Answer to Question #281074 in Mechanical Engineering for Emil

Question

Air is used as a working substance in a given internal combustion engine, which is

supplied with heat at a constant volume. Based on the data, calculate the following:

1)Pressure and temperature of the ending of isentropic expansion.

2)Pressure rise rate

3)Thermal efficiency of the cycle

4)The work of the cycle

5.The average pressure of the cycle

Givens:

k=1.4

r=10

T 1 =285 K

T 3 =2274 K

p 1 =1.013 bar

v 1 =0.5 m 3 /kg

Answer 1

In the Air-Standard Diesel cycle engine the heat input Q_in occurs by combusting the fuel which is injected in a controlled manner, ideally resulting in a constant pressure expansion process 2-3 as shown below. At maximum volume (bottom dead center) the burnt gasses are simply exhausted and replaced by a fresh charge of air. This is represented by the equivalent constant volume heat rejection process Q_out = -Q_4-1. Both processes are analyzed as follows: