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Unformatted text preview: T c 408.1 K = Z c 0.282 = C P 2.78 J gm K = P 1 4000 kPa = P 2 2000 kPa = molwt 58.123 gm mol = V c 262.7 cm 3 mol = Eq. (3.63) for volume of a saturated liquid may be used for the volume of a compressed liquid if the effect of pressure on liquid volume is neglected. T 359 360 361 K = T r T T c = T r 0.88 0.882 0.885 = (The elements are denoted by subscripts 1, 2, & 3 V V c Z c 1 T r ( 29 0.2857 = V 131.601 132.135 132.68 cm 3 mol = Assume that changes in T and V are negligible during throtling. Then Eq. (6.8) is integrated to yield: Chapter 6  Section A  Mathcad Solutions 6.7 At constant temperature Eqs. (6.25) and (6.26) can be written: dS  V dP = and dH 1 T  ( 29 V dP = For an estimate, assume properties independent of pressure. T 270 K = P 1 381 kPa = P 2 1200 kPa = V 1.551 10 3 m 3 kg = 2.095 10 3 K 1 = S  V P 2 P 1 ( 29 = H 1 T  ( 29 V P 2 P 1 ( 29 = S 2.661 J kg K = Ans. H 551.7 J kg = Ans. 6.8 Isobutane: 111 P 2 1500 bar = 250 10 6 K 1 = 45 10 6 bar 1 = V 1 1003 cm 3 kg = By Eq. (3.5), V 2 V 1 exp  P 2 P 1 ( 29 = V 2 937.574 cm 3 kg = V ave V 1 V 2 + 2 = V ave 970.287 cm 3 kg = By Eqs. (6.28) & (6.29), H V ave 1 T  ( 29 P 2 P 1 ( 29 = U H P 2 V 2 P 1 V 1  ( 29 = H 134.6 kJ kg = Ans. U 5.93 kJ kg = Ans. S  V ave P 2 P 1 ( 29 = Q T S = Work U Q = S 0.03636 kJ kg K = Ans. Q 10.84 kJ kg = Ans. Work 4.91 kJ kg = Ans. H T S V P + = but H = Then at 360 K, S V 1 P 2 P 1 ( 29 T 1 = S 0.733 J mol K = Ans. We use the additional values of T and V to estimate the volume expansivity: V V 3 V 1 = V 1.079 cm 3 mol = T T 3 T 1 = T 2K = 1 V 1 V T = 4.098755 10 3 K 1 = Assuming properties independent of pressure, Eq. (6.29) may be integrated to give S C P T T V P  = P P 2 P 1 = P 2 10 3 kPa = Whence T T 1 C P S V 1 P + ( 29 molwt = T 0.768 K = Ans. 6.9 T 298.15 K = P 1 1 bar = 112 Pr P Pc = Tr T Tc = .187 .000 .210 .200 .224 .048 .193 .210 .087 .094 .038 .400 .152 .140 = Pc 61.39 48.98 48.98 37.96 73.83 34.99 45.60 40.73 50.40 89.63 34.00 24.90 42.48 46.65 bar = Tc 308.3 150.9 562.2 425.1 304.2 132.9 556.4 553.6 282.3 373.5 126.2 568.7 369.8369....
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