Question

DIESel Ehgine Power Plant) a) Write a short note (not more than 10 lines in each ase) Write a short note (not more than 10 lines in each case) for the following: () diesel engine, (ii) for Supercharger and turbocharger, (ii) Heat (energy) balance sheet of a Cooling system of a diesel power plant b) From the data given below, calculate: () indicated power, (i) brake power, and (ii) 20 minutes at full load. drawn heat balance sheet for a two-stroke diesel engine run for Revolution per minute (rpm) 350 Mean effective pressure (mep) = 3.1 bar Net brake load = 640N Fuel consumption 1.52 kg Cooling water 162 kg Water inlet temperature 30°C Water outlet temperature 55°C Air used/hg of fuel 32 kg Room temperature 25°C Exhaust temperature 305°C Cylinder bore 200 mm Cylinder stroke 280 mm Brake diameter1 metre Calorific value of fuel 43900 kJ/kg Steam formed per kg of fuel in the exhaust 1.4 kg Specific heat of steam in exhaust 2.09 kJ/ kg K Snacific heat of dry exhaust gases 1.0 kJ/kg K

Answer 1

1. Supercharger is an air compressor that increases the pressure or density of air supplied to an internal combustion engine. This gives each intake cycle of the engine more oxygen, letting it burn more fuel and do more work, thus increasing power. Power for the supercharger can be provided mechanically by means of a belt, gear, shaft, or chain connected to the engine's crankshaft.

Turbocharger is a turbine-driven forced induction device that increases an internal combustion engine's efficiency and power output by forcing extra compressed air into the combustion chamber. This improvement over a naturally aspirated engine's power output is due to the fact that the compressor can force more air—and proportionately more fuel—into the combustion chamber than atmospheric pressure. The key difference between a turbocharger and a conventional supercharger is that a supercharger is mechanically driven by the engine, often through a belt connected to the crankshaft, whereas a turbocharger is powered by a turbine driven by the engine's exhaust gas. Compared with a mechanically driven supercharger, turbochargers tend to be more efficient, but less responsive.

2. Heat balance sheet is an account of heat supplied and heat utilized in various ways in the system. Necessary information concerning the performance of the engine is obtained from the heat balance. The heat balance is generally done on second basis or minute basis or hour basis.It is shown in numerical-

3. Cooling system is provided because-

- the even expansion of piston in the cylinder may result in seizure of the piston.

- high temperature reduces strength of piston and cylinder liner.

- overheated cylinder may lead to pre-ignition of the charge in SI engine.

- physical and chemical changes occur in lubricant causes sticking of piston rings and excessive wear of cylinder.

Two methods of cooling are-

Air cooling

Liquid cooling
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