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Be neat, write out equations before inserting numbers, and circle your answers. If you cannot ﬁgure out one part, assume an answer and carry iétthrﬁmgh the other parts.
f5 6/ a ” : l. 534%) A sealed cylinder contains 1.5 kg of R1 345111321 volumeiof 0.02 m3 on one
side of a frictionless piston and 0.3 kg oxygen (02) on the other side of the piston.
Initially both ﬂuids are at a temperature of 25°C. The R 134a then receives 1000
Id of heat from a reversible heat transfer reservoir at a temperature of 600°C after
which the volume of the 02 is 1/2 its initial volume, compressed in a reversible
process in which there is no heat transfer to/from the 02. Assume variable
speciﬁc heats for the 02. 21) Find the ﬁnal temperature of the oxygen (0C).
b) Find the ﬁnal pressure of the oxygen (kPa). ..‘. ..’..,1_.h,.!‘\ g; «u; u ‘ I ‘ l £7 0'2
' d) Fin the ﬁnal temperaturme C? 6) Find the entropy generation for this process Gel/K). Problem 1 continued jyle’JW‘of O J C) m (WM) ﬁﬁ’bx/ 0/
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32/344 z I) j: /r . J Kl V69 FA : 20.30 : im/gsJ ’  its. // 2. (31%) Steam enters a horizontal 6—inch diameter pipe as a saturated vapor at 20
psia with a velocity of 30 m/s and exits at a pressure of 14.7 psia and a quality of 95%.
There is heat transfer to the surroundings which a& at 80°F. Determine:
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a) The velocity at the exit of the pipe (ﬁ/s) b 5 Q
c. Jar)” The rate of entropy generation for the pipe and its surroundings. 20 ‘19 g 30"? (9
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3. (64%) Air at 100 kPa, 17°C is compressed to 400 kPa after which it is expanded
through a nozzle back to the atmosphere at 100 kPa. The compressor and the nozzle both
have efﬁciencies of 90% and the kinetic energy in/out of the compressor can be \ / 1"
neglected. Assume constant speciﬁc heat for the air. Find: C,» Lao: we. 7M5; Z a) The actual compressor work (kJ/kg). [L
b) The compressor exit temperature (0C). @l4
c) The actual nozzle exit velocity 4 0
d) Qualatatively sketch the process on a Ts diagram ‘ )Z 2' y
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 Fall '07
 Schmidt
 Thermodynamics, Entropy, Heat, Heat Transfer, entropy generation, Reversible heat transfer

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