185975658 QUESTIONS1.The right surface of wall C is completely heat insulatedas shown in the figure. Inside wall C there is heat-2 °CTsgeneration. The outdoor temperature is -2 ° C and theh = 20 W/mkconvection heat transfer coefficient is h= 20 W/m*K. TheABheat conduction coefficients of walls A and B and C are25 cm50 cm25 cmkA – 25 W/mK, kR – 50 W/mK, kc – 75 W/mK.Last one digit ofyour studenta) Draw the temperature changing on the figure(W/m)b) For heat generation inside wall C, use the value in the table. Find the heat transfer rate number9 10to the external environment. A, B and C walls have a surface area of 5m2.110c) Find the maximum temperature since the temperature distribution equation for wall C is2 103 104:102given as T(x) =2kcE(L2 – x²) + T,455:1061057 108 109 106nsulation

The right surface of wall C is completely heat insulated as shown in the figure. Inside wall C there is heat generation. The outdoor temperature is -2 ° C and the convection heat transfer coefficient is h= 20 W/m*K. The heat conduction coefficients of walls A and B and C are kA - 25 W/mK, kn - 50 W/mK, kc - 75 W/mK.

The right surface of wall C is completely heat insulated as shown in the figure. Inside wall C there is heat generation. The outdoor temperature is -2 ° C and the convection heat transfer coefficient is h= 20 W/m*K. The heat conduction coefficients of walls A and B and C are kA - 25 W/mK, kn - 50 W/mK, kc - 75 W/mK.

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 2.46P: 2.46 The wall of a liquid-to-gas heat exchanger has a surface area on the liquid side of with a...

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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.
2.30 An electrical heater capable of generating 10,000 W is to be designed. The heating element is to be a stainless steel wire having an electrical resistivity of ohm-centimeter. The operating temperature of the stainless steel is to be no more than 1260°C. The heat transfer coefficient at the outer surface is expected to be no less than in a medium whose maximum temperature is 93°C. A transformer capable of delivering current at 9 and 12 V is available. Determine a suitable size for the wire, the current required, and discuss what effect a reduction in the heat transfer coefficient would have. (Hint: Demonstrate first that the temperature drop between the center and the surface of the wire is independent of the wire diameter, and determine its value.)
2.2 A small dam, which is idealized by a large slab 1.2 m thick, is to be completely poured in a short Period of time. The hydration of the concrete results in the equivalent of a distributed source of constant strength of 100 W/m3. If both dam surfaces are at 16°C, determine the maximum temperature to which the concrete will be subjected, assuming steady-state conditions. The thermal conductivity of the wet concrete can be taken as 0.84 W/m K.
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.
1.37 Mild steel nails were driven through a solid wood wall consisting of two layers, each 2.5-cm thick, for reinforcement. If the total cross-sectional area of the nails is 0.5% of the wall area, determine the unit thermal conductance of the composite wall and the percent of the total heat flow that passes through the nails when the temperature difference across the wall is 25°C. Neglect contact resistance between the wood layers.
Estimate the rate of heat loss per unit length from a 5-cm ID, 6-cm OD steel pipe covered with high-temperature insulation having a thermal conductivity of 0.11 W/(m K) and a thickness of 1.2 cm. Steam flows in the pipe. It has a quality of 99% and is at 150C. The unit thermal resistance at the inner wall is 0.0026(m2K)/W the heat transfer coefficient at the outer surface is 17W/(m2K) and the ambient temperature is 16C.
A plane wall, 7.5 cm thick, generates heat internally at the rate of 105 W/m3. One side of the wall is insulated, and the other side is exposed to an environment at 90C. The convection heat transfer coefficient between the wall and the environment is 500 W/m2 K. If the thermal conductivity of the wall is 12 W/m K, calculate the maximum temperature in the wall.
Heat is transferred at a rate of 0.1 kW through glass wool insulation (density=100kg/m3) with a 5-cm thickness and 2-m2 area. If the hot surface is at 70C, determine the temperature of the cooler surface.
3.16 A large, 2.54-cm.-thick copper plate is placed between two air streams. The heat transfer coefficient on one side is and on the other side is . If the temperature of both streams is suddenly changed from 38°C to 93°C, determine how long it takes for the copper plate to reach a temperature of 82°C.
2.46 The wall of a liquid-to-gas heat exchanger has a surface area on the liquid side of with a heat transfer coefficient of . On the other side of the heat exchanger wall flows a gas, and the wall has 96 thin rectangular steel fins 0.5 cm thick and 1.25 cm high as shown in the accompanying sketch. The fins are 3 m long and the heat transfer coefficient on the gas side is . Assuming that the thermal resistance of the wall is negligible, determine the rate of heat transfer if the overall temperature difference is .
A bare fuel rod has a diameter of 0.373 in and length of 12 ft. The volumetric heat generation rate for this rod is q ′′′ = 10,000 kW/ft3 . The heat produced by the rod is removed by water used as the coolant, at 2250 psia and 575 F. Find the heat transfer coefficient between the bare fuel rod and the coolant. The fuel rod surface temperature is 675 F. [Ans.: h = 2651 Btu/h·ft2 ·F].
One side of a 1 cm thick stainless steel wall (k1=19 W/m⁰C is maintained at180⁰C and the other side is insulated with a layer of 4 cm fibre glass(k2=0.04W/m ⁰C). The outside of the fiberglass is maintained at 60⁰C and theheat transfer rate through the wall is 300 W. Determine the area of the wall