A 15-cm-wide and 18-cm-high vertical hot surface in 25°C air is to be cooled by a heat sin...

A 15-cm-wide and 18-cm-high vertical hot surface in 25°C air is to be cooled by a heat sink with equally spaced fins of rectangular profile. The fins are 0.1 cm thick and 18 cm long in the vertical direction. Determine the optimum fin height and the rate of heat transfer by natural convection from the heat sink if the base temperature is 85°C. The criteria for optimum fin height H in the literature is given by Take the thermal conductivity of fin material to be 177 W/m∙ °C