Evaluating ExergyA concrete slab measuring 0.3 m × 4 m × 6

Chapter 7, Problem 21P

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A concrete slab measuring \(0.3 \mathrm{~m} \times 4 \mathrm{~m} \times 6 \mathrm{~m}\), initially at 298 K, is exposed to the sun for several hours, after which its temperature is 301 K. The density of the concrete is 2300 \(\mathrm{~kg} / \mathrm{m}^3\) and its specific heat is c = \(0.88 \mathrm{~kJ} / \mathrm{kg} \cdot \mathrm{K}\). (a) Determine the increase in exergy of the slab, in kJ. (b) To what elevation, in m, would a 1000-kg mass have to be raised from zero elevation relative to the reference environment for its exergy to equal the exergy increase of the slab? Let \(T_0\) = 298 K, \(p_0\) = 1 atm, g = 9.81 \(\mathrm{~m} / \mathrm{s}^2\).