Plank ’ s equation is being used to estimate the convective heat transfer coefficient in a food being frozen in an air-blast freezer. It took a product 20 min to freeze in the freezer. The product is in the shape of an infinite cylinder with a diameter of 2 cm. The properties of the product are as follows: Thermal conductivity of frozen material 5 1.8 W/(m 8 C) , density 5 890 kg/m 3 , and latent heat of fusion 5 260 kJ/kg , initial freezing point 5 2 1.9 8 C. The initial temperature of the product is 25 8 C and the air temperature is 2 35 8 C.