The average indicated power in C.I. engine is $15kw/m^{3}$ of free air inducted per Minute. It is a four stroke engine having swept volume 3.4 liter. The speed of the engine is 3300 rpm and has a volumetric efficiency 80% referred to free air conditions of 1.013 bar and 22°C. It is proposed to provide with a blower, driven mechanically from the engine. The blower has the pressure ratio 1.8 and adiabatic efficiency 75%. It can be assumed that at the end of suction, in the supercharged condition, the cylinder contains a volume of air equal to the swept volume at the pressure and temperature of delivery from the blower. Calculate the net increase in break power. Take Mechanical efficiency of engine and blower as 80% .

I.P. = 15 kW/m 3 of free air

N =3300 rpm

V = 3.4 litre = $3.4 X 10^{-3} m^{3}$

$η_{v}$ = 80 % = 0.8

$p_{1}$ = 1.013 bar

$T_{1}$ = 22°C = 295 K

$η_{ad}$ = 75 % = 0.75

$η_{m}$ = 0.8

(i) Unsupercharged engine :

Swept volume/min,

Actual volume of air inducted,

(ii) Supercharged engine :

Blower delivery pressure,

Temperature of air after adiabatic compression in blower

Actual temperature of air after compression in blower,

It is given that the blower delivers the air equal to swept volume of $4.95 m^{3} /min$ at 1.8234 bar and 366.93 K.

Equivalent volume of air surrounding conditions of $p_{1}$ = 1.013 bar and $T_{1}$ = 295 K can be calculated as follows:

Increase in volume per min inducted into the cylinder

Increase in I.P. from air inducted

Increase in I.P. due to increased suction pressure

Total Increase in

Total Increase in

However, the increase in actual B.P. will be reduced due to the power required to drive blower. The blower power can be calculated as follows:

Mass of air delivered by blower,

Power required to run the blower,

Net increase in B.P. of the engine = Increase in B.P. – Power required to run the blower = 43.789 – 12.91

Net increase in B.P. of the engine = 30.88 kW