Question

Questions 6-9 The walls of a refrigerator are typically constructed by sandwiching a layer of insulation between sheet metal panels. Consider a wall made from fiberglass insulation of thermal conductivity ki = 0.046 W/mK and thickness Li 50 mm and steel panels, each of thermal conductivity kp = 60 W/m. K and thickness Lp = 3 mm. If the wall separates refrigerated air at Too,i = 4°C from ambient air at T0o,0 = 25°C, what is the heat gain per unit surface area? Coefficients associated with natural convection at the inner and outer surfaces may be approximated as hi = ho = 5 W/m2K 4 = 0.050 m Refrigerated Too.j = 4°C h = 5 W/m2K Insulation ki = 0.046 W/m-K thit hp = 0,003 m Amblent air T.0,0 = 25°C IT ho = 5 W/m2K Panel (2) kg = 60 W/m-K Question 6 (1 point) The total thermal resistance R"tot (mºK/W) is 1.287 1.487 00.4 1.087 Question 7 (1 point) If the total thermal resistance R"tot is 1.0 m K/W, then what is the heat flux through the refrigerator wall, q" in W/m2 15 OOC 294

Answer 1

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