Question

Analyze a Diesel cycle using a constant specific heat air standard model (cP = 1.004 kJ/kg-K, R = 0.287 kJ/kg-K) with the following properties: The temperature and pressure at the beginning of the compression stroke are 300 K and 100 kPa, the compression ratio is 22, and the specific heat addition is 800 kJ/kg. Find the thermal efficiency, cut off ratio, maximum temperature in the cycle, and maximum pressure in the cycle.

Answer 1

T= 300k , P = 100 kPa compression ratio (Y) = 22 Heat Addition = 800 ICT 14 I. (Vok cp-c = R a = 1.004 - 0.287 a = 0.717 K = 1.4 1.4-1 K = CP = 1.4 T2 = 300 (22) w T2 = 1032.976 OK Heat addition - 6 • - Heat addition = G [Ts - Tz ? 800 = 1.004 [T3 - 1032. 976] Tg = 1829.789 OK Maximum Temperature = = 1829.789 K Pirk - Park >> P = Px 1.4 . f, *lo" 100x 22" - Maximum Pre suure = P2 = 7575.159 kPa cut off ratio (8)= 1829.789 1032.976 = 1.7714 T2

Ta = Tix 8X 1s = cut off ratio] 1.4 To = 300 x 1.7414't = 667.982 'n Heat Rejection = ax [Te-T,} = 0.714 [667.982-300) • = 261.26722 - Bad O addition - I rejection Qaddition = 800 - 261.26 722 th = 0.67 34 ~ 67.34 / 800