Answered: Temperature profile in a wall (t = 0.1…

Temperature profile in a wall (t = 0.1 m, k = 75 W/m/C) is given by T=-15x + 70. Determine heat flux across the wall and temperature at the edges of wall.

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 2.54P

See similar textbooks

Similar questions

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?
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.)
B: A composite wall is consist of two blocks A and B. Wall A (ka- 75 W/m. °C and thickness La) contains uniform heat generation q = 1.5×106 W/m³ and isolated from the left side. Wall B (kb 150 W/m. °C and thickness L) has no generation and exposed from the right side to moving water (To= 30 C and h=1000 W/m2). If the rate of heat flux transfer to water is 75000 W/m², and the temperature at the interface between block A and B is 115 C, determine: 1- The thickness of block A and B. 2- The inner and outer surface temperature of the composite.
Q1: Consider one-dimensional conduction in a plane composite wall (Im x Im) as shown in the figure below. The outer surfaces are exposed to a fluid at 25°C and a convection heat transfer coefficient of 1000 W/m K. The middle wall B experiences uniform heat generation dg, while there is no generation in walls A and C. The temperatures at the interfaces are T=261°C and T; -211°C. Assuming negligible contact resistance at the interfaces: A) Determine the outside surface temperature of walls A and C? B) Compute the value of dg? (20 M) A B. ーム k= 25 Wim-K A = 50 W/m-K L = 30 mm Le= 30 mm L = 20 mm %3D
Q1: Consider a large plane wall of thickness L = 0.4 m, thermal conductivity k=2.3 W/m °C, and surface area A= 20 m2. The left side of the wall at x= 0 is subjected of T1 = 80°C. while the right side losses heated by convection to the surrounding air at T-15 °C with a heat transfer coefficient of h=24 W/m2 C. Assuming constant thermal conductivity and no heat generation in the wall, (a) express the differential equation and the boundary conditions for steady one-dimensional heat conduction through the wall, (b) obtain a relation for the variation of temperature in the wall by solving the differential equation, and (c) evaluate the rate of heat transfer through the wall Ans : (c) 6030 W
Q₁: Consider a large plane wall of thickness L = 0.4 m, thermal conductivity k-2.3 W/m °C, and surface area A= 20 m². The left side of the wall at x= 0 is subjected of T1 = 80°C. while the right side losses heated by convection to the surrounding air at T-15 °C with a heat transfer coefficient of h=24 W/m² °C. Assuming constant thermal conductivity and no heat generation in the wall, (a) express the differential equation and the boundary conditions for steady one-dimensional heat conduction through the wall, (b) obtain a relation for the variation of temperature in the wall by solving the differential equation, and (c) evaluate the rate of heat transfer through the wall Ans: (c) 6030 W
a. The wall of a building has a surface area of 50 m2. The outside layer of the wall is 20 cm thick concrete with thermal conductivity kcon = .8 W/m-K. The inner layer is 10 cm thick balsa wood (kbalsa = .048 W/m-K) as an insulator. Outside temperatures of 47o C are expected, while an inside temperature of 21o C is maintained by the cooling system. Find the rate of heat transfer through the wall.
Q: A large plane wall of thickness (L= 0.3 m), thermal conductivity (k = 40 W/m-°C), and surface area 0.4 m2. The left side of the wall is maintained at a constant temperature of 70°C while the right side loses heat to the surrounding air with heat flux q' expressed by: 1200k q = k+20L A- Find a relation to determine the variation of temperature in the wall. B- Determine the rate of heat transfer through the wall. C- Determine the temperature at the right side of the wall. wall T1= 70 °C L= 0.3m
Q1: Consider one-dimensional conduction in a plane composite wall (1m x Im) as shown in the figure below. The outer surfaces are exposed to a fluid at 25°C and a convection heat transfer coefficient of 1000 W/m2.K. The middle wall B experiences uniform heat generation dB, while there is no generation in walls A and C. The temperatures at the interfaces are T1=261°C and T2=211°C. Assuming negligible contact resistance at the interfaces: A) Determine the outside surface temperature of walls A and C? B) Compute the value of q;? T2 T h 25 241 A B -2LB Lc .03 Ta kA = 25 W/m-K kc = 50 W/m-K LA = 30 mm Lg = 30 mm Lc = 20 mm %3D
Problems within the wall is T(x) = a(L- ) +b where a = 10°C/m2 and b 30°C, what is the thermal con- ductivity of the wall? What is the value of the convec- tion heat transfer coefficient, h? 2.11 Consider steady-state conditions for one-dimensional conduction in a plane wall having a thermal conductiv- ity k 50 W/m K and a thickness L = 0.25 m, with no internal heat generation. 2. T2 T1 L Determine the heat flux and the unknown quantity for each case and sketch the temperature distribution, indi- cating the direction of the heat flux. 2 Case TC) dTldx (K/m) T2(°C) 1 50 -20 2 -30 - 10 3 70 160 4 40 -80 5 30 200
A 1-D conduction in a plane composite wall. The outer surfaces are exposed to a fluid at 25 °C and a convection heat transfer coefficient of 1000 W/m²/K. The middle wall B experiences uniform heat generation qB, while there is no generation in walls A and C. The temperatures at the interfaces are T₁ = 261 °C and T₂ = 211 °C. Find ġ and thermal conductivity kg. T₁ T2 Too, h 111 A B ав -2LB KA = 25 W/m.K kc = 50 W/m.K Ick LA = 30 mm LB = 30 mm Lc = 20 mm Too, h