Heat transfer and pressure drop in a rectangular channel with diamond-shaped elements

Heat transfer and pressure drop experiments were performed for a rectangular channel equipped with arrays of diamond-shaped elements. Both in-line and staggered fin arrays were considered, for values of the longitudinal and transverse spacings, relative to the diamond side, from 4 to 8 and from 4 to 8.5, respectively. The height-to-side ratio of the diamonds was 4.0. Liquid crystal thermography was used to determine the heat transfer coefficients on the surface of the channel (endwall) on which the fins were mounted. Local variations in heat transfer coefficients induced by the arrangements of the diamond-shaped elements were measured and discussed. Correlations giving the average Nusselt number for each fin configuration as a function of the Reynolds number were developed. Thermal performance comparisons with data for a rectangular channel without fins showed that the presence of the diamond-shaped elements enhanced heat transfer by a factor of up to 4.4 for equal mass flow rate and by a factor of up to 1.65 for equal pumping power.