Chapter 1 Basics of Heat TransferAssumptions 1Steady operating conditions exist since the temperature readings do not change with time. 2 Heat losses through the lateral surfaces of the apparatus are negligible since those surfaces are well-insulated, and thus the entire heat generated by the heater is conducted through the samples.3 The apparatus possesses thermal symmetry. AnalysisThe electrical power consumed by the heater and converted to heat is &()(.)WVIe===1100 666V AWQ 3 cm 3 cm The rate of heat flow through each sample is &&QWe=26633W2W Then the thermal conductivity of the sample becomes ADQkATLkQLAT=⎯→⎯==°=°ππ22400440 001257330 00125710(.).&&()()mm=W)(0.03 m)mC22ΔΔ78.8 W / m. C1-68 The thermal conductivity of a material is to be determined by ensuring one-dimensional heat conduction, and by measuring temperatures when steady operating conditions are reached.
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