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Question: me 302engineering heat transfer steps for solving heat transfer problems...

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ME 302-ENGINEERING HEAT TRANSFER Steps for Solving Heat Transfer Problems I. Problem Statement/Solution: Briefly state what is known about the problem in your own words, give the key information and state what is required to be determined. This ensures that you understand the problem and what is to be solved 2. Diagram: Sketch the physical system and identify relevant heat transfer processes and mass transfer interactions. Also list the relevant given information. Look for possible properties, which remain constant during a process and identify them on the sketch. 3. List the assumptions and any approximations made to make it possible for the problem to be solved. Note that some of the assumptions may be given in the problem Properties: The properties necessary for the solution of the problem should be determined. Most of the unknown properties can be obtained from tables and charts in the Appendix at the back of the textbook. Analysis or Calculations: Begin to solve the problem by applying the relevant energy conservation, conduction, convection and radiation equations. By using the assumptions made, these equations can be reduced to simpler equations. Solve as far as possible before substituting numerical values. Retain the digits in the given data during the calculations and round up the results or answer to appropriate number of significant digits. 5. If required or necessary,discuss your results to include key reasoning. conclusions and scope or effects of your assumptions.

2-42 Consider the East wall of a house that has a thickness of L. The outer surface of the wall exchanges heat by both convection and radiation. The interior of the house is main- tained at Tat, while the ambient air temperature outside remains at T2. The sky, the ground, and the surfaces of the surrounding structures at this location can be modeled as a sur- face at an effective temperature of Tky for radiation exchange on the outer surface. The radiation exchange between the inner surface of the wall and the surfaces of the walls, floor, and ceil- ing it faces is negligible. The convection heat tra cients on the inner and outer surfaces of the wall are h and h, nsfer coeffi- - respectively. The thermal conductivity of the wall material is k and the emissivity of the outer surface is ε. Assuming the heat

transfer through the wall to be steady and one-dimensional, express the mathematical formulation (the differential equa- tion and the boundary and initial conditions) of this heat con- duction problem. Do not solve. sky Wall di ter wa tra 0 FIGURE P2-42
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