Describing the types of efficiencies in an IC ENGINE

1. ENGINE PERFORMANCE PARAMETERS
Designed by:
BHAWESH PRAJAPATI

2. 0
10
20
30
40
50
60
70
80
90
100
Fuel Indicated Power Brake Power
Percentage(%)
ENERGY FLOW
FRICTIONAL
LOSS
EXHAUST
COOLING
RADIATION
LOSSES

3. Indicated Thermal Efficiency
ith =
Indicated Power (W)
Energy of Fuel / sec.
Indicated Power(IP) = Power produced in cylinder
IP = (Pimep*l*a*n*k)/60 n=N/2
Energy of Fuel / sec. = ṁ * calorific value of fuel in KJ/KG

4. Brake Thermal Efficiency
bth =
Brake Power (W)
Energy of Fuel / sec.
BP(W) = (2*π*N*T)/60 , N = speed in rpm, T=torque(n-m)
Energy of Fuel / sec. = ṁ * calorific value of fuel in KJ/KG

5. Mechanical Efficiency
mech =
Brake Power (W)
Indicated power(W)
-LOSSES
Frictional Power(W) = Indicated Power – Brake Power

6. Volumetric Efficiency
volumetric =
Actual volume flow rate of air into intake
Volume displaced * N/2
Actual volume flow rate of air = ṁ/ρ
ṁ = mass flow rate(kg/sec)
ρ = Density of fluid
Energy of Fuel / sec. = ṁ * calorific value of fuel in KJ/KG

7. Mean Effective Pressure
Average pressure inside cylinder based on measured or calculated power output.
imep = Indicated mean effective pressure
bmep = Brake mean effective pressure
These both terms are used to compare the different engines.

8. Mean Speed of piston
Vp = Piston Speed (m/sec)
Vp = 2*L*N
L = Length of Stroke
N = Revolution per second (in crankshaft)

9. Specific fuel consuption
Fuel characteristics of engine = Kg/KWH
SFC = Fuel consumed per unit time = kg/hr = kg/kWH
Power
Depending upon power
bsfc = Brake fuel specific consumption
isfc = Indicated fuel specific consumption
Its inversely proportional to the thermal efficiency

10. Air-fuel ratio
Chemical correct or stoichiometric air fuel ratio (15:1)
Its just enough air for complete combustion of fuel
Equivalence ratio = Actual air fuel ratio
Stoichiometric air fuel ratio
Equivalence ratio < 1 --- Lean mixture
Equivalence ratio > 1 --- Rich mixture
SI (Petrol) – 11:1 to 20:1
CI (Diesel) – 18:1 to 80:1

11. Calorific value
Calorific Value of the IC Engine Fuels. The calorific value of the fuel is also
called as the heat value of the fuel. It is defined as the amount of heat released by
burning of unit quantity of the fuel.
HCV - If the fuel has higher calorific value it will have tendency to produce
more power in the engine.

12. THANKYOU
REFERENCE
1. www.google.com
2. www.wikipedia.com
3. Automobile Engineering Vol.1/Vol.2 (Dr. Kirpal Singh)