1. S.Y. B. Tech. ( Production )
Applied Thermodynamics and Heat Engines
Assignment – 5
Internal Combustion Engines
1. Plot the Otto and Diesel cycles on P-V and T-s charts. Derive the equations for the
thermal efficiency of both the cycles. Hence show, why the efficiency of Otto
cycle is more than that of the Diesel cycle, for the given compression ratio.
2. Explain the Valve Timing Diagram for four – stroke as well as two – stroke
engines.
3. Compare the S.I. Engines with C.I. Engines.
4. A four – cylinder four – stroke cycle spark ignition engine develops a maximum
brake torque of 160 N-m at 3000 RPM. Calculate the engine displacement, bore
and stroke. The brake mean effective pressure at the maximum torque point is 960
kPa. Assume bore is equal to stroke.
( Solved example from Rajput, 6 ed., Example 23.8, pg 1113 )
5. A four – cylinder two – stroke cycle petrol engine develops 30 kW ant 2500
RPM. The mean effective pressure on each piston is 8 bar and mechanical
efficiency is 80 %. Calculate the diameter and stroke of each cylinder for the
stroke : bore ratio of 1.5. Also calculate the fuel consumption of the engine, if the
brake thermal efficiency is 28 %. The calorific value of the fuel is 43,900 kJ / kg.
( Solved example from Rajput, 6 ed., Example 23.22, pg 1123 )