A cold-storage room is separated from the outside atmosphere by a flat wall of area

PHYSICS · Multi-part · CBSE · Physics · Thermal Properties of Matter · Thermal Properties of Matter

Problem

A cold-storage room is separated from the outside atmosphere by a flat wall of area 8 m28\,\text{m}^2. Starting from the interior side, the wall consists of a 5 cm5\,\text{cm} thick layer of polyurethane foam (k=0.03 W m−1 K−1k = 0.03\,\text{W m}^{-1}\,\text{K}^{-1}) firmly bonded to a 10 cm10\,\text{cm} thick brick layer (k=0.60 W m−1 K−1k = 0.60\,\text{W m}^{-1}\,\text{K}^{-1}). The room air is maintained at −5∘C-5^{\circ}\text{C} while the outside air is at 35∘C35^{\circ}\text{C}. Steady one-dimensional heat flow may be assumed. (i) Calculate the rate of heat flow through the composite wall. (ii) Determine the temperature at the interface between the foam and the brick.

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