During transportation and storage of food, unexpected and undesired variations in the surrounding temperature can pose health hazards if the temperature rises or lowers to the range for optimum...

During transportation and storage of food, unexpected and undesired variations in the surrounding temperature can pose health hazards if the temperature rises or lowers to the range for optimum bacterial growth. Consider one of the frozen hamburger patties from Problem 7.7, left on the countertop by mistake. Assume that it is initially frozen, with a uniform temperature of -5°C, and that there is no heat transfer from the bottom of the patty. The room air temperature is at 30°C and the heat transfer coefficient at the top of the patty from natural convection is 10 W / m2 k. The unfrozen patty has 75% water and a thermal conductivity of 0.4 W / m k, a density of 1040 kg/ m3, and a freezing temperature of -5°C. The latent heat of fusion of pure water is 335 kJ/kg. The dimensions of the patty are given by a thickness of 2 cm and a diameter of 8 cm. Neglecting the sensible heat change, how long would it take for the hamburger to completely thaw from its initial frozen state?