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# exam1_key - Printed Name Problem 1 2 3 4 Total Score ChE...

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Printed Name: Problem Score 1 2 3 4 Total ChE 330 Exam 1: Winter 2002 Open Book Your Course Notes, Course Handouts, and Text Only! There are 9 pages including the cover for this exam Write and Sign the Honor Code Signature: 1

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Initials: 2 1. (25 pts) Short Answers a) (5 pts) In the energy balance on a pump is W positive or negative? A pump requires energy so W is positive. b) b) (5 pts) At the same T and P , which has the higher entropy ice, liquid water, or steam? Explain. Steam, entropy is measure of disorder, gases are more random than liquids or solids c) (5 pts) Estimate the maximum possible thermal efficiency of an automobile engine. η = 1 - T c T h T c = 300 and T h = 600 any reasonable T h is OK Maximum is 0 . 5
Initials: 3 d) (5 pts) On this T - S chart sketch the lines of constant pressure. T S e) (5 pts) At constant volume the pressure on a container of an ideal gas is in- creased to a factor of 3 times its original value. Is the final temperature: Higher. Lower. It depends on whether Q is positive, negative, or zero. Explain your answer. PV = RT for an ideal gas at constant V increase P must increase T .

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Initials: 4 2. (35 pts) A compressor takes in steam at P = 0 . 1MPa and and T = 150C and compresses it to a final pressure of P = 1 . 2MPa. a) (10 pts) What are the energy and entropy balances for this process? Δ H = W Δ S = S gen b) (15 pts) If the compressor is reversible what is the final temperature and work required? Solve using steam tables Δ S = 0 Read from table at P = 0 . 1MPa and and T = 150C S in = S out = 7 . 6148kj / kg / K H in = 2776 . 6kj / kg Find in table at P = 1 . 2MPa at T = 450 S = 7 . 5332 at T = 500 S = 7 . 6779 the fraction is 7 . 6148 - 7 . 5332 7 .
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exam1_key - Printed Name Problem 1 2 3 4 Total Score ChE...

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