Heat-transfer and friction characteristics for the louver-fin heat exchanger

The present work focuses on the effects of heat-transfer and friction characteristics for the brazed aluminum louver-fin heat exchanger used in a air conditioner with a relatively low air velocity. The heat-transfer and friction characteristics were experimentally studied for the different louver angles and fin pitches of the louver-fin heat exchanger, which are supposed to be the important parameters. Test conditions were varied by four louver angles, three fin pitches, and various Reynolds numbers of air, which ranged from 110 to 800. The experimental results show that the heat transfer is mainly affected by the fin pitch rather than the louver angle, whereas the pressure drop is affected by the louver angle rather than fin pitch. The performance evaluation criterion of heat exchangers is adopted so that the major operational variables, such as heat-transfer coefficient and pumping power, can be considered simultaneously. The j/f(1/3) ratios decrease as the louver angle increases. The optimal value of the j/f(1/3) ratio exists around 20-25 deg of the louver angle. For relatively high louver angles such as 30 and 35 deg, the j/f(1/3) ratios have almost the same value under the condition that the Lp/Fp = 1.03, 1.20, and 1.43.