a) Explanation Show the Otto cycle, on P − v diagram as in Figure (1). For the given air-standard diesel cycle, let v i , T i , P i , v r i , h i , and u i be the specific volume at i t h state, temperature at i t h state, pressure at i t h state, relative specific volume at i t h state, enthalpy at i t h state, and internal energy at i t h state respectively. Write the relation between the specific volume, and relative specific volume for the isentropic compression process 1-2. v r 2 = v 2 v 1 v r 1 v r 2 = 1 r v r 1 (I) Write the expression of ideal gas equation for air at state 1 of the cycle. m = P 1 V 1 R T 1 (II) Here, mass of air is m , and the gas constant is R . Write the expression of heat input to the cycle ( q i n ) . Q i n = m ( u 3 − u 2 ) (III) Conclusion: Refer Table A-17, “Ideal gas properties of air”, obtain the properties of air at 310 K ( T 1 ) , which gives 221.25 kJ / kg for u 1 , and 572.3 for v r 1 . Substitute 10.5 for r and 572.3 for v r 1 in Equation (I). v r 2 = 1 10.5 ( 572.3 ) = 54.50 Refer Table A-17, “Ideal gas properties of air”, obtain the properties of air at 54 b) To determine The thermal efficiency of the Otto cycle using variable specific heats. c) To determine The number of revolutions per minute required for a net work output of 45 kW.

8th Edition

ISBN: 9781307434316

Author: CENGEL

Publisher: INTER MCG

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Question

Chapter 9.12, Problem 159RP

To determine

The amount of heat supplied per cylinder.

To determine

The thermal efficiency of the Otto cycle using variable specific heats.

To determine

The number of revolutions per minute required for a net work output of 45 kW.

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Chapter 9.12, Problem 157RP

Chapter 9.12, Problem 161RP

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Chapter 9 Solutions

THERMODYNAMICS(SI UNITS,INTL.ED)EBOOK>I

Ch. 9.12 - What are the air-standard assumptions?Ch. 9.12 - What is the difference between air-standard...Ch. 9.12 - How does the thermal efficiency of an ideal cycle,...Ch. 9.12 - What does the area enclosed by the cycle represent...Ch. 9.12 - Prob. 5P Ch. 9.12 - Prob. 6P Ch. 9.12 - Can the mean effective pressure of an automobile...Ch. 9.12 - Prob. 8P Ch. 9.12 - What is the difference between spark-ignition and...Ch. 9.12 - Prob. 10P

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