2. A composite wall is made of 2 layers of different materials, A & B. the external surface of layer A is maintained at a constant temperature of 60°C, while the external surface of layer B is in contact with ambient air. The convective heat transfer coefficient for slab B is 8 W/m²K. Determine the temperatures T2 and T3. Assume the radiation emissivity of the external surface of layer B is equal to zero. Calculate the total heat transfer rate through the composite wall. External surface temperature of layer A T₁= 60°C Thermal conductivities: Layer A: 0.5 W/mK Layer B: 0.6 W/mK 3.5 m 5 cm 6 m pop T2 - Temperature between layers A & B 12 cm T3 - External surface temperature of layer B Ambient Air Convective air flow over layer B surface Free stream temperature Too = 28°C Convective heat transfer coefficient h = 8 W/m²K (Ans: T2= 52.5°C, T3= 37.4°C, Q=1581W)

2. A composite wall is made of 2 layers of different materials, A & B. the external surface of layer A is maintained at a constant temperature of 60°C, while the external surface of layer B is in contact with ambient air. The convective heat transfer coefficient for slab B is 8 W/m²K. Determine the temperatures T2 and T3. Assume the radiation emissivity of the external surface of layer B is equal to zero. Calculate the total heat transfer rate through the composite wall. External surface temperature of layer A T₁= 60°C Thermal conductivities: Layer A: 0.5 W/mK Layer B: 0.6 W/mK 3.5 m 5 cm 6 m pop T2 - Temperature between layers A & B 12 cm T3 - External surface temperature of layer B Ambient Air Convective air flow over layer B surface Free stream temperature Too = 28°C Convective heat transfer coefficient h = 8 W/m²K (Ans: T2= 52.5°C, T3= 37.4°C, Q=1581W)

College Physics

11th Edition

ISBN:9781305952300

Author:Raymond A. Serway, Chris Vuille

Publisher:Raymond A. Serway, Chris Vuille

Chapter1: Units, Trigonometry. And Vectors

Section: Chapter Questions

Problem 1CQ: Estimate the order of magnitude of the length, in meters, of each of the following; (a) a mouse, (b)...

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Concept explainers

Energy transfer

The flow of energy from one region to another region is referred to as energy transfer. Since energy is quantitative; it must be transferred to a body or a material to work or to heat the system.

Molar Specific Heat

Heat capacity is the amount of heat energy absorbed or released by a chemical substance per the change in temperature of that substance. The change in heat is also called enthalpy. The SI unit of heat capacity is Joules per Kelvin, which is (J K-1)

Thermal Properties of Matter

Thermal energy is described as one of the form of heat energy which flows from one body of higher temperature to the other with the lower temperature when these two bodies are placed in contact to each other. Heat is described as the form of energy which is transferred between the two systems or in between the systems and their surrounding by the virtue of difference in temperature. Calorimetry is that branch of science which helps in measuring the changes which are taking place in the heat energy of a given body.

Question

12.
A composite wall is made of 2 layers of different materials, A & B. the external
surface of layer A is maintained at a constant temperature of 60°C, while the
external surface of layer B is in contact with ambient air. The convective heat
transfer coefficient for slab B is 8 W/m²K. Determine the temperatures T2 and T3.
Assume the radiation emissivity of the external surface of layer B is equal to zero.
Calculate the total heat transfer rate through the composite wall.
External surface
temperature of layer A
T₁= 60°C
Thermal conductivities:
Layer A: 0.5 W/mK
Layer B: 0.6 W/mK
3.5 m
5 cm
6 m
Layer A
*
T2 - Temperature between layers A & B
12 cm
T3 - External surface temperature of layer B
Ambient Air
Convective air flow over
layer B surface
Free stream temperature
Too = 28°C
Convective heat transfer coefficient
h = 8 W/m²K
(Ans: T2= 52.5°C, T3= 37.4°C, Q=1581W)

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