Heat Transfer Intensification by Means of Convex-Strip Around Tube in Fin and Tube Heat Exchanger with Field Synergy Principle

Fin and tube is a compact heat exchanger, have been widely used in various engineering fields such as heating, ventilation, air conditioning, and refrigeration systems. An example, indoor and outdoor air-conditioning, the air is used as one of the heat exchanger media. However, over 90% of the total thermal resistance from air to liquid lies on the airside. Therefore, the reduction of thermal resistance should be made to increase heat transfer. This study is intended to investigate the effect of enhancing convex-strip surface to heat transfer and friction characteristic on the heat exchanger. Three-dimensional modeling of the convex fin and the plain fin was conducted on a constant tube temperature of 106℃. Tube with the configuration of the six staggered strands on the odd tube and five rows on the even tube is determined. The velocity variation in the fin gap is assessed under the Reynolds number range between 3,438 to 15,926. The enhancement of four convex-strips around the tube on the fin surface can generate the value of the field synergy angle on fluid flow. The simulation results also show that the improvement of convection heat transfer coefficient value in convex-strip fin with staggered configuration is 15.39% higher than plain-fin.