Sheet-2- steady state conduction
Q1/Find the heat transfer per unit area through the composite wall in Figure. Assume one dimensional heat flow?
Q2/A furnace wall is composed of three layers, 10 cm of firebrick (k=1.560 W/m. K), followed by 23 cm of kaolin insulating brick (k=0.073 W/m. K), and finally 5 cm of masonry brick (k=1.0 W/m.K).The temperature of the inner wall surface is 1370 K and the outer surface is at 360 K. What are the temperatures at the contacting surfaces?
Q3/A double-pane window consists of two 3-mm thick layers of glass separated by a 12-mm wide stagnant air space. For specified indoors and outdoors temperatures, determine the rate of heat loss through the window and the inner surface temperature of the window? K glass= 0.78 W/m?°C and K air= 0.026 W/m?°C.
Q4/ The interior of a refrigerator having inside dimensions of base area and 1m height, is to be maintained at 6°C. The walls of the refrigerator are constructed of two mild steel sheets 3mm thick (k = 46.5 W/m°C) with 50 mm of glass wool insulation (k = 0.046 W/m°C) between them. If the average heat transfer coefficients at the inner and outer surfaces are 11.6 W/m2°C and 14.5 W/m2°C respectively, calculate: (i) The rate at which heat must be removed from the interior to maintain the specified temperature in the kitchen at 25°C, and
(ii) The temperature on the outer surface of the metal sheet.
Q5/A mild steel tank of wall thickness 10mm contains water at 90C .Calculate the rate of heat loss per m2 of tank surface area when the atmospheric temperature 15 C. The thermal conductivity of mild steel is 50W/m.k, and the heat transfer coefficients for inside and outside the tank are 2800 and 11 W/m2.k respectively. Calculate also the temperature of the outside surface of the tank?
Q6/For the composite materials shown in the figure:-
1-Sketch the equivalent electrical circuit.
2-Determine the rate of heat transfer through the materials per unit depth.
3-Detrmine T1 and T2
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