WHY DIESEL ENGINES HEAVIER AND MORE FUEL ECONOMICAL THEN PETROL ENGINES ?

PETROL AND DIESEL ENGINES

Basically diesel  and petrol  engines are most commonly  used in internal combustion engines, these both engines  operation  are seems similar, but some of interesting difference between  these both engines ,  each engine have a advantage over the other from  scientific  point  of view, by this topic will discussed  about those major  this of both diesel and petrol  engines.

WHAT IS BASIC OPERATION OF BOTH ENGINES  : 

Before going to main topic lets have to known basic operation of 4 stroke I C Engines, In the both engines have same four strokes that is intake ( suction ), compression, power and exhaust stroke,during  the in suction stroke  fresh air sucked in to cylinder, the compression stroke compress the this gas and produce hot gas then fuel is burn with hot gases then power stroke  happens next, remember power stroke is the only stroke where observe energy  from  fuel  last stroke will inject the burned gases to atmosphere.

BASIC OPERATIONS OF BOTH ENGINES

WHAT IS DIFFERENCE BETWEEN  PETROL AND DIESEL :

There difference  between the two engines due to different way of fuels burn in engines cylinder.

DEFERENCE BETWEEN DIESEL AND PETROL ENGINE

PETROL : Petrol  is a volatile fuel,  is readily evaporates so its get mixed with air, as a results just spark is sufficient to produce smooth combustion in a well premixed, engine.  Petrol has a very low flash point.Flash point  is the minimum temperature required for a liquid  fuel to form a spontaneous combustion mixture

DIESEL :  Diesel being a less volatile fuel doesn't not properly mix with air, diesel has a high flash point valve. However  if atomized diesel in high temperature air, spontaneous combustion will occur.

 

DIFFERENCE BETWEEN PETROL AND DIESEL ENGINES : 

In this petrol engine fuel and air pre mixed , while diesel engines, fuel and air mixing only during combustion, due to this reason diesel engines use a fuel injector while petrol use a spark plug. 

 

 WHAT IS MEANT BY THE DIRECT INJECTION  TECHNOLOGY : 

In this technology a spark plug is needed, The direct injection technology is just an another way of producing fine air fuel mixture. Instead  using a carburetor  to mix air and fuel the technology  uses fuel injector . The biggest advantage of direct injection technology is that fuel to be spayed can be controlled very accurately This will great fuel saving.

FOUR STROKE ENGINES INJECTION SYSTEM

INJECTION SYSTEM FOR MULTI CYLINDERS

INJECTION IN CHAMBER

WHY DIESEL ENGINE  ARE HEAVIER AND MORE FUEL  ECONOMICAL  ? 

Petrol  engines are less noisy and vibrate less compared to diesel  engines, this is because combustion process in premixed is smooth  and propagates well. But in diesel engine combustion could being any where in combustion chamber it turn out to be an uncontrolled process.
For this reason, to  reduce the excessive vibration  and noise  problems, diesel engines requires more structural design then petrol engines, To normalize  heavy unbalanced power production of diesel  engines heavy flywheel is needed. This is way petrol engines are always  prepared for light weight applications example  two wheeler and portable.

Diesel engine is compressing only the air, It may achieve better compression  ratio, without  risk of self ignition,  but premixed petrol engine such a high compression not possible, As we increase  compression  ratio of petrol  engine the mixture  become more porno engine , this is known as knocking. Over the period  of operation knocking  damage the engine parts.

The reason why diesel  car gives more mileage then a petrol car is due to the Difference  in the compression ratio. The better is the efficiency  of the cycle . A qualitative efficiency variation this is the reason  when diesel  engines have fuel economy  as compared to petrol  engines.

DIESEL IN PETROL  ENGINES :

Diesel in petrol engine will not even causes firing,the reason is simple. Diesel  is less volatile and will not mix with the air properly. In fact we will find it is impossible to make a good diesel-air mixture using  carburetor or direct injection  technology. This means if we apply spark to such a poor quality mixture ,it will not initiate any combustion.  

PETROL IN DIESEL  ENGINES :

An another question is if we put petrol in to diesel engines,in this process we are spraying a highly volatile fuel (petrol) in to chamber of highly compressed and hot air, This will lead to detonation rather then smooth combustion even actually the engine components will get damaged . More over diesel  generally acts as a good lubricants for the fuel pump and the injection  systems,when we put petrol into a diesel car making with intricate components to wear over the time. So that's a big no for petrol in diesel  engines.