Question

The outer surface of an engine is situated in a place where oil leakage can occur. When leaked oil comes in contact with a hot surface that has a temperature above its autoignition temperature, the oil can ignite spontaneously. Consider an engine cover that is made of a stainless steel plate with a thickness of 1 cm and a thermal conductivity of 14 W/m·K. The inner surface of the engine cover is exposed to hot air with a convection heat transfer coefficient of 7 W/m2·K at 333°C. The outer surface is exposed to an environment where the ambient air is 69°C with a convection heat transfer coefficient of 7 W/m2·K. To prevent fire hazard in the event of oil leak on the engine cover, a layer of thermal barrier coating (TBC) with a thermal conductivity of 1.1 W/m·K is applied on the engine cover outer surface. Calculate the cover surface temperature for the TBC layer of 0.028 m thickness.

Answer 1

Answer:

Outer Surface Temperature = 138.53°C

Explanation

Calculating inner convection resistance, Ri

Ri = 1/hi

Ri = 1/7

Ri = 0.1423

Then we calculate the engine cover resistance

R1 = L1/k1

R1 = 0.01/14

R1 = 0.000714

See attachment

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Answer 2

Answer:

The outer surface temperature is 196.2 C which is lower than 200 C  thus TBC layer of  0.028 m thickness  will be sufficient to prevent fire hazard.