Diesel Cycle

Diesel cycle is named after Rudolph Diesel (1858- 1913), a German engineer).

This cycle is used to approximate the operation of a compression ignition (C.I.) internal combustion engine.

Process                                    Description

1 – 2                             Reversible adiabatic compression.

2 -3                              Constant pressure heat addition.

3 – 4                             Reversible adiabatic expansion.

4- 1                              Constant volume heat rejection.

Let 1 kg of ideal gas circulate in the cycle.

10.4.1 Derivation of Air Standard Efficiency of Diesel Cycle

Q s  = c p (T3 –T2)

Q R = c u (T4 – T1)

Process 2 – 3

P2 / u2 / T2 = P3 u3 / T3

T3 = T2 (u2 /u2) – T2 β

T3 = T1 β r γ-1

Process 3-4

Inserting the values of T2, T3 and T4 in terms of T1 from equations (10.6), (10.7) and

(10.8) to equation (10.5) we get

10.4.2 Mean Effective Pressure (Pm)

It is easier to find out w net from q s – q R than by area under the curve since w net = w 2 -3 + w3 -4 – w1 – 2 which leads to chances to commit mistakes.