Air is cooled from 1100 R to 500 R. Considering the variability of the specific heats, determine the change in specific internal energy and the change in specific enthalpy for the process.
Given: T1 = 1100 R; T2 = 500 R
What will be an ideal response?
From the air tables or on-line air properties: h1 = 266.0 Btu/lbm; u1 = 190.6 Btu/lbm
h2 = 119.5 Btu/lbm; u2 = 85.20 Btu/lbm
So,?h = h2 – h1 = -146.5 Btu/lbm
?u = u2 – u1 = -105.4 Btu/lbm
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