppressed.

  A corrugated heat transfer tube for hot water supply according to a ninth aspect of the invention is the corrugated heat transfer tube for hot water supply according to any one of the first to eighth aspects of the invention, wherein the flow velocity of the fluid flowing inside is 0.1 m / s to 0.6 m / s. It is. In addition, it is preferable that the flow velocity of the fluid which flows through the inside of the corrugated heat transfer tube for hot water supply is 0.2 m / s to 0.4 m / s. Here, when the flow velocity of the fluid in the pipe is less than 0.1 m / s, the heat transfer coefficient of the corrugated heat transfer pipe is extremely low. On the other hand, when the flow velocity of the fluid in the pipe exceeds 0.6 m / s, the friction coefficient in the corrugated pipe increases and the pressure loss in the pipe increases. Therefore, the flow velocity range of the fluid flowing inside is set to 0.1 m / s to 0.6 m / s. As a result, the heat transfer coefficient is improved by the corrugated groove and the protrusion provided in the pipe, and the influence of the protrusion on the pressure loss in the pipe is suppressed, so that the performance of the hot water corrugated heat transfer pipe as a whole is improved.

A corrugated heat transfer tube for hot water supply according to a tenth aspect of the present invention is the corrugated heat transfer tube for hot water supply according to any one of the first to eighth aspects, wherein the cross-sectional shape at an arbitrary height of the protrusion is circular, elliptical or approximate circular It consists of a smooth curve like
Factors affecting the pressure loss of the fluid in the pipe due to the corrugated pipe protrusion include the height of the corrugated groove, the Reynolds number of the fluid in the pipe, the speed, the height of the protrusion, and the shape of the protrusion. When the shape of the protrusion is an acute angle, a separation vortex is generated by the flow that turns the corner, and the pressure loss of the fluid increases.
Therefore, the cross-sectional shape at an arbitrary height of the protrusion is configured by a smooth curve such as a circle, an ellipse, or an approximate circle. That is, since the outer peripheral surface of the projection is formed with a smooth curved surface, the generation of the separation vortex can be suppressed as compared with the projection having an acute shape, and the influence of the pressure loss of the fluid in the pipe can be suppressed, The performance of the entire corrugated heat transfer tube is improved.

A corrugated heat transfer tube for hot water supply according to an eleventh aspect of the present invention is the corrugated heat transfer tube for hot water supply according to any one of the first to eighth aspects of the present invention, wherein a protrusion is formed in a section located near the fluid outlet where the fluid flows out. Not provided.
At the fluid outlet of the corrugated heat transfer tube, the temperature of the fluid is high. For example, when the fluid is water, there is a possibility that the scale adheres to the inner surface of the corrugated tube. If a projection is provided in such a section, there is a possibility that adhesion of the scale is promoted by the projection. Therefore, in a section located near the fluid outlet where the temperature of the fluid is high, generation of scale is suppressed by using a pipe having no protrusion, for example, a smooth pipe.

A corrugated heat transfer tube for hot water supply according to a twelfth aspect of the present invention is the corrugated heat transfer tube for hot water supply according to any of the first to eighth aspects, wherein a groove having a groove depth shallower than the height H1 of the protrusion is formed on the inner surface of the tube. Has been.
In the low Reynolds number region, among the protrusions provided on the inner surface of the corrugated heat transfer tube, the protrusion larger than the small protrusion contributes to the improvement of the heat transfer coefficient. Therefore, the heat transfer effect is improved by providing a protrusion higher than the groove depth of the grooved tube in the corrugated heat transfer tube. On the other hand, in the high Reynolds number region, the shallower groove than the protrusion height contributes to the improvement of the heat transfer coefficient. Therefore, in the high Reynolds region, the heat transfer performance of the corrugated heat transfer tube is further improved by employing a grooved tube in which a groove having a groove depth shallower than the height of the protrusion is formed on the inner surface.

A corrugated heat transfer tube for hot water supply according to a thirteenth aspect of the present invention is the corrugated heat transfer tube for hot water supply according to any one of the first to eighth aspects of the present invention, wherein the plurality of protrusions are provided in parallel to the tube axis direction.
By providing protrusions in the tube axis direction, heat transfer can be continuously promoted. Further, since the fluid flow linearly flows in the tube axis direction, the increase in pressure loss is small, and the performance of the entire heat transfer tube is improved.

A corrugated heat transfer tube for hot water supply according to a fourteenth aspect of the present invention is the corrugated heat transfer tube for hot water supply according to any one of the first to eighth aspects, wherein the plurality of protrusions are provided in a spiral shape.
By providing the protrusions in a spiral shape, swirling occurs in the flow of the fluid in the pipe, the passage length of the fluid is increased, and the heat transfer performance is further improved.

A corrugated heat transfer tube for hot water supply according to a fifteenth aspect of the present invention is the corrugated heat transfer tube for hot water supply according to any one of the first to eighth aspects of the invention, wherein the plurality of protrusions are paired at positions facing each other in the radial direction of the heat transfer tube. It is provided as follows.
By providing the protrusions so as to form a pair at opposite positions in the radial direction, the cross-sectional area in the vicinity of the protrusions is reduced, fluid mixing is promoted, and heat transfer performance is further improved.

A hot water corrugated heat transfer tube according to a sixteenth aspect of the present invention is the hot water corrugated heat transfer tube according to any one of the first to eighth aspects, wherein the ratio of the pitch P1 of the plurality of protrusions to the heat transfer tube inner diameter D is 0.5. -10.
When the ratio between the pitch P1 of the protrusions and the inner diameter D of the heat transfer tube is 0.5 or less, a heat transfer promotion effect can be obtained, but pressure loss increases due to the protrusions on the upstream side. Further, when the ratio between the pitch P1 of the protrusions and the heat transfer tube inner diameter D is 10 or more, the heat transfer promotion effect is reduced.
Therefore, by setting the ratio of the pitch P1 of the protrusions to the heat transfer tube inner diameter D to be 0.5 to 10, while maintaining the heat transfer promotion effect, the increase in pressure loss is small and the performance of the entire heat transfer tube is improved.

A hot water corrugated heat transfer tube according to a seventeenth aspect of the present invention is the hot water corrugated heat transfer tube according to any one of the first to eighth aspects of the invention, wherein the height (H2) is less than 0.5 mm between the plurality of protrusions. Small protrusions are provided.
In the low Reynolds number region, the protrusion larger than the small protrusion contributes to the improvement of the heat transfer coefficient. However, in the high Reynolds number area, the protrusion smaller than the large protrusion (small protrusion) improves the heat transfer coefficient. To contribute. Here, by providing small protrusions between large protrusions, heat transfer performance is improved by large protrusions in sections where the Reynolds number is low, and in a section where the Reynolds number is high, there is a synergistic effect of improving heat transfer performance by small protrusions. As a result, the performance of the entire heat exchanger is improved.

A corrugated heat transfer tube for hot water supply according to an eighteenth aspect of the present invention is the corrugated heat transfer tube for hot water supply according to any one of the first to eighth aspects of the present invention, wherein a smooth portion having no protrusions is present on the inner surface of the heat transfer tube. .
In the smooth part having no protrusion, the cross-sectional area in the heat transfer tube is maximized. That is, the change in the inner surface shape between the portion where the protrusion is provided and the portion where the protrusion is not provided is maximized, and the heat transfer performance is improved. On the other hand, when there is no smooth portion on the inner surface of the heat transfer tube, the effect is the same as that in which the inner diameter of the heat transfer tube is reduced, and the fluid flow rate is increased, and the heat transfer acceleration effect is obtained, but the pressure loss in the tube also increases. .

A corrugated heat transfer tube for hot water supply according to a nineteenth aspect of the present invention is the corrugated heat transfer tube for hot water supply according to any one of the first to eighth aspects of the present invention, wherein the protrusion is formed by applying a force from the outside, and the straight portion Is not formed in the bent portion.
When a protrusion is formed on the inner surface of the heat transfer tube by applying a force from the outside, the outer surface is often recessed and a protrusion is formed on the corresponding inner surface toward the tube. In general, the heat transfer tube has a straight portion and a bent portion. In addition to the pressure loss at the straight portion, the bending portion has an additional pressure loss due to bending. Here, if a protrusion is further provided on the inner surface of the bent portion, the pressure loss at the bent portion may be further increased. In addition, a large deformation may occur in the recessed portion of the outer surface of the heat transfer tube during the bending work process, which may cause damage. Therefore, a protrusion is provided on the straight portion, and no protrusion is provided on the bent portion.

A corrugated heat transfer tube for hot water supply according to a twentieth aspect of the present invention is the corrugated heat transfer tube for hot water supply according to any one of the first to eighth aspects of the present invention, wherein the protrusion is formed by applying a force from the outside, and the bent portion Is not formed in the section intersecting with the bent surface.
In the bent portion of the heat transfer tube, the amount of deformation at the portion intersecting the bent surface is the largest. Therefore, no protrusion is provided in a section intersecting the bent surface in the bent portion of the heat transfer tube. For example, when the heat transfer tube is bent in a horizontal plane, no protrusion is provided in a section that intersects the horizontal plane in the bent portion.

A corrugated heat transfer tube for hot water supply according to a twenty-first invention is the corrugated heat transfer tube for hot water supply according to any one of the first to eighth inventions, wherein a second fluid for supplying a second fluid for supplying heat to the fluid flows to the outside. The heat transfer tube is arranged, the second heat transfer tube is in contact with the outer surface, and the protrusion is formed on the inner surface by denting the outer surface, and the place other than the contact portion with the second heat transfer tube Is formed.
Here, since the protrusion is formed on the inner surface by denting the outer surface, the outer surface corresponding to the portion where the protrusion is formed on the inner surface is formed with a recess. A protrusion is formed in a portion that contacts the second heat transfer tube. That is, when a dent is formed in the outer surface, the contact between the heat transfer tube and the second heat transfer tube is deteriorated, and the heat transfer effect from the second heat transfer tube is reduced. Therefore, by not providing a protrusion in the contact section with the second heat transfer tube, it is possible to prevent a decrease in the heat transfer effect from the second heat transfer tube.

Schematic diagram of heat pump water heater Schematic of a water heat exchanger. The top view of a corrugated heat exchanger tube. The graph showing the Reynolds number of the pipe | tube flow of a corrugated heat exchanger tube. (A) The cross-sectional perspective view of a corrugated heat exchanger tube.

(B) AA arrow sectional drawing of Fig.5 (a).
(C) BB arrow sectional drawing of FIG.5 (b).
The graph which shows the result of the experiment 1. FIG. The graph which shows the result of the experiment 2. FIG. The graph which shows the result of the experiment 3. FIG. The graph of the result of Experiment 4. The top view of the corrugated heat exchanger tube which concerns on Example 1. FIG. The top view of the corrugated heat exchanger tube which concerns on Example 2. FIG. (A) The top view of the corrugated heat exchanger tube which concerns on Example 3. FIG.

(B) The perspective view of the corrugated heat exchanger tube which concerns on Example 3. FIG.
The top view of the corrugated heat exchanger tube which concerns on Example 4. FIG. The top view of the corrugated heat exchanger tube which concerns on Example 5. FIG. (A) The top view of the corrugated heat exchanger tube which concerns on Example 5. FIG. (B) The perspective view of the corrugated heat exchanger tube which concerns on Example 5. FIG. The top view of the corrugated heat exchanger tube which concerns on Example 6. FIG. The top view of the corrugated heat exchanger tube which concerns on Example 7. FIG. The top view of the corrugated heat exchanger tube which concerns on Example 8. FIG. The top view of the corrugated heat exchanger tube which concerns on Example 9. FIG. (A) The top view of the corrugated heat exchanger tube which concerns on Example 10. FIG.

(B) The perspective view of the corrugated heat exchanger tube which concerns on Example 10. FIG.
The top view of the corrugated heat exchanger tube which concerns on Example 11. FIG. (A) The perspective view of a corrugated heat exchanger tube. (B) The perspective view of a high fin heat exchanger tube. (C) Perspective view of a floral pattern heat transfer tube.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hot water storage unit 100 Heat pump water heater 2 Heat pump unit 30 Water heat exchanger 311 Water inlet 312 Water outlet 313,413,513,613 Projection 315 Small protrusion 316,416,516,616 Corrugated groove 644 Groove

A hot water corrugated heat transfer tube according to the present invention will be described with reference to the accompanying drawings and examples.
FIG. 1 is a schematic diagram of a heat pump type hot water heater employing the hot water corrugated heat transfer tube of the present invention. Here, the heat pump water heater includes a hot water storage unit 1 and a heat pump unit 2. The hot water storage unit 1 includes a water pipe 11, a hot water storage tank 12, a water circulation pump 13, a water supply pipe 3, a corrugated heat transfer pipe 31 constituting the water heat exchanger 30, a hot water pipe 16, a mixing valve 17, The hot water supply pipe 18 is connected in order. Here, tap water is supplied from the water supply pipe 11 to the hot water storage tank 12. Water having a low temperature is supplied from the bottom of the hot water storage tank 12 to the corrugated heat transfer pipe 31 of the water heat exchanger 30 from the water circulation pump 13 and heated. The heated hot water flows into the upper part of the hot water storage tank 12. Hot hot water discharged from the upper part of the hot water storage tank 12 through the hot water pipe 16 is mixed with cold water in the mixed water pipe 19 by the mixing valve 17. The temperature of the hot water supply is adjusted by the mixing valve 17 and supplied to the user through the hot water supply pipe 18.

Next, the heat pump unit 2 includes a refrigerant circulation circuit, and the refrigerant circulation circuit connects the compressor 21, the water heat exchanger 30, the expansion valve 23, and the air heat exchanger 24 through the refrigerant pipe 32 in order. Configured. The refrigerant is compressed to a high pressure by the compressor 21 and then sent to the water heat exchanger 30. The refrigerant heat-exchanged in the water heat exchanger 30 passes through the expansion valve 23 and is supplied to the air heat exchanger 24. The refrigerant absorbs heat from the surroundings and is returned to the compressor 21.
FIG. 2 is a schematic view of the water heat exchanger 30 in the heat pump water heater. As shown in FIG. 2, the water heat exchanger 30 includes a corrugated heat transfer tube 31 and a refrigerant tube 32. The corrugated heat transfer tube 31 is formed in a spiral shape so as to have an oval shape on the same plane, and forms a water passage W. The refrigerant tube 32 is spirally wound around the outer periphery of the heat transfer tube 31 to form a refrigerant passage R. The outer periphery of the spiral in the corrugated heat transfer tube 31 is the water inlet 311, and the center of the spiral in the corrugated heat transfer tube 31 is the water outlet 312. In the water heat exchanger 30, the refrigerant in the refrigerant pipe 32 flows in from the A22 direction at the refrigerant inlet 322 and radiates heat. Thereafter, the refrigerant flows out from the A21 direction at the refrigerant outlet 321. The tap water supplied from the A11 direction at the water inflow port 311 is heated by this heat, becomes hot water, and flows out in the A12 direction at the water outlet 312.

Next, the corrugated heat transfer tube 31 will be described. As shown in FIG. 3, a corrugate 316 is formed on the inner surface of the corrugated heat transfer tube 31, and a plurality of protrusions 313 having a height of H1 are provided vertically symmetrically in the tube axis direction. In FIG. 3, only the protrusions 313 provided above as viewed from the paper surface direction are displayed. In this embodiment, the water temperature at the water inlet 311 of the heat transfer tube 31 is set to about 10 ° C., and the water temperature at the water outlet 312 is set to about 90 ° C. Here, the flow rate of water in the corrugated heat transfer tube is about 0.8 L / min. Moreover, it is preferable that the outer diameter of a corrugated heat exchanger tube is 8 mm-14 mm (inner diameter is 6 mm-12 mm).
The Reynolds number Re of the in-pipe flow of the corrugated heat transfer tube 31 is shown in FIG. As shown in FIG. 4, the Reynolds number Re at the water inlet 311 of the corrugated heat transfer tube 31 is about 2000, and the flow in the tube is a laminar flow region. As the water flow proceeds, the water flowing in from the inlet 311 exchanges heat with the refrigerant pipe 32 shown in FIG. As the water temperature rises, the viscosity coefficient of water decreases and the Reynolds number Re increases gradually. In FIG. 4, the Reynolds number Re at the water outlet 312 is about 7000, and the pipe flow is located in the transition region from laminar flow to turbulent flow. Here, the following experiment was conducted in order to investigate the influence of the plurality of protrusions 313 provided on the inner surface of the corrugated heat transfer tube 31 on the heat transfer performance and the pressure loss.

(1) Experiment 1
FIG. 5A is a cross-sectional perspective view of the corrugated heat transfer tube 31. In Experiment 1, a corrugation 316 having a depth of Hm and a protrusion having a height of H1 are provided vertically symmetrically on the inner surface of a tube having an inner diameter D of 8 mm. 5B is a cross-sectional view taken along the line AA in FIG. 5A, and FIG. 5C is a cross-sectional view taken along the line BB in FIG. 5B. As can be seen from FIGS. 5A and 5B, the protrusion 313 is formed on the inner surface by denting the outer surface of the heat transfer tube. Further, as can be seen from FIG. 5C, the shape of the cross-sectional view of the protrusion 313 is formed to be elliptical. Here, on the inner surface of the corrugated heat transfer tube 31, there is a flat portion 31a on which no protrusion is provided.
FIG. 6 (a) shows a case where a corrugated pipe without projections is adopted in each Reynolds number Re in a low Reynolds number section where the flow in the pipe undergoes a transition from a laminar flow region and a laminar flow region to a turbulent flow region. This shows the heat transfer performance when the corrugation depth Hm + projection height H1 is 1.2 mm. Here, the horizontal axis represents the value of the Reynolds number Re. The vertical axis represents the ratio (Nu / Nuo) between the Nusselt number Nu of the corrugated heat transfer tube with the protrusion 313 and the corrugated heat transfer tube without the protrusion and the smooth tube Nuo. Here, the Nusselt number is a dimensionless heat transfer coefficient value as an index of heat transfer from the solid wall to the fluid. The larger the value, the easier the heat is transferred from the solid wall to the fluid. Become. Therefore, the larger the value of Nu / Nuo, the greater the improvement in the heat transfer performance of the heat transfer tube by the protrusions and corrugates. The solid line represents the experimental result when the corrugated heat transfer tube provided with the protrusion 313 and the dotted line represents the corrugated heat transfer tube without the protrusion. As can be seen from FIG. 6 (a), the heat transfer performance of the corrugated heat transfer tube provided with no protrusion is about three times that of the smooth tube regardless of the Reynolds number. On the other hand, in the case of a corrugated heat transfer tube provided with a protrusion 313 having a protrusion height H1 of 1.2 mm, the heat transfer performance is clearly improved by the protrusion 313 provided in the tube when the Reynolds number Re is 4000 or less. On the other hand, when the Reynolds number Re is 4000 or more, the improvement in heat transfer performance by the protrusions 313 provided in the pipe is moderate.

  FIG. 6 (b) shows a case where a corrugated pipe without projections is employed in each Reynolds number Re in a laminar flow region and a low Reynolds number section where a transition from a laminar flow region to a turbulent flow region occurs. 6 shows the transition of the pressure loss in the tube when the corrugated heat transfer tube 31 is employed when the corrugation depth Hm + the projection height H1 is 1.2 mm. Here, the horizontal axis represents the value of the Reynolds number Re. The vertical axis represents the ratio (f / fo) between the fanning friction coefficient f of the corrugated heat transfer tube provided with the protrusion 313 and the corrugated pipe not provided with the protrusion and the fanning friction coefficient fo of the smooth tube. Here, the friction coefficient of fanning is a dimensionless number representing the pressure loss of the pipe flow, and the larger the value, the larger the pressure loss of the pipe flow. Therefore, the greater the value of f / fo, the greater the water pressure loss in the pipe. The solid line represents the experimental result when the corrugated heat transfer tube provided with the protrusion 313 and the dotted line represents the corrugated heat transfer tube without the protrusion. As can be seen from FIG. 6B, when the Reynolds number Re is 7000 or less, the increased portion of the in-tube pressure loss due to the protrusion 313 provided on the inner surface of the tube is substantially constant.

(2) Experiment 2
In Experiment 2, in order to investigate the effect of the height H1 of the protrusion 313 on the heat transfer performance and the pressure loss of the flow in the pipe, the experiment was performed while changing the height H1 of the protrusion 313 provided on the inner surface of the pipe. FIG. 7A shows the heat transfer performance when a corrugated heat transfer tube having an inner diameter D of 8 mm is provided with protrusions having different heights H1 symmetrically so that the pitch P in the tube axis direction is 15 mm. Is. Here, the horizontal axis represents the value of the height H1 of the protrusion 313. The vertical axis represents the ratio (Nu / Nuo) between the Nusselt number Nu of the corrugated heat transfer tube 31 provided with the projection 313 and the Nusselt number Nuo of the smooth tube not provided with the projection. The solid line represents the experimental result when the Reynolds number Re is 4000, and the dotted line represents the experimental result when the Reynolds number Re is 2000. As can be seen from FIG. 7A, the heat transfer performance improves as the height H1 of the protrusion 313 increases in both cases where the Reynolds number Re is 4000 and 2000.

FIG. 7B shows the transition of the pressure loss in the pipe. Here, the horizontal axis represents the value of the height H1 of the protrusion 313. The vertical axis represents the ratio (f / fo) between the fanning friction coefficient f of the corrugated heat transfer tube 31 provided with the projection 313 and the fanning friction coefficient fo of the smooth tube not provided with the projection. The solid line represents the experimental result when the Reynolds number Re is 4000, and the dotted line represents the experimental result when the Reynolds number Re is 2000. As can be seen from FIG. 7B, in both the Reynolds number Re of 4000 and 2000, the pressure loss in the pipe increases as the height H1 of the protrusion 313 increases. In particular, when H1 is 1.0 or more, the increase in the pressure loss in the tube is remarkable.
FIG. 7C shows the performance of the entire heat transfer tube when the corrugated heat transfer tube having an inner diameter D of 8 mm is provided with protrusions having different heights H1 vertically symmetrical at a pitch of 15 mm (tube axis direction). . That is, it represents performance that comprehensively considers improvement in heat transfer performance and suppression of pressure loss. Here, the horizontal axis represents the height value of the protrusion. The vertical axis represents the ratio (Nu / Nuo) between the Nusselt number Nu of the corrugated heat transfer tube provided with the protrusion and the Nusselt number Nuo of the smooth tube not provided with the protrusion, and the friction coefficient f of the fanning of the heat transfer tube provided with the protrusion. It represents the value divided by the ratio (f / fo) to the friction coefficient fo of the fanning of a smooth tube without projections. As described above, the heat transfer performance is improved as the value of Nu / Nuo is increased, and the water pressure loss in the pipe is increased as the value of f / fo is increased. Therefore, as the value obtained by dividing the Nu / Nuo value by the f / fo value is larger, the heat transfer performance can be improved, and the influence of the protrusion on the pressure loss in the pipe can be suppressed, and the performance of the entire heat transfer pipe is improved. It will be done.

In FIG. 7C, the solid line represents the experimental result when the Reynolds number Re is 4000, and the dotted line represents the experimental result when the Reynolds number Re is 2000. As can be seen from FIG. 7C, when the Reynolds number Re is 2000 and the height of the protrusion provided in the heat transfer tube is 0.79 mm, the value of Nu / Nuo is divided by the value of f / fo. When the height of the protrusion exceeds 2.0 mm, the value is significantly reduced. That is, in the low Reynolds number section, when the height of the protrusion is in the range of 0.5 mm to 1.5 mm, the performance of the entire heat transfer tube can be improved. In particular, the height of the protrusion is preferably in the range of 0.5 mm to 0.79 mm.
(3) Experiment 3
In Experiment 3, the height H1 of the protrusion 313 is not used as an index, but the relative roughness (H1 / D) is used as an index. In order to investigate the influence of this relative roughness (H1 / D) on the heat transfer performance and the pressure loss of the flow in the pipe, an experiment was conducted while changing the relative roughness (H1 / D). FIG. 8A shows the heat transfer performance of the corrugated heat transfer tube when the relative roughness (H1 / D) is different in a state where the Reynolds number Re is 2000 and a state where the Reynolds number Re is 4000. Here, the horizontal axis represents the value of relative roughness (H1 / D). The vertical axis represents the ratio (Nu / Nuo) between the Nusselt number Nu of the corrugated heat transfer tube 31 provided with the projection 313 and the Nusselt number Nuo of the smooth tube not provided with the projection. As can be seen from FIG. 8A, the heat transfer performance improves as the value of the relative roughness (H1 / D) of the protrusion increases. Further, as can be seen from the dotted line in FIG. 8A, in the state where the Reynolds number is 2000, when the value of the relative roughness (H1 / D) is 0.1 or less, the improvement of the heat transfer performance by the protrusion is small.

FIG. 8B shows the transition of the pressure loss in the pipe. Here, the horizontal axis represents the value of relative roughness (H1 / D). The vertical axis represents the ratio (f / fo) between the fanning friction coefficient f of the corrugated heat transfer tube 31 provided with the projection 313 and the fanning friction coefficient fo of the smooth tube not provided with the projection. The solid line represents the experimental result when the Reynolds number Re is 4000, and the dotted line represents the experimental result when the Reynolds number Re is 2000. As can be seen from FIG. 8B, in both the Reynolds number Re of 4000 and 2000, the in-tube pressure loss increases as the height H1 / D of the protrusion 313 increases. In particular, when H1 / D is 0.12 or more, the increase in pressure loss in the tube is remarkable.
FIG. 8C shows the performance of the entire corrugated transmission tube when the relative roughness (H1 / D) of the protrusions is different. Here, the horizontal axis represents the value of relative roughness (H1 / D). The vertical axis shows the ratio (Nu / Nuo) between the Nusselt number Nu of the heat transfer tube provided with the projection and the Nusselt number Nuo of the smooth tube not provided with the projection, and the friction coefficient f of the fanning of the corrugated heat transfer tube provided with the projection. It represents the value divided by the ratio (f / fo) to the friction coefficient fo of the fanning of a smooth tube without projections. As described above, the heat transfer performance is improved as the value of Nu / Nuo is increased, and the water pressure loss in the pipe is increased as the value of f / fo is increased. Therefore, the larger the value obtained by dividing the Nu / Nuo value by the f / fo value, the more the heat transfer coefficient is improved and the influence of the protrusions on the pressure loss in the tube is suppressed, and the performance of the entire corrugated heat transfer tube is improved. It will be done. As can be seen from FIG. 8C, when the Reynolds number Re is 2000, when the relative roughness (H1 / D) of the protrusion provided in the corrugated heat transfer tube is 0.1, the value of Nu / Nuo Is the largest value divided by the value of f / fo, and when the relative roughness (H1 / D) of the protrusion exceeds 0.20, the value becomes remarkably small. That is, in the section of the low Reynolds number Re, when the relative roughness (H1 / D) of the protrusion is in the range of 0.05 to 0.15, the performance of the entire heat transfer tube can be improved. In particular, the relative roughness (H1 / D) of the protrusion is preferably in the range of 0.05 to 0.15.

(4) Experiment 4
In Experiment 4, not only the index of the height H1 of the protrusion 313 but also the ratio (H1 / Hm) between the height H1 of the protrusion 313 and the depth Hm of the corrugated groove is used as an index. In order to investigate the influence of the relative height (H1 / Hm) on the heat transfer performance and the pressure loss of the flow in the pipe, an experiment was conducted while changing the relative height (H1 / Hm). FIG. 9A shows the heat transfer performance when the Reynolds number Re is 2000 and 4000 and the relative heights (H1 / Hm) are different. Here, the horizontal axis represents the value of the relative height (H1 / Hm). The vertical axis represents the ratio (Nu / Nuo) between the Nusselt number Nu of the corrugated heat transfer tube 31 provided with the projection 313 and the Nusselt number Nuo of the smooth tube not provided with the projection. As can be seen from FIG. 9A, the heat transfer performance improves as the value of the relative height (H1 / Hm) of the protrusion increases. Further, as can be seen from the dotted line in FIG. 9A, in the state where the Reynolds number is 2000, when the value of the relative roughness (H1 / Hm) is 0.5 or less, the improvement of the heat transfer performance by the protrusion is small.

FIG. 9B shows the transition of the pressure loss in the pipe. Here, the horizontal axis represents the value of the relative height (H1 / Hm). The vertical axis represents the ratio (f / fo) between the fanning friction coefficient f of the corrugated heat transfer tube 31 provided with the projection 313 and the fanning friction coefficient fo of the smooth tube not provided with the projection. The solid line represents the experimental result when the Reynolds number Re is 4000, and the dotted line represents the experimental result when the Reynolds number Re is 2000. As can be seen from FIG. 8B, when the Reynolds number Re is 2000, the pressure loss in the pipe increases as the height relative height (H1 / Hm) of the protrusion 313 increases. In particular, when H1 / Hm is 1.8 or more, the increase in pressure loss in the tube is remarkable.
FIG. 9C shows the performance of the entire transmission tube when the relative heights (H1 / Hm) of the protrusions are different. Here, the horizontal axis represents the value of the relative height (H1 / Hm). The vertical axis shows the ratio (Nu / Nuo) between the Nusselt number Nu of the heat transfer tube with projections and the Nusselt number Nuo of the smooth tube without projections, and the friction coefficient f of the fanning of the heat transfer tubes with projections and the projections. Represents the value divided by the ratio (f / fo) to the friction coefficient fo of the fanning of the smooth tube not provided with. As can be seen from FIG. 9C, when the Reynolds number Re is 2000 and the relative height (H1 / Hm) of the projection provided in the heat transfer tube is 1.8, the value of Nu / Nuo is f. The value divided by the value of / fo is the largest, and when the relative height (H1 / Hm) of the protrusion exceeds 3.0, the value becomes remarkably small. That is, when the relative height (H1 / Hm) of the protrusions is in the range of 1.0 to 3.0 in the section of the low Reynolds number Re, the performance of the entire heat transfer tube can be improved. In particular, the relative height (H1 / Hm) of the protrusions is preferably in the range of 1.0 to 2.0.

Different structures of the corrugated heat transfer tube for hot water supply according to the present invention will be further described in the following embodiments (inner diameter D, corrugated groove depth Hm, protrusion heights H1, H2, pitch and groove in the following embodiments) The values such as the depth are merely examples, and the numerical ranges of the respective parameters described in the claims in the examples and the values used in the above experiments can also be used.)
<Example 1>
FIG. 10 shows the structure of the corrugated heat transfer tube 41 used in the first embodiment. As shown in FIG. 10A, a corrugated groove 416 having a groove depth Hm of 0.5 mm and a tube axis direction pitch Pm of 10 mm is formed in a smooth tube having an inner diameter D of 8 mm. As shown in FIG. 10B, the protrusions 43 having a height H1 of 1 mm are provided vertically symmetrically so that the pitch P in the tube axis direction is 15 mm. Here, by setting different values for the pitch (P1) of the plurality of protrusions and the pitch (Pm) of the corrugation, the protrusion 413 is provided at a position where it does not overlap the corrugated groove 416, and the pressure loss in the pipe increases rapidly. Can be suppressed.

<Example 2>
In the corrugated heat transfer tube 51 of the second embodiment, as shown in FIG. 11, a corrugated groove 516 is provided, and a height H2 is a small 0.3 mm between the protrusions 513 having a height H1 of 1.0 mm. A protrusion 515 is provided. In the low Reynolds number region, the protrusion larger than the small protrusion contributes to the improvement of the heat transfer coefficient. However, in the high Reynolds number area, the protrusion smaller than the large protrusion contributes to the improvement of the heat transfer coefficient. Therefore, by providing a small protrusion 515 having a height H2 of 0.3 mm between the protrusions 513 having a height H1 of 1.0 mm, the heat transfer performance is improved by the corrugated grooves 516 and the protrusions 513 in a section where the Reynolds number is low. In the section where the Reynolds number is high, the synergistic effect of improving the heat transfer performance by the corrugated grooves 516 and the small protrusions 515 is achieved, thereby improving the performance of the entire heat exchanger.

<Example 3>
As shown in FIG. 12, the corrugated heat transfer tube 61 employed in Example 3 is provided with a protrusion 613 along the spiral C1 on the inner surface of the tube. FIG. 12A is a plan view of the corrugated heat transfer tube 61, and FIG. 12B is a perspective view of the corrugated heat transfer tube 61. Here, the height H1 of the protrusion 613 is 1.0 mm, the pitch P1 in the circumferential direction is 6 mm, and the pitch P2 in the tube axis direction is 6 mm.
<Example 4>
As shown in FIG. 13, the corrugated heat transfer tube 63 employed in Example 4 has a section 63a in which a protrusion 633 is provided in a heat transfer tube in which a corrugated groove 636 having a depth of 0.5 mm is provided, and the protrusion is The section 63b is not provided. Here, the section 63 b where no protrusion is provided is a section located in the vicinity of the water outlet 632. In the vicinity of the outlet 632 of the heat transfer tube 63, the temperature of water, which is a fluid, is high, and there is a possibility that the scale adheres to the tube wall. When a projection is provided in such a section, scale adhesion may be promoted. Therefore, the generation of scale can be suppressed by providing no projections in the section 63b located near the water outlet 632 having a high water temperature.

<Example 5>
As shown in FIG. 14, the corrugated heat transfer tube 64 employed in Example 5 has a height of a grooved tube provided with a corrugated groove 646 having a depth of 0.5 mm and a groove 644 having a depth of 0.2 mm. The protrusions 643 with H1 of 1.0 mm are provided vertically symmetrically so that the pitch P in the tube axis direction is 15 mm. Here, the corrugated groove 646 is represented by a solid line, and the groove 644 is represented by a thin solid line. Here, by providing the protrusion 643 on the pipe in which the groove 644 is provided, the synergistic effect of the entire heat transfer tube by the corrugated groove 646, the groove 644, and the protrusion 643 is measured.
<Example 6>
As shown in FIG. 15, the corrugated heat transfer tube 65 employed in the sixth embodiment is composed of a section 65a and a section 65b. A corrugated heat transfer tube having no protrusion is employed in the section 65b located in the vicinity of the water outlet 652, and a corrugated groove 656 having a depth of 0.5 mm and a groove having a depth of 0.2 mm are used in the other section 65a. The grooved tube provided with 654 is provided with a protrusion 653 having a height of 1.0 mm. The corrugated groove 656 is represented by a solid line, and the groove 654 is represented by a thin solid line. The synergistic effect of the entire heat transfer tube by the corrugated groove 656, the groove 654, and the protrusion 653 is measured, and the generation of scale in the section 65b located near the water outlet 652 where the water temperature is high is suppressed.

<Example 7>
As shown in FIG. 16, the corrugated heat transfer tube 66 employed in the seventh embodiment includes three sections, a section 66a, a section 66b, and a section 66c. In the section 66a from the water inlet 661 to the Reynolds number Re of 4000 in the pipe, the height of the grooved pipe provided with the corrugated groove 666 having a depth of 0.5 mm and the groove 664 having a depth of 0.2 mm is 1. A corrugated pipe with a corrugated groove 666 having a depth of 0.5 mm is used for the section 66c located near the water outlet 662, and a section provided with a 0.0mm projection 663 is used. A corrugated groove having a depth of 0.5 mm and a grooved tube 66b having a depth of 664 of 0.2 mm are employed between them. Here, the corrugated groove 666 is represented by a solid line, and the groove 664 is represented by a thin solid line. Here, in the section where the Reynolds number is low, the heat transfer performance is improved by the protrusion 663, the groove 664, and the corrugated groove 666, and in the section where the Reynolds number is high, the synergistic effect of improving the heat transfer performance by the groove 664 and the corrugated groove 666 is shown. As a result, the performance of the entire heat exchanger is improved. Further, in the section 66c located near the water outlet 662 where the water temperature is high, the generation of scale due to the corrugated groove 666 is suppressed.

<Example 8>
As shown in FIG. 17, the heat transfer tube 67 employed in Example 8 is composed of three sections, a section 67a, a section 67b, and a section 67c. In the section 67a from the water inlet 671 to the Reynolds number Re in the pipe of 4000, a corrugated groove 666 having a depth of 0.5 mm and a protrusion 673 having a height of 1.0 mm are used. A corrugated heat transfer tube having a corrugated groove 676 having a depth of 0.5 mm is adopted for the section 67c located in the vicinity, and a corrugated groove 676 having a depth of 0.5 mm is provided between the section 67a and the section 67c. A grooved tube 67b having a depth of 674 of 0.2 mm is employed. Here, the corrugated groove 676 is represented by a solid line, and the groove 674 is represented by a thin solid line. Here, in the section where the Reynolds number is low, the heat transfer performance is improved by the corrugated groove 676 and the protrusion 673, and in the section where the Reynolds number is high, a synergistic effect of improving the heat transfer performance by the corrugated groove 676 and the groove 674 is achieved. The overall performance of the heat exchanger is improved. Further, in the section 67 c located near the water outlet 672 where the water temperature is high, the generation of scale is suppressed by the corrugated groove 676.

<Example 9>
As shown in FIG. 18, in the corrugated heat transfer tube 68 employed in Example 9, the straight portion 684 is provided with the protrusion 683, but the bent portions B1 to B7 (dotted line portions) are not provided with the protrusion. It is possible to avoid an increase in in-tube pressure loss due to the provision of protrusions on the inner surfaces of the bent portions B1 to B7, and to avoid the occurrence of large deformation and breakage in the bending work process.
<Example 10>
FIG. 19A shows a plan view of the corrugated heat transfer tube 69 employed in Example 10, and FIG. 19B shows a perspective view of the heat transfer tube 69. Here, although the protrusion 693 is provided in the straight part 694, no protrusion is provided in the section 695 intersecting the bent surface S1 in the bent part CC.

<Example 11>
As shown in FIG. 20, the corrugated heat transfer tube 70 employed in Example 11 has no protrusion at the contact portion between the outer surface 71 of the corrugated heat transfer tube and the refrigerant tube 72. If the tube outer surface corresponding to the portion around which the refrigerant tube 72 is wound is provided with a dent, the contact between the refrigerant tube 72 and the heat transfer tube outer surface 71 is deteriorated, and the heat transfer effect from the refrigerant tube 72 may be reduced. Therefore, by providing the protrusion 713 at a portion where the refrigerant pipe 72 is not wound, it is possible to prevent the heat transfer effect from the refrigerant pipe 72 from being lowered.
<Others>
In the experiments and examples described above, as shown in FIG. 21A, the corrugated tube having a corrugated groove as the heat transfer tube is provided with a protrusion. In addition, as shown in FIG.21 (b), the pipe | tube with which the projection was provided in the high fin pipe as a heat exchanger tube, or the pipe | tube with which the protrusion was provided in the flower pattern pipe as shown in FIG.21 (c). It can also be adopted.

Claims (21)

A corrugated heat transfer tube for hot water supply that exchanges heat between the inside and the outside.
A spiral corrugation is provided in the tube,
A plurality of protrusions having a height (H1) of 0.5 mm to 1.5 mm are provided on at least a part of the inner surface of a portion located in a section where the Reynolds number (Re) of the fluid flowing inside is less than 7000. Corrugated heat transfer tube for hot water supply. A corrugated heat transfer tube for hot water supply that exchanges heat between the inside and the outside.
A spiral corrugation is provided in the tube,
A plurality of at least part of the inner surface of the portion located in a section where the Reynolds number (Re) of the fluid flowing inside is less than 7000 is 0.05 to 0.15 times the inner diameter (D). Protrusions are provided,
Corrugated heat transfer tube for hot water supply. A corrugated heat transfer tube for hot water supply that exchanges heat between the inside and the outside.
A spiral corrugation is provided in the tube,
Plural in which the height (H1) is 1 to 3 times the depth (Hm) of the corrugated groove on at least a part of the inner surface of the portion located in the section where the Reynolds number (Re) of the fluid flowing inside is less than 7000 Protrusions are provided,
Corrugated heat transfer tube for hot water supply. A corrugated heat transfer tube for hot water supply that exchanges heat between the inside and the outside.
A spiral corrugation is provided in the tube,
A plurality of protrusions are provided on at least a part of the inner surface of the portion located in a section where the Reynolds number (Re) of the fluid flowing inside is less than 7000,
The pitch (P1) of the plurality of protrusions and the pitch (Pm) of the corrugate are different values.
Corrugated heat transfer tube for hot water supply. A corrugated heat transfer tube that is used in a heat exchanger of a water heater and performs heat exchange between the inside and the outside.
A spiral corrugation is provided in the tube,
A plurality of protrusions having a height (H1) of 0.5 mm to 1.5 mm are provided on the inner surface of a portion located in the vicinity of the inflow port into which water that is a fluid flowing through the inside flows.
Corrugated heat transfer tube for hot water supply. A corrugated heat transfer tube that is used in a heat exchanger of a water heater and performs heat exchange between the inside and the outside.
A spiral corrugation is provided in the tube,
A plurality of protrusions whose height (H1) is 0.05 to 0.15 times the inner diameter (D) are provided on the inner surface of the portion located in the vicinity of the fluid inlet into which water, which is the fluid flowing inside, flows. ing,
Corrugated heat transfer tube for hot water supply. A corrugated heat transfer tube that is used in a heat exchanger of a water heater and performs heat exchange between the inside and the outside.
A spiral corrugation is provided in the tube,
A plurality of protrusions whose height (H1) is 1 to 3 times the depth (Hm) of the corrugated groove are provided on the inner surface of a portion located in the vicinity of the fluid inlet into which water, which is a fluid flowing through the inside, flows. ing,
Corrugated heat transfer tube for hot water supply. A corrugated heat transfer tube that is used in a heat exchanger of a water heater and performs heat exchange between the inside and the outside.
A spiral corrugation is provided in the tube,
A plurality of protrusions are provided on the inner surface of the portion located in the vicinity of the inlet into which water, which is a fluid flowing through the inside, flows,
The pitch (P1) of the plurality of protrusions and the pitch (Pm) of the corrugate are different values.
Corrugated heat transfer tube for hot water supply.   The corrugated heat transfer tube for hot water supply according to any one of claims 1 to 8, wherein the flow velocity of the fluid flowing inside is 0.1 m / s to 0.6 m / s.   The hot water corrugated heat transfer tube according to any one of claims 1 to 8, wherein a cross-sectional shape at an arbitrary height of the protrusion is configured by a smooth curve such as a circle, an ellipse, or an approximate circle. The corrugated heat transfer tube for hot water supply according to any one of claims 1 to 8, wherein a smooth portion not provided with the protrusion is provided on an inner surface of a portion located near a fluid outlet from which the fluid flows out. A groove having a groove depth shallower than the height (H1) of the protrusion is formed on the inner surface.
The corrugated heat transfer tube for hot water supply according to any one of claims 1 to 8. The plurality of protrusions are provided in parallel to the direction of the tube axis.
The corrugated heat transfer tube for hot water supply according to any one of claims 1 to 8. The plurality of protrusions are provided in a spiral shape,
The corrugated heat transfer tube for hot water supply according to any one of claims 1 to 8. The plurality of protrusions are provided so as to be paired at radially opposing positions.
The corrugated heat transfer tube for hot water supply according to any one of claims 1 to 8. The ratio between the pitch (P1) and the inner diameter (D) of the plurality of protrusions is 0.5 to 10.
The corrugated heat transfer tube for hot water supply according to any one of claims 1 to 8. A small protrusion having a height (H2) of less than 0.5 mm is provided between the plurality of protrusions.
The corrugated heat transfer tube for hot water supply according to any one of claims 1 to 8. On the inner surface, there is a smooth portion not provided with the protrusion,
The corrugated heat transfer tube for hot water supply according to any one of claims 1 to 8. The protrusion is formed by applying a force from the outside, the protrusion is formed in a straight portion, and the protrusion is not formed in a bent portion.
The corrugated heat transfer tube for hot water supply according to any one of claims 1 to 8. The protrusion is formed by applying a force from the outside, and in the bent portion, the protrusion is not formed in a portion that intersects the bent surface.
The corrugated heat transfer tube for hot water supply according to any one of claims 1 to 8. A second heat transfer tube for flowing a second fluid that exchanges heat with the fluid is disposed outside the corrugated heat transfer tube for hot water supply,
The second heat transfer tube is in contact with the outer surface of the corrugated heat transfer tube for hot water supply,
The protrusion is formed on the inner surface by denting the outer surface, and is formed at a place other than the contact portion with the second heat transfer tube,
The corrugated heat transfer tube for hot water supply according to any one of claims 1 to 8.

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