p1.2-19 - a.) You want to design the heater so that it...

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1.2-19 Figure P1.2-19 illustrates a cross-section of a thermal protection suit that is being designed for an astronaut. 37 C b T = ° tissue th ins =4cm th ext =1mm th liner =1cm k liner =0.06W/m-K heater k ins =0.06W/m-K k ext =14.5W/m-K T space =4K ε =0.25 Figure P1.2-19: Cross-section of thermal protection suit. The suit consists of a liner that is immediately adjacent to the skin. The skin temperature is maintained at T b = 37ºC by the flow of blood in the tissue. The liner is th liner = 1 cm thick and has conductivity k liner = 0.06 W/m-K. A thin heater is installed at the outer surface of the liner. Outside of the heater is a layer of insulation that is th ins = 4 cm with conductivity k ins = 0.06 W/m-K. Finally, the outer layer of the suit is th ext = 1 mm thick with conductivity k ext = 14.5 W/m-K. The outer surface of the external layer has emissivity = 0.25 and is exposed by radiation only to outer space at T space = 4 K.
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Unformatted text preview: a.) You want to design the heater so that it completely eliminates any heat loss from the skin. What is the heat transfer per unit area required? b.) In order, rate the importance of the following design parameters to your result from (a): k ins , k ext , and . c.) Plot the heat transfer per unit area required to eliminate heat loss as a function of the emissivity, . While the average emissivity of the suit's external surface is = 0.25, you have found that this value can change substantially based on how dirty or polished the suit is. You are worried about these local variations causing the astronaut discomfort due to local hot and cold spots. d.) Assume that the heater power is kept at the value calculated in (a). Plot the rate of heat transfer from the skin as a function of the fractional change in the emissivity of the suit surface....
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This note was uploaded on 08/11/2008 for the course ME 364 taught by Professor Rothamer during the Summer '08 term at Wisconsin.

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