What are the most differences ( advantages and disadvantages) between diesel and petrol engines?
is there any kind of diesel engines with dimensions less than petrol?
why petrol engines are not as expensive as diesel ones
Answer:
Advantages:
Diesel fuel is denser. Since the price per liter is generally less than petrol, the price per joule of energy is also less.
Diesel engines use a higher compression ratio. That makes them more efficient.
Diesel engines are also more efficient when running unloaded.
Higher efficiency means lower Carbon dioxide emission per distance traveled and weight hauled.
Diesel engines run in a lower speed range and produce more torque at lower speed making it easier to start heavy loads.
Diesel engines are generally built to last longer.
Disadvantages:
Diesel engines are heavier because of the higher compression and because they run slower and therefore need more torque and piston displacement to produce the same power.
Diesel engines are noisier.
They produce more soot emissions and burn fuel containing more sulfur, but this is currently being improved.
Diesel engines are more expensive because of the compression ratio and the size and weight.
The main difference is fuel efficiency.
Petrol (gasoline) engines burn a light hydrocarbon fuel which is ignited with an electric spark. The diesel relies on heat and pressure to ignite a heavier hydrocarbon fuel. Heavier fuel contains more chemical energy than lighter fuel. Also, the diesel does not need to generate electricity to operate. Because of this, the diesel burns less fuel compared to a gasoline powered engine. This helps to explain why most large vehicles which carry freight are powered by diesel engines, because it is more cost efficient. One other advantage of the diesel engine is that it has fewer moving parts. This makes the engine much more durable than a gasoline engine.
The major disadvantage of diesel is that it is hard to start in the winter. This is because the cylinders need to be warm enough to burn fuel. Also, the heavy diesel fuel can solidify when the temperature gets too low. This clogs the fuel line and stops the engine. Electric block heaters and fuel line warmers are used to overcome these problems.
Many "consumers" dislike deisel engines, despite their fuel efficiency. The diesel is much noisier and creates more vibration than a gasoline engine. Because of the way the fuel is burned, it also tends to form nitrate compounds, giving diesel exhaust its characteristic heavy, aromatic smell.
Diesel powered cars are more expensive because fewer of them are made. Volkswagon made a number of diesel models, the "rabbit" was probably the most popular. American cars tend not to be diesel because of a heavy reliance on gasoline. This might change in the future as "biofuels" are used more often. The diesel was designed to run on vegetable oil and most kerosine burning diesel engines can be easily modified to burn waste cooking oil. Some enterprising individuals fuel their vehicles by collecting the waste oil from chineese and fast food resteraunts.
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