Assessment of heat transfer performance from modified horizontal rectangular heat sink under forced convection dominating mode of mixed convection

Abstract

In the current research, an experimental assessment of heat transfer performance from rectangular fins in the horizontal arrangement has been presented. The specific types of mixed convention i.e. natural (NCDMMC) as well as forced convection dominating mode (FCDMMC) are considered. The parameters encompassed for experimentation are spacing between the fins (S = 2 to 14 mm), flow of air (ReH = 1190 to 2610), input to heater (Q = 25 to 100 W), ratio of width to height of the fin (W/H = 3.0) and, ratio of length to height of the fin (L/H = 5.0) for an array of fins. The outcomes received from the present experimental work are satisfactory and authenticates the FCDMMC. It is observed that alterations in the spacing of the fin, flow velocity considerably influenced the rate of heat transfer from fins. In the case of modified fins under NCDMMC optimum values of average convective coefficient of heat transfer (ha), base convective coefficient of heat transfer (hb) are achieved at wider fin spacing (S) of 10 mm. Whereas optimum magnitudes of ha, hb obtained at compact fin spacing of 6 mm are 30.2, 288.7 W/m2-0C respectively in the case of FCDMMC. The augmentation of about 78.8% in the magnitude of ha is achieved on the compensation of little energy input (0.8 to 1.5 W) to fan as compared to ha in NCDMMC under equivalent conditions. Ineffective areas of fins have been identified with the help of flow virtualization and temperature mapping technique. The central portion of each fin is provided with perforations in the triangular format giving an improvement in the average Nusselt number (Nua) by about 41.2% with respect to the plain fins. The statistical generalized correlations for dimensionless heat transfer coefficient, air flow governing and key geometrical parameters have been developed and presented.