The Otto cycle has less compression ratio (7:1 to 10:1) but in diesel cycle the compression ratio is high (11:1 to 22:1). In Otto cycle as well as in diesel cycle heat rejection takes place at constant volume. The efficiency of Otto cycle
is less
as compared with the Diesel cycle.
Which is more efficient diesel engine or Otto engine?
In practice,
Diesels
are more efficient than Otto engines, because the latter must operate at lower compression ratios to avoid knocking (Section 3.6).
What is the difference between the Otto cycle and the Diesel cycle explain why the higher efficiency of the Otto cycle compared to the Diesel cycle for the same compression ratio is not a result of practical importance?
6 Diesel Cycle
Although for a given compression ratio the Otto cycle has higher efficiency, because
the Diesel engine can be operated to higher compression ratio
, the engine can actually have higher efficiency than an Otto cycle when both are operated at compression ratios that might be achieved in practice.
Which cycle is best Otto or Diesel?
Comparing efficiency to Otto cycle
Comparing the two formulae it can be seen that for a given compression ratio (r), the ideal Otto cycle will be more efficient. However,
a real diesel engine will
be more efficient overall since it will have the ability to operate at higher compression ratios.
What is the difference between the Otto cycle and the Diesel cycle?
Otto cycle is used for petrol or spark ignition engine while diesel cycle is used for diesel or compression ignition engine. The main difference between Otto cycle and Diesel cycle is that
in Otto cycle heat addition takes place at constant volume and in diesel cycle heat addition takes places at constant pressure.
What is Diesel cycle efficiency?
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.
What is K in Otto cycle?
Thermal Efficiency Derivation
A typical value for an air/fuel mixture is
k = 1.35
.
What is ideal Otto cycle?
In the ideal Otto cycle the fuel-air mixture is introduced during the induction stroke and compressed to a much lower compression ratio (around
8:1
) and is then ignited by a spark. The combustion results in a sudden jump in pressure while the volume remains essentially constant.
Is a diesel engine a heat engine?
A diesel engine is
a type of internal combustion heat engine
, powered by diesel. These engines run small electric generators called diesel generators, often in remote areas as well as the engines of cars and trucks (both large and small).
What is the biggest engine in the world?
The Wärtsilä RT-flex96C
is a turbocharged, two-stroke reciprocating diesel engine designed to power large container ships and is the world’s largest engine.
Which cycle is used in diesel engine?
The diesel engine is an intermittent-combustion piston-cylinder device. It operates on either a
two-stroke or four-stroke cycle
(see figure); however, unlike the spark-ignition gasoline engine, the diesel engine induces only air into the combustion chamber on its intake stroke.
What is Otto cycle with diagram?
The idealized diagrams of a four-stroke Otto cycle Both diagrams: the intake (A) stroke is performed by an isobaric expansion, followed by an adiabatic compression (B) stroke. … The cycle is closed by the exhaust (D) stroke, characterized by isochoric cooling and isobaric compression processes.
Why is there constant pressure in a diesel cycle?
The reason, for constant pressure heat addition in a diesel cycle is that,
when the fuel is injected into the compressed air inside the cylinder, question of maintaining a constant volume vanishes
. We are adding more volume and igniting the mixture as heat addition. Hence, a constant volume is not possible.
Which fuels can an Otto engine run on?
The Otto Cycle engine was eventually adopted to run on Ligroin and eventually
gasoline, and many gases
. During WWII Otto engines were run on more than 62 different fuels, such as wood gas, coal gas, propane, hydrogen, benzene, and many more. The engine is limited to light fuels.
What is Carnot cycle Otto and Diesel cycle?
It is found that for a fixed temperature ratio that the
efficiency increases
with compression ratio for the Otto, Brayton and Diesel cycles until their efficiency is the same as that of the corresponding Carnot cycle. This occurs at the point where the heat input to the cycles is zero.
How does Otto engine work?
The Otto cycle engine uses
a spark to ignite a mixture of air
and – traditionally – gasoline
2
compressed by the piston within the engine cylinder. This spark ignition causes an explosive release of heat energy which increases the gas pressure in the cylinder, forcing the piston outwards as the gas tries to expand.
