= Q1 [20 marks] We here compare the efficiency of an Otto engine with the efficiency of a dual-cycle engine. The two eng

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Q1 20 Marks We Here Compare The Efficiency Of An Otto Engine With The Efficiency Of A Dual Cycle Engine The Two Eng 1 (203.7 KiB) Viewed 45 times

= Q1 [20 marks] We here compare the efficiency of an Otto engine with the efficiency of a dual-cycle engine. The two engine cycles, in terms of PV diagrams, are given in the figure below. The Otto engine is characterized by the volume ratio r =V2/V2 =V,/V4. The dual cycle engine is characterized by a compression ratio r. =V2/V3 , an expansion ratio r. =V/V, and a pressure ratio a = = PA/Pz. The conditions in the Otto engine and in the dual-cycle engine (dce) are the same at Points 2 of the two cycles: P2,0110 = 330 K. You are asked to determine efficiencies based on air-standard cycles with air to be considered an ideal gas with heat capacity ratio y=1.4. The ideal gas constant is R=8.31 J/(mol.K). As indicated in the figure, the compressions and expansions can be considered isentropic. a. Determine the efficiency of the Otto engine if r=18. [3 marks] b. Determine the efficiency of the dual cycle engine if r. =18, r = 14, and a = 1.5. [17 marks] Pzace =1.0x10 Pa; T2,010 -T2, ace 5 isentropic expansion isentropic expansion isentropic compression isentropic compression V v Otto engine cycle dual cycle engine