A small oven with a surface area of 0.28 m2 is located in a room in which the walls and the air are at a temperature of 27°C. The exterior surface of the oven is at 150°C and the net heat transfer by radiation between the oven’s surface and the surroundings is 586 W. If the average convective heat transfer coefficient between the oven and the surrounding air is 11 W/(m2 K), calculate: (a) the net heat transfer between the oven and the surroundings in W, (b) the thermal resistance at the surface for radiation and convection, respectively, in K/W, and (c) the combined heat transfer coefficient in W/(m2 K).

GIVEN



FIND



ASSUMPTIONS

- Steady state prevails

SKETCH


(a) The net heat transfer is the sum of the convective heat transfer, the net

radiative heat transfer



(b) The radiative resistance is



The convective resistance is



These two resistances are in parallel, therefore the total resistance is given by



(c) The combined heat transfer coefficient can be calculated from

Physics & Space Science

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