Heat-Transfer Device

Abstract

The invention includes a micro porous layer and a plurality of heat-transfer enhancing structures on a surface of the heat transfer tube in contact with the cold fluid. The heat-transfer enhancing structures have a height H that satisfies a relationship to a flow characteristic length D of 0.05>H / D≧0.01, and a relationship to an installation clearance L between the heat-transfer enhancing structures in a flow direction of 40<L / H≦300.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a heat-transfer device.[0003]2. Description of the Related Art[0004]Heat exchangers, which allow two fluids at different temperatures to perform heat exchange, and heaters and coolers of fluids often use convective heat transfer, which is a form of heat transfer that uses heat transportation by flow. In the convective heat transfer, thermal energy is transferred from a heating or cooling surface through a heat conduction layer, a transition layer, and a convection layer to a fluid. The heat conduction layer is a fluid layer formed in a very thin region on the heating or cooling surface. In this layer, heat conduction due to fluid molecular diffusion is dominant rather than the heat transportation by flow. The heat conduction layer has a thickness determined by the Reynolds number Re, which is a dimensionless number representing the ratio of inertial forces to viscous forces in a flow, an...

AI Technical Summary

Benefits of technology

The invention helps to improve heat transfer even at low flow speeds.

Problems solved by technology

This technique, thus, suffers difficulty in obtaining the heat-transfer enhancement effect of the nano-particle porous layer sufficiently due to an increased thickness of the heat conduction layer in a field where the Reynolds number is small, in other words, in a low-velocity flow field (for example, in a range of 0 to 10 m / s).

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