Because diesel has a higher compression resistance — because it is denser than light distillate fuels — engineers can design and develop diesel engines with higher compression ratios than gasoline engines. The higher the compression ratio of an engine, the greater the thermal efficiency.
Why do diesel engines have higher thermal efficiency?
High Oxygen to Fuel Ratio
The second reason that diesel engines have a higher thermal efficiency than gasoline engines is that of the oxygen to fuel ratio. The greater the amount of air in an air-to-fuel ratio, the cleaner the fuel burns and the more energy it produces.
Which engine has higher thermal efficiency?
Real diesel engines are of course considered to be more efficient that Otto cycle engines; one reason being that diesel engines typically operate at higher compression ratio and the expansion ratio from even the later stages of heat release can still be considerably higher than that of most real Otto cycle engines.
What is the disadvantage of diesel engine?
Cons of diesel cars
Diesel fuel usually costs more. Servicing can be more expensive, although you don’t need to do it as often. Diesel cars produce a lot more NO2. Diesel engines can be slightly noisier.
Which engine has long life petrol or diesel?
Diesel engines do last longer than petrol ones. Diesel is a light oil and when burned and used as fuel by the vehicle it lubricates the parts of the engine. This prolongs the life of the engine. Petrol is a detergent and washes away oil from the components of the engine, therefore, wearing it out quicker.
What is the efficiency of diesel cycle?
A typical diesel automotive engine operates at around 30% to 35% of thermal efficiency. About 65-70% is rejected as waste heat without being converted into useful work, i.e. work delivered to wheels. In general, engines using the Diesel cycle are usually more efficient, than engines using the Otto cycle.
How can we increase thermal efficiency of diesel engine?
As a result, thermal efficiency was improved owing to the combined increase in injection pressure, advanced injection timing, and split-main injection. According to the analysis of heat balance, a larger amount of the second part of the main injection decreased the cooling loss and increased the exhaust loss.
What increases the diesel engine?
As well as the high level of compression allowing combustion to take place without a separate ignition system, a high compression ratio greatly increases the engine’s efficiency.
Which fuel is most efficient?
Diesel engines generally achieve greater fuel efficiency than petrol (gasoline) engines. Passenger car diesel engines have energy efficiency of up to 41% but more typically 30%, and petrol engines of up to 37.3%, but more typically 20%.
How many liters per 100km is fuel efficient?
In general, 5 to 8 litres per 100 km would be considered a good fuel efficiency, 8 to 12 litres per 100 km would be average, and more than 12 litres per 100 km would be considered a relatively low fuel efficiency.