Heat is convected away from an object at the rate given by the following formula

Question

Heat is convected away from an object at the rate given by the following formula: (deltaQ/deltaT) = hA(deltaT).

h: coefficient that depends on the shape and the orientation of the object.

A: area

deltaT: temperature difference.

Calculate the rate of convective heat loss in Watts for an unclothed person standing in air at 23 degrees Celsius. Assume that the skin temperature is 34 degrees Celsuis and that the body surface area is 1.5m^2. Calculate for ALL OF THE GIVEN air speeds below:

h= 6 W/m^2C                 air speed = still

h= 12 W/m^2C               air speed = 1 m/sec

Explanation / Answer

1) (deltaQ/deltaT) still air = 6*1.5*11=99 W

2)(deltaQ/deltaT) for air=1m/s = 12*1.5*11=198W

3)(deltaQ/deltaT) for air = 5 m/s = 28*1.5*11=462 W

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