Hot water corrugated heat transfer tube

Abstract

The present invention relates to a hot water corrugated heat transfer tube that exchanges heat between its interior and exterior. A plurality of projections, each whose height (H1) is in the range of 0.5 mm-1.5 mm, is provided in at least one part of the inner surface of a portion positioned in a section of a corrugated heat transfer tube, where the Reynolds number (Re) of the fluid flowing in the interior of the tube is less than 7,000. The height H1 of the projections is in the range of 0.05-0.15 times the inner diameter D or the height H1 of the projections is in the range of 1-3 times the depth (Hm) of the corrugated grooves. As a result, with a simple structure, the heat transfer performance in the low Reynolds number zone is improved, and the pressure loss inside the tube is small.

Description

TECHNICAL FIELD[0001]The present invention relates to hot water heater technology. More specifically, the present invention relates to a hot water corrugated heat transfer tube in which the Reynolds number Re of a fluid flowing inside the tube is less than 7,000.BACKGROUND ART[0002]Heat exchangers used in air conditioners, hot water heaters, and the like, are provided with a heat transfer tube in which a fluid such as water flows and which exchanges heat due to the temperature differential between the tube interior and exterior. Furthermore, to improve the heat transfer performance of the heat transfer tube, a grooved tube in which grooves are formed on the tube inner surface is used in some cases. In addition, a technology has also been proposed which improves the heat transfer performance by providing projections on the inner surface of the heat transfer tube.[0003]Providing projections inside the heat transfer tube in this manner increases the heat transfer surface area of the he...

AI Technical Summary

Benefits of technology

[0010]In addition, when the flow speed of the fluid inside the heat transfer tube is extremely low and the flow of the fluid inside the tube is in the transition zone where the flow transitions from the laminar flow zone to the turbulent flow zone, the improvement in the heat transfer performance simply by means of the corrugated tube is small. Further, since the corrugated tube causes a strong turbulence at the boundary of the tube wall, the friction factor inside the tube increases considerably compared to a smooth tube depending on the depth of the corrugated groove, which consequently increases the pressure loss of the flow inside the tube.

[0056]Here, the projections are formed on the inner surface by depressing the outer surface, and depressions are consequently formed on the outer surface corresponding to the region where the projections are formed on the inner surface. Projections are formed at the portion that contacts the second heat transfer tube. In other words, when depressions are formed on the outer surface, the contact between the heat transfer tube and the second heat transfer tube worsens, thereby reducing the heat transfer effect from the second heat transfer tube. Therefore, by not providing projections in the section of contact with the second heat transfer tube, it is possible to prevent a reduction in the effect of transferring heat from the second heat transfer tube.

Problems solved by technology

In addition, efficient heat exchange cannot be expected because the thermal conductivity is also small in the low temperature section in the vicinity of the water inlet.

Further, since the corrugated tube causes a strong turbulence at the boundary of the tube wall, the friction factor inside the tube increases considerably compared to a smooth tube depending on the depth of the corrugated groove, which consequently increases the pressure loss of the flow inside the tube.

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