Question

A Diesel engine is approximated by a pressure limited (dual) cycle. The data is as follows: Inlet temperature and pressure: P1 = 100 kPa, T = 298 K Compression ratio = 16:1 Heat added during combustion = 44000 kJ/kgfuel (please note that this value is per kg fuel) A/F = 23 kg/kgf 40% of the heat is added in the constant volume combustion part. k=1.3, CH = 0.81 kJ/kg.K, isentropic expansion and compression Find the values of pressure rise parameter and cut-off ratio.

Answer 1

Quyi, Griveni - Dual Cycle T=298K , P = 100 kPa r = 16:1 o added = 44,000 kJ/kg fuel P/f = 23 kg ain/kg fuel K=1.3 (v=0.81 kJ/KgK ;. Kace (p=K Cv solun - 3 p 2 31 = = 16 KI given kal Tz I sintropic compression 0.3 Ta 퓨 (16) 0.3 Tz (16) » Tz=684.62 k 298 Q2-21 (reat added at constant volum) .) = = 0.4x total = 0.4x 44,000 17,600 KJ/xg full CS Scanned with CamScanner Q2-2'

Queri = (ma+ma) Cv (T₂²T₂) = m17,600 (m + 1) Cv (T2 Tz) = 17,600 (23+1) (0.81) (T2-684.82) = 17,600 Ta'= 1589.96 = 1590k # Pressure rise Parameter, Pa' P2 Since V = Va' so 1590 684.62 Pr Tz 오는 2.3224 P2 V3 #Cut off ratio :-(S) = V₂' Q2-3= 0.6xQ. total = 0.6 x 49,000 = 26,400 Q2'-3 = 26,400 KJ /kg feel (matma) Cp (T3-T2') mtx 26,400 ma mf Cp (T3-T2') = 26,400 (2341) [Kcv] (To-To') = 26.400 CS Scanned with 2 4 x (1.330-81) (13 - 1590) = 26400 CamScanner

T3=2634.63K Since 2-3 is constant Pressure Prouss V3 T3 Ta' V3 2834.63 P = Va' 1590 S = 1.657 Ansuur CS Scanned with CamScanner