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GATE ME 2022: Heat Tranfer
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Question 1
A long cylindrical pipe is wrapped with an insulating material. Up to the critical radius of insulation ________.
Question 2
The copper fins having square cross sectional area (1mm x 1mm) of 15mm length are provided on a motor to carry 1.5 w of energy generated by this motor The temperature of the surface of casing of motor should not exceeds 1000c when surrounding temperature is 300c. Assume k(copper)=200w/m0c, h=15w/m2 0c and neglect heat loss from the tip of fin. Find the number of fins required
Question 3
A square plate of 1000 Watt electric heater 15 cm × 15 cm is inserted between two slabs. Slab A is 2 cm thick (k = 50 W/m-K) and slab B is 1 cm thick (k = 0.2 W/m-K). The outside heat transfer coefficients on side A and side B are 200 W/m2-K and 50 W/m2-K respectively. The temperature of surrounding air is 30 °C. The maximum temperature in the system is ___________ °C.
Question 4
Lubricating oil (ρ = 865 kg/m3, k = 0.14 W/m-K, cp = 1.78 kJ/kg-K and ν = 9 × 10-6 m2/s) at 60 °C enters a 1 cm diameter tube with a velocity of 3.5 m/s. The Prandtl number will be _____.
Question 5
A counter flow double pipe heat exchanger using superheated steam is used to heat water at the rate of 10500 kg/h. The steam enters the heat exchanger at 180 °C and leaves at 130 °C. The inlet and exit temperatures of water are 30 °C and 80 °C respectively. If overall heat transfer coefficient from steam to water is 814 W/m2 °C. The heat transfer area is
Question 6
Find the radiation heat exchange between two large parallel steel plates of emissivities 0.7 and 0.5 held at temperatures of 1000 K and 500 K respectively, if a thin copper plate of emissivity 0.1 is introduced as a radiation shield between the two plates is?
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May 17ESE & GATE ME
