Diesel cycle is called constant pressure cycle because the heat addition process in diesel cycle is done at constant pressure whereas petrol cycle is called constant volume cycle as here the heat addition is done at constant volume (Heat rejection in both the cycles is done at constant volume)
Why does the Diesel cycle have constant pressure?
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
Is Diesel cycle a constant pressure cycle?
In later years Diesel realized his original cycle would not work and he adopted the constant pressure cycle, which is known as the Diesel cycle Diesel cycle is one of most common thermodynamic cycles that can be found in automobile engines and describes the functioning of a typical compression ignition piston engine
What is constant pressure cycle?
The Diesel cycle is assumed to have constant pressure during the initial part of the combustion phase ( to in the diagram, below) This is an idealized mathematical model: real physical diesels do have an increase in pressure during this period, but it is less pronounced than in the Otto cycle
Which cycle is also called as constant volume cycle?
As is well known, the constant volume heat addition cycle, which is often referred to as the Otto cycle, considers one special case of an internal combustion engine, whose combustion is so rapid that the piston does not move during the combustion process, and thus combustion is assumed to take place at constant volume
Is diesel engine constant pressure?
In the diesel engine, air is compressed adiabatically with a compression ratio typically between 15 and 20 The ideal air-standard cycle is modeled as a reversible adiabatic compression followed by a constant pressure combustion process, then an adiabatic expansion as a power stroke and an isovolumetric exhaust
Why combustion is a constant pressure process?
At constant pressure the released heat by combustion is equal to the enthalpy variation (with work change) but at constant volume the released heat by combustion is equal to the system internal energy variation (without work change)
What is the difference between diesel and auto cycle?
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 the difference between Otto cycle and Diesel cycle?
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
Why petrol engines and diesel engines are called as SI and CI engines respectively?
in SI engines,ignition process is carried out with the help of a spark plug which ignites a mixture of air and fuel that is compressed in the combustion chamber Whereas,a diesel engine also known as Compression Ignition (CI) engine works on the basis of Diesel cycle or Constant pressure heat addition cycle
What is the difference between constant volume and constant pressure?
The volume of a gas is directly proportional to its temperature when pressure is constant The ratio of volume to temperature is constant when pressure is constant This relationship is known as Charles’ law or Gay-Lussac’s law a constant pressure process is said to be isobaric Summary P = absolute pressure V = volume
What is meant by diesel engine?
diesel engine, any internal-combustion engine in which air is compressed to a sufficiently high temperature to ignite diesel fuel injected into the cylinder, where combustion and expansion actuate a piston
What is cut off in diesel cycle?
What is cut-off in diesel cycle? 9-53C Cutoff ratio is the ratio of the cylinder volumes after and before the combustion process As the cutoff ratio decreases, the efficiency of the diesel cycle increases
Is also known as constant pressure cycle?
Explanation: Diesel cycle is also known as constant pressure cycle as pressure is constant in this cycle
Which of the following is known as constant pressure cycle?
Explanation: Otto cycle: The air-standard-Otto cycle is the idealized cycle for the spark-ignition internal combustion engines Otto cycle is the one which has two constant volume heat transfer processes and two adiabatic work transfer processes
Which is the engine also called as constant pressure cycle engine?
Otto cycle The Otto Cycle is named after Nikolaus Otto (1832–1891, German) who is credited as the first creator of a petroleum fuel based internal combustion engine operating under a four stroke cycle
Why is Otto cycle more efficient?
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
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, ie work delivered to wheels In general, engines using the Diesel cycle are usually more efficient, than engines using the Otto cycle
What is meant by Otto cycle?
An Otto cycle is an idealized thermodynamic cycle that describes the functioning of a typical spark ignition piston engine The Otto cycle is a description of what happens to a mass of gas as it is subjected to changes of pressure, temperature, volume, addition of heat, and removal of heat
Why jet engine is constant pressure?
When compared with Jet engine, the pressure in the Combustion Section of Jet Engine is almost constant, But before reaching Combustion Section (Through Compressor Air delivery) the pressure is made to increase with every stage of the compressors and the reason for this is to obtain high energy post combustion to Aug 13, 2018
Is a diesel engine internal combustion?
Diesel vehicles are similar to gasoline vehicles because they both use internal combustion engines In a compression-ignited system, the diesel fuel is injected into the combustion chamber of the engine and ignited by the high temperatures achieved when the gas is compressed by the engine piston
What is constant pressure and constant volume air standard cycle?
The Joule cycle is the air-standard cycle which describes the processes in the gas turbine The Joule cycle has constant pressure combustion and constant pressure heat rejection