Chapter 15 Steady Heat Conduction3-56E A wall is to be constructed using solid bricks or identical size bricks with 9 square air holes. There is a 0.5 in thick sheetrock layer between two adjacent bricks on all four sides, and on both sides of the wall. The rates of heat transfer through the wall constructed of solid bricks and of bricks with air holes are to be determined. Assumptions1Heat transfer is steady since there is no indication of change with time. 2 Heat transfer through the wall is one-dimensional.3 Thermal conductivities are constant.4 Heat transfer coefficients account for the radiation heat transfer. PropertiesThe thermal conductivities are given to be k= 0.40 Btu/h⋅ft⋅°F for bricks, k= 0.015 Btu/h⋅ft⋅°F for air, and k= 0.10 Btu/h⋅ft⋅°F for sheetrock. Analysis (a) The representative surface area is . The thermal resistance network and the individual thermal resistances if the wall is constructed of solid bricks are A==(./ ).7 5 12 7 5 120 3906 ft2F/Btuh57.308ft)]12/5.0()12/7(F)[Btu/h.ft.10.0(ft12/9F/Btuh288ft)]12/5.0()12/5.7(F)[
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