p3.1-7 - h = 30 W/m 2-K to h = 300 W/m 2-K a Can the sensor...

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3.1-7 You are building an instrument for measuring the heat transfer coefficient ( h ) between a sphere and a flowing fluid. The instrument is a spherical temperature sensor with diameter D = 3 mm that is initially in equilibrium with the fluid at T . The sensor has density ρ = 7500 kg/m 3 , specific heat capacity c = 820 J/kg-K, and conductivity k = 75 W/m-K. The sensor is heated with a constant rate of thermal energy generation of g ± = 0.1 W and the time required for the sensor temperature to increase by Δ T = 10 K is recorded. The range of the instrument is expected to be from
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Unformatted text preview: h = 30 W/m 2-K to h = 300 W/m 2-K. a.) Can the sensor be treated as a lumped capacitance? Justify your answer. b.) Assume that your answer from (a) is yes. Develop an equation that relates the measured time to the heat transfer coefficient. c.) Plot the heat transfer coefficient as a function of measured time. d.) Assume that you can measure time with an uncertainty of δ t meas = 0.1 s. Use your plot from (c) to estimate the uncertainty of your measurement of the heat transfer coefficient over the range of the sensor....
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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 University of Wisconsin.

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