Experimental investigation into the heat transfer and pressure drop performance of sintered high porosity media

Abstract

• The new type heat transfer tubes have inner diameter 12, 18 mm and dry air heated at 200 °C. • Conventional heat tubes discharged air at approximately 110 °C. • Heat transfer tubes filled with 50 mm of new fibrous porous media discharged air at 2 °C. • The heat transfer performance on the gas side was enhanced. • The new media was organized in terms of friction factor and Reynolds number. There is a method of using porous media to improve the heat transfer performance of the heat tube. However, there are few studies on the fiber structure, which is one of the porous structures. Furthermore, by sintering the heat transfer tube and the porous media, the thermal resistance can be significantly reduced and the heat transfer can be expected to be improved. Therefore, in this study, we experimentally investigated heat transfer and pressure drop in heat transfer tubes made by sintering fibrous porous media. The length of the test section was 150 mm, and dry air heated at 200 °C inside the heat transfer tube and isobutane (R600a) with saturation temperature of 2 °C outside were flowed in the same direction. Tubes sintered with fibrous porous media, compared to the conventional heat transfer tube, the heat transfer coefficient of porous part was up to about 20 times. On the other hand, the pressure drop was about 50 times higher than that of the conventional tube. In addition, the pressure drop per unit length was expressed as a quadratic function of velocity, and the permeability was calculated. By defining the tube friction factor using this permeability, it was confirmed that it can be organized in the same way as porous media with foam structures.