Diesel Engine

Inventor of Diesel Engine

                              Rudolf Diesel was born in the year1858 in Paris. His love for his work could be seen from the fact that an explosion of an engine almost took his life but did not deter him from his work. His engine was the first that provided evidence that fuel could be ignited without a spark.









Types of Diesel Engine

                         Diesel engines can be broadly distinguished as two-stroke and four-stroke. Bulky engines usually operate on the two-stroke cycle. Lighter engines generally operate on four-stroke cycle.
                          Generally cylinders are used in multiples of 2, 4, 6, or 8, .It doesn’t matter what number of cylinders are being used as long as the load on the crankshaft is counterbalanced to prevent excessive vibration. The inline-6 cylinder is used widely in medium and heavy duty engines.





Working of diesel engine.

                                       The temperature of gas rises when it is compressed. When the inlet valve opens air is sucked into the cylinder of a diesel engine due to vacuum created. The piston then moves upward and compresses air raising its pressure and temperature. As the piston moves up towards the end of compression stroke, injection of diesel fuel the combustion chamber that is cylinder takes place. There is high pressure inside cylinder so the fuel is injected through an atomizing nozzle at reasonably high pressure. The mixture of fuel and air then ignites and burns rapidly. The gas in the chamber expands. This forces the piston to move down and thereby producing power stroke. The connecting rod which is linked to crankshaft forces it to turn and delivers rotary power at the output end of the crankshaft. Scavenging of the engine is completed either by ports or valves.



Accessories of diesel engine


                                Turbocharger is a vital accessory and is used to compress the intake air. To increase the efficiency an after cooler/intercooler is used to cool the air after compression. Speed of the engine can be controlled using Governor by adjusting the rate of fuel delivery. In cold weather conditions these engines can prove problematic. To overcome this problem small electric heater called glow plug is used inside the cylinder to warm the cylinders prior to starting. While you can also have resistive grid heaters in the intake manifold to warm the inlet air until the engine reaches operating temperature. Engine heaters fixed into the utility grid are mostly used when an engine is shutdown for long period in cold weather to lessen the startup time and engine wear.











Comparison with gasoline engine :

                     Diesel engine is more efficient than gasoline engine as they have comparatively high compression ratio. Gasoline engine limitation is that it cannot be used for heavy duty applications as the components cannot withstand the stress caused on them. Diesel engines have longer life.
                      For the same power produced diesel engines are heavier compared to petrol engine.
                              
                      Diesel engine causes more pollution as compared to gasoline engines which are eco friendly. When compared on cost basis diesel engines prove to more expensive. Also diesel fuel is not easily available as gasoline. The noise and vibration produced by diesel engine makes them less popular.



Applications:

                             The diesel engines used today are more superior to Rudolf Diesel's original concept since lot of new research and developments have been done. They are used in trucks, ships, submarines, locomotives, and in electric generating plants. Most of the modern heavy road vehicles, large scale portable power generators, and most farm and mining vehicles have diesel engines.


         
                       Diesel engine continues to be most economical thermal engine till date. Even today diesel engine equipment is the first choice of any person looking at the difference in price and efficiency compared to gasoline. Lot of research work is going on to improve the efficiency and reduce the pollutants. The new diesel engine designs have advanced computer control that eliminates many of these disadvantages like noise, smoke, vibration and high cost. In the coming years, we are likely to see many more diesel engines vehicles on the road.