# Problem 11-1 - Example 11-1 The compression ratio of a cold...

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Example 11-1 The compression ratio of a cold air-standard Otto cycle is 8. At the end of the expansion process, the pressure is 90 psia and the temperature is 900 R. The heat rejection from the cycle is 70 Btu per lbm of air. Assuming k = 1.4, find a) the net work, in Btu/lbm of air b) the thermal efficiency c) the maximum and minimum temperatures Solution: a) net in out WQ Q =− () 41 out Qm u u out v c T T Btu cv(air, 77) 0.171 lbm R v cT == = out v Q cT T m 14 out v Q TT mc

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1 Btu 70 lbm 900 R Btu 0.171 lbm R T =− 1 491 R T = 1 21 12 k TV ⎛⎞ = ⎜⎟ ⎝⎠ () ( ) 1 1.4 1 1 2 491 R 8 k V TT V == 2 1127 R T = 1 1 41 34 4 32 k k VV T ( ) 1.4 1 3 900 R
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## This homework help was uploaded on 04/07/2008 for the course MANE 4010 taught by Professor Kaminski during the Spring '08 term at Rensselaer Polytechnic Institute.

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Problem 11-1 - Example 11-1 The compression ratio of a cold...

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