- Heat Transfer - Section 1
- Heat Transfer - Section 2
- Heat Transfer - Section 3
- Heat Transfer - Section 4
- Heat Transfer - Section 5
- Heat Transfer - Section 6
- Heat Transfer - Section 7
- Heat Transfer - Section 8
- Heat Transfer - Section 9
- Heat Transfer - Section 10
- Heat Transfer - Section 11


Heat Transfer - Engineering
Q1: The inner wall of a furnace is at a temperature of 700°C. The composite wall is made of two substances, 10 and 20 cm thick with thermal conductivities of 0.05 and 0.1 W.m-1.°C-1 respectively. The ambient air is at 30°C and the heat transfer co-efficient between the outer surface of wall and air is 20 W.m-2.°C-1. The rate of heat loss from the outer surface in W.m-2isA 165.4
B 167.5
C 172.5
D 175
ANS:A - 165.4 To find the rate of heat loss from the outer surface of the wall, we can use the concept of thermal resistance and Fourier's law of heat conduction. The total thermal resistance (𝑅𝑡𝑜𝑡𝑎𝑙Rtotal) of the composite wall is the sum of the thermal resistances of its individual layers. The thermal resistance (𝑅R) of a layer is given by: 𝑅=𝐿𝑘×𝐴R=k×AL Where:
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