Q2/ A plane wall (K =17 W/m.°C ) with (60 mm) thick. Both sides of the wall are insulated with ( 2 cm) layer of insulating material having (K=0.22 W/m.C) . The heat transfer coefficient, considering convection on both sides of wall are ( 120 and 10 W/m².°C ) respectively. Calculate the heat transfer per unit area if the temperature difference across the wall is (90 °C).

Q2/ A plane wall (K =17 W/m.°C ) with (60 mm) thick. Both sides of the wall are insulated with ( 2 cm) layer of insulating material having (K=0.22 W/m.C) . The heat transfer coefficient, considering convection on both sides of wall are ( 120 and 10 W/m².°C ) respectively. Calculate the heat transfer per unit area if the temperature difference across the wall is (90 °C).

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter2: Steady Heat Conduction

Section: Chapter Questions

Problem 2.49P

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2.38 The addition of aluminum fins has been suggested to increase the rate of heat dissipation from one side of an electronic device 1 m wide and 1 m tall. The fins are to be rectangular in cross section, 2.5 cm long and 0.25 cm thick, as shown in the figure. There are to be 100 fins per meter. The convection heat transfer coefficient, both for the wall and the fins, is estimated to be K. With this information determine the percent increase in the rate of heat transfer of the finned wall compared to the bare wall.
1.10 A heat flux meter at the outer (cold) wall of a concrete building indicates that the heat loss through a wall of 10-cm thickness is . If a thermocouple at the inner surface of the wall indicates a temperature of 22°C while another at the outer surface shows 6°C, calculate the thermal conductivity of the concrete and compare your result with the value in Appendix 2, Table 11.
3.17 A 1.4-kg aluminum household iron has a 500-W heating element. The surface area is . The ambient temperature is 21°C, and the surface heat transfer coefficient is . How long after the iron is plugged in does its temperature reach 104°C?
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