Spherical Thermocouple - GATE ME '04
A spherical thermocouple junction of a diameter of 0.706 mm is to be used for the measurement of the temperature of a gas stream. The convective heat transfer coefficient on the bead surface is 400 W/m^2.K. Thermo-physical properties of thermocouple material are k=20 W/m.K, C=400 J/kg.K, and ρ=8500 kg/m^3. If the thermocouple initially at 30 C is placed in a hot stream of 300 C the time taken by the bead to reach 298 C, is ________
A. 2.35 s B. 4.9 s C. 14.7 s D. 29.4 s
Ans:
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