Reference no: EM13978269
You are trying to improve an engine that you are working on in your hobby shop. Currently, your engine is based upon the Stirling cycle shown in the figure on the left. You decide to modify the Stirling cycle in the following two ways:
1) The isothermal compression continues past volume Va until the pressure reaches pb.
2) The gas is then held at pressure pb while it expands from Ve to Va.
This gives you the "modified Stirling cycle", shown in the figure on the right.
The working gas in this engine is 1.00 mole of methane (CH4), a polyatomic gas that translates and rotates but does not oscillate. The low temperature reservoir is at TL = 300 K, and the high temperature reservoir is at TH = 450 K. At point a, the methane has volume Va = 2.5 x 10-4 m3 (or one quarter of a liter) and is at pressure pa = 9.98 x 106 Pa. The volume of the methane at point d is Vd = 4Va.
Answer the questions below. Report all of your answers to four significant figures.
(a) What are the pressure pb and the volume Ve?
(b) If the methane does WOS = 1.73 kJ of work during the original Stirling cycle, how much work WMS does the methane do during one cycle of the modified Stirling cycle?
(c) If Qabc = 8.93 kJ of heat is added to the methane during process abc of the original Stirling cycle, how much heat Qaeb is added during process aeb of the modified Stirling cycle?
(d) Compare the efficiency E(epsilon)MS of the modified cycle to the efficiency E(epsilon)OS of the original cycle. Does this modification of the Sterling cycle make financial sense in terms of energy costs? (For example, if EMS > EOS, is it appreciably larger?)
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: What are the pressure pb and the volume Ve? If the methane does WOS = 1.73 kJ of work during the original Stirling cycle, how much work WMS does the methane do during one cycle of the modified Stirling cycle?
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