ch03_eu

# ch03_eu - ENGLISH UNIT PROBLEMS SOLUTION MANUAL CHAPTER 3...

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ENGLISH UNIT PROBLEMS SOLUTION MANUAL CHAPTER 3

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Borgnakke and Sonntag CHAPTER 3 SUBSECTION PROB NO. Concept-Study Guide Problems 136-140 Phase diagrams 141-142 General Tables 143-158 Ideal Gas 159-166 Review Problems 167-169 Compressibility Factor 170-171 Equations of state 172-173
Borgnakke and Sonntag Concept Problems

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Borgnakke and Sonntag 3.136 E Cabbage needs to be cooked (boiled) at 250 F. What pressure should the pressure cooker be set for? Solution: If I need liquid water at 250 F I must have a pressure that is at least the saturation pressure for this temperature. Table F.7.1: 250 F P sat = 29.823 psia.
Borgnakke and Sonntag 3.137 E If I have 1 ft 3 of ammonia at 15 psia, 60 F how much mass is that? Ammonia Tables F.8: F.8.1 P sat = 107.64 psia at 60 F so superheated vapor. F.8.2 v = 21.5641 ft 3 /lbm under subheading 15 psia m = V v = 1 ft 3 21.5641 ft 3 /lbm = 0.0464 lbm

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Borgnakke and Sonntag 3.138 E For water at 1 atm with a quality of 10% find the volume fraction of vapor. This is a two-phase state at a given pressure: Table F.7.2: v f = 0.01 672 ft 3 /lbm, v g = 26.8032 ft 3 /lbm From the definition of quality we get the masses from total mass, m, as m f = (1 – x) m, m g = x m The volumes are V f = m f v f = (1 – x) m v f , V g = m g v g = x m v g So the volume fraction of vapor is Fraction = V g V = V g V g + V f = x m v g x m v g + (1 – x)m v f = 0.1 × 26.8032 0.1 × 26.8032 + 0.9 × 0.016 72 = 2.68032 2.69537 = 0.9944 Notice that the liquid volume is only about 0.5% of the total. We could also have found the overall v = v f + xv fg and then V = m v.
Borgnakke and Sonntag 3.139 E Locate the state of R-134a at 30 psia, 20 F. Indicate in both the P-v and the T-v diagrams the location of the nearest states listed in the printed table F.10 From F.10: F.10.1 at 20 F P sat = 33.29 psi so we have superheated vapor. F.10.2 at 30 psi we find the state for 20F. T C.P. v 30 psia P C.P. v T 30 33.3 15.2 20 40 15.2 F 20 F 15 psia 33.3 psia

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Borgnakke and Sonntag 3.140 E Calculate the ideal gas constant for argon and hydrogen based on Table F.1 and verify the value with Table F.4 The gas constant for a substance can be found from the universal gas constant from table A.1 and the molecular weight from Table F.1 Argon: R = R _ M = 1.98589 39.948 = 0.04971 Btu lbm R = 38.683 lbf-ft lbm R Hydrogen: R = R _ M = 1.98589 2.016 = 0.98506 Btu lbm R = 766.5 lbf-ft lbm R Recall from Table A.1: 1 Btu = 778.1693 lbf-ft
Borgnakke and Sonntag Phase Diagrams

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Borgnakke and Sonntag 3.141 E Water at 80 F can exist in different phases dependent on the pressure. Give the approximate pressure range in lbf/in 2 for water being in each one of the three phases, vapor, liquid or solid. Solution:
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ch03_eu - ENGLISH UNIT PROBLEMS SOLUTION MANUAL CHAPTER 3...

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