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  3. 1 thermocouple a thermocouple is epoxied onto a high conductivity...

Question: 1 thermocouple a thermocouple is epoxied onto a high conductivity...

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1. Thermocouple. A thermocouple is epoxied onto a high conductivity surface in order to measure the temperature of the surface. The thermocouple consists of two wires, each bare and each having a diameter of Dw-0.51 mm. One wire is made ofchromel (Ni-10% Cr with k-17 W/m-K) and the other of constantan (Ni-45% Cu with k-23 W/m-K). The ends of the wires are welded together to create a measuring junction. The junction has dimensions of Dw by 2Dw. A layer of epoxy separates the thermocouple junction from the surface by 0.2 mm. The epoxy has a thermal conductivity of 0.5 W/m-K. The air surrounding the wires has a temperature of Too-20°C, The heat 。 transfer coefficient between each wire and the air ischrl h 25 W/m-K. The emissivity of each wire is 0.5. If the thermocouple reads a temperature of Ttc -40 °C, estimate the actual temperature Ts of the surface. tr

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