HIGH ALTITUDE PERFORMANCE OF DIESEL ENGINE

HIGH ALTITUDE PERFORMANCE OF DIESEL ENGINE

INTRODUCTION:

In day to day life there are many instances when it is required to operate engine at high altitude like air craft engines, marine engines operating at high altitude lakes, power generating diesel engines operating at high altitude regions etc.

A naturally aspirated engine will produce power in direct proportion to the density of the intake air. But air density decreases with altitude. At sea level, air has density of 1.2265 kg/m3. At 3050 meter altitude, the density drops to 0.9058 kg/m3.
This means as engine which delivered 100 kw at sea level will deliver

0.565
100 X----------
0.765

Thus there is a considerable power loss at high altitude. Therefore it is necessary to increase power of the engine at altitudes, without increasing weight and size of the engine. This can be done by supercharging/Turbo charging the engine.

Basically, in Supercharging and turbo charging same thing is done is different ways. In supercharging, the compressor which is mechanically driven by the engine itself compresses the incoming air.

Turbocharging is a particular form of supercharging in which compressor is driven by an exhaust gas turbine. Turbocharger utilize the exhaust energy of the engine and recovers a substantial part of energy which would otherwise go waste.

Major shortcomings of supercharging are :-

a) Pumps are driven by engine with mechanical drives but the mechanical drive is always a weak link.
b) The mechanical drive requires up to 20 % of the engine output. This offsets the gains made by supercharging. So turbo charging is preferred over supercharging.


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