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They aren't.
Gasoline engines are (sort-of) constant volume engines while Diesel engines are (sort of) constant pressure engines.
In a gas engine, the combustion process is so fast compared to the travel rate of the piston that it all happens in the same volume, before the piston has had much time to move away.
In a Diesel engine combustion is so much slower that the piston will actually have time to move away while fuel is still being burnt.
As the volume of the combustion chamber increases during burn as the piston moves away, the pressure will remain pretty much the same throughout the burn.
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∙ 11y ago
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Why petrol engines called constant volume engines?
In a engine, well 99.9% of them the piston is conected to a crank via a conrod, as nothing changes during the strokes of the piston and the cylinder bores dont change. The swept volume of the stroke is always constant.
What is the difference between four stroke petrol engine and that of diesel engine?
Petrol engines are sometimes also called constant volume engines. They suck in a combustible mixture of fuel and air, compress it and then ignite it with a spark plug. Combustion is so fast that (most of it) takes place while the volume of the compression chamber(in the cylinder, between piston and cylinder head) stays the same. Then, as the piston moves away from Top Dead Center (TDC) combustion is (mostly) done and the pressure begins to drop. Diesel engines are also called constant pressure engines. They take in air, compress it to the point where the temperature alone will ignite the fuel, and then they inject the fuel. And fuel keeps being injected and burned as the piston moves away from TDC, keeping the pressure, kinda-sorta constant through the combustion phase.
Differences between petrol and diesel engines?
sic difference between Petrol and Diesel engines that the difference of fuel and their mixture..in diesel we only compresses the Air and sprays Diesel but in Petrol Engines we compresses both the air and Petrol together and gets burnt with the the help of spark given by the Spark plug. I must add this, also the thermodynamic cycle is so different in diesel engines rather than petroleum engines. You can fined more in Reed's series volume 12
Dual combustion cycle?
From Wikipedia, the free encyclopedia Dual Combustion Cycle (also known as the limited pressure or mixed cycle, Seiliger cycle or Sabathe cycle) is a thermal cycle that is a combination of the Otto cycle and the Diesel cycle. Heat is added partly at constant volume and partly at constant pressure, the advantage of which is that more time is available for the fuel to completely combust. Because of lagging characteristics of fuel this cycle is invariably used for diesel and hot spot ignition engines. The dual cycle consists of following operations: # Adiabatic compression # Addition of heat at constant volume. # Addition of heat at constant pressure. # Adiabatic expansion. # Rejection of heat at constant volume.
What is the difference between otto cycle and diesel cycle?
the difference is the heat addition type In Otto Cycle the heat addition is Isochoric ((constant volume)) In Diesel Cycle the heat addition is Isobaric ((constant pressure))
What is constant volume?
The constant Volume process, also known as Isovolumetric, is where the volume is constant and does not change. In a P, V, Diagram this should be where volume is constant where Pressure is increased. The work done (area under the curve) would be = to 0 in this case.
Why does the heat is added at constant volume in Otto cycle and at constant pressure in Diesel cycle?
in otto cycle the burning of fuel is instantaneously therefore a very small voulme is required for burning of fule
What does diesel mechanics do?
Diesel mechanics is the knowledge to design, build, and mantain, diesel engines. This type of internal combustion engine works on a thermodynamical cycle called Otto Cycle of Four Stages for Diesel, which has a different behavior of that one followed by the gasoline engines, the latter called Otto Cycle of Four Stages (for gasoline). Diesel is a fuel with higher octane than gasoline, to the point where the use of a spark to ignite the fuel/air mix turns pointless, so the spark plug is ommited and the mix is instead ignited by cylinder compression, making the mix to heat due to drastic pressure increased and volume reduced.
What is the compression ratio of and engine?
Compression ratio is the difference in the volume of a engine cylinder between when the cylinder is at it's largest volume, compared against when the cylinder is at it's smallest volume. Gasoline engines use 8:1 to 12:1 compression ratio. Diesel fuel engines use 14:1 to 25:1.
How does the volume and pressure change in a tire after a long drive?
The volume is constant. The pressure will increase.The volume is constant. The pressure will increase.
How do I work out the Cubic volume of diesel?
Of diesel fuel?
How may liquids be described in terms of shapes and volume?
A solid has a constant volume and a determinate shape.A liquid has a constant volume but an indeterminate shape.A gas has an indeterminate volume and an indeterminate shape.liquids have a constant volume at a constant temperature, and take the shape of their container.
