The wind chill, which is experienced on a cold, windy day, is related to increased heat transfer from exposed human skin to the surrounding atmosphere. Consider a layer of fatty tissue that is 3 mm thick and whose interior surface is maintained at a temperature of 36 C. On a calm day the convection heat transfer coefficient at the outer surface is 25 W/m2.K, but with 30 km/h winds it reaches 65 W/m2.K. In both cases the ambient air temperature is 15 C. A) What is the ratio of the heat loss perunit area from the skin for the calm day to that for the windyday?
B) What will be the skin outer surfacetemperature for the calm day? For the windy day?
C) What temperature would the air have toassume on the calm day to produce the same heat loss occurring withthe air temperature at -15ºC on the windy day?