Question

An air standard Otto cycle at the initial condition of P,=1 bar, T,=290 °K, V = 400 cm². The maximum temperature of the engine is 2200°K and compression ratio is 8. The mass of air is assumed to be 4.8x104kg. Assume isentropic process exits in both compression and expansion strokes. (a) Sketch the P-V and T-S diagram of the cycle (5%), (b) determine the total heat addition to the gas in kj (20%). (c) Net cycle work output of the engine (5%) and (d) the thermal efficiency of the cycle (5%).

Answer 1

Solm for otto ayde. a P-V and T-S diagram Р 3 3 T 4 Sout 9. ► P S process 1 de 2- 3 Isentoopic compression Constant volume Heat addition Isentropic expansion Constant volume Heat rejection. 3-04 4-DL Criven Data ; 3 Pje Ibar ; T = 290 K ; vi= 400 cm3 400 x 100 m T3 = ૨૨eo K Compression ratio (a)= V V2 - V2 = 400x106 50X166 m3 8 mass of air cm): 4.88164 lieg B Heat addition of gas. = for Isentoopic Compression 7-1 Tz Pe P Z V₂ TI 1.4) .: Te - 290 (8) i Pa= 1 x 18014 Pe= 18.38 bar | Te = 666.24 K

for constant volume Heat addition, Pa Pa Athos i P3 18.38 x Blog 666.24 P₂ = 60.7 bar > Total Heat added at constant volume Sin = mwltz-T2 ) (4.8x164) (0.718) Ceroo - 666.24) KI Sim 2 0.5286 kJ Am

@ Thermal efficiency - Thermal efficieny of otto cycle given as 7=(- = [-] x 100 yy. 그 ;-) r 1 ) g 100

M = (1 - 0.4353 ) x 100 V. 12 $ 56.47 y Ame ③ Net coork output = Thermal What out efficiency on Sin .. 0,5647 Wirel 0,5286 2 Whet = 0.299 KI Are

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