The quantities in this equation, evaluated at stoichiometric conditions are fuel 0. pTT Muddy points Ho △ h., calculated?(MP2A1) What are"stoichiometric conditions"?(MP 2A.2 2. 4.2. Diesel cycle The Diesel cycle is a compression ignition(rather than spark ignition)engine. Fuel is sprayed into the cylinder at P,(high pressure)when the compression is complete, and there is ignition without a spark. An idealized Diesel engine cycle is shown in Figure 2A-3 Adiabatic Figure 2A-3 Ideal Diesel cycle The thermal efficiency is given by eL C,(T-T) (T This cycle can operate with a higher compression ratio than otto cycle because only air is compressed and there is no risk of auto-ignition of the fuel. Although for a given compression ratio the Otto cycle has higher efficiency, because the Diesel engine can be operated to higher compression ratio, the engine can actually have higher efficiency than an Otto cycle when both are operated at compression ratios that might be achieved in practice 2A-42A-4 The quantities in this equation, evaluated at stoichiometric conditions are: ˙ ˙ , m m 1 15 h c T 4 10 10 288 fuel fuel p 1 7 3 ≈ ≈ × × ∆ so, ˙ ˙ W mc Tp 1 r 1 9 1 1 ≈ −     γ − . Muddy points How is ∆ h fuel calculated? (MP 2A.1) What are "stoichiometric conditions"? (MP 2A.2) 2.A.2. Diesel Cycle The Diesel cycle is a compression ignition (rather than spark ignition) engine. Fuel is sprayed into the cylinder at P2 (high pressure) when the compression is complete, and there is ignition without a spark. An idealized Diesel engine cycle is shown in Figure 2A-3. QH P V2 V V3 V4 = V1 QL Adiabatic reversible 2 3 4 1 Figure 2A-3 Ideal Diesel cycle The thermal efficiency is given by: η η γ Diesel L H v p Diesel T T T T Q Q CT T CT T T T =+ =+ ( ) − ( ) − = − ( ) − ( ) − 1 1 1 1 1 1 4 3 2 1 4 1 2 3 2 This cycle can operate with a higher compression ratio than Otto cycle because only air is compressed and there is no risk of auto-ignition of the fuel. Although for a given compression ratio the Otto cycle has higher efficiency, because the Diesel engine can be operated to higher compression ratio, the engine can actually have higher efficiency than an Otto cycle when both are operated at compression ratios that might be achieved in practice