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Unformatted text preview: 19.14 (a) Calculate the heat flux through a sheet of steel 10 mm (0.39 in.) thick if the temperatures at the two faces are 300 and 100°C (572 and 212°F); assume steady-state heat flow. (b) What is the heat loss per hour if the area of the sheet is 0.25 m 2 (2.7 ft 2 )? (c) What will be the heat loss per hour if soda–lime glass instead of steel is used? (d) Calculate the heat loss per hour if steel is used and the thickness is increased to 20 mm (0.79 in.). 19.15 (a) Would you expect Equation 19.7 to be valid for ceramic and polymeric materials? Why or why not? (b) Estimate the value for the Wiedemann– Franz constant L [in Ω-W/(K) 2 ] at room temperature (293 K) for the following nonmetals: silicon (intrinsic), glass-ceramic (Pyroceram), fused silica, polycarbonate, and polytetrafluoroethylene. Consult Tables B.7 and B.9 in Appendix B....
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This note was uploaded on 06/02/2011 for the course ECONMICS ECN204 taught by Professor Brenan during the Spring '08 term at Ryerson.
- Spring '08