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/m^2 * K, but with 30 km/h winds it reaches 65 W/m^2 * K. In both cases the ambient air temperature is −15°C. k value for fatty tissue is 0.2W/mK.(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?

answer:

a

explanation:

answer:

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answer:

not sure

explanation:

A Carnot heat engine receives heat from a reservoir at 900$^\circ{}$C at a rate of 800 kJ/min and rejects the waste heat to the ambient air at 27$^\circ{}$C. The entire work output of the heat engine is used to drive a refrigerator that removes heat from the refrigerated space at -5$^\circ{}$C and transfers it to the same ambient air at 27$^\circ{}$C. Determine (a) the maximum rate of heat removal from the refrigerated space and (b) the total rate of heat rejection to the ambient air. Answers: (a) 4982 kJ/min, (b) 5782 kJ/min