Table of Contents
- 1 Why is it called the air standard cycle?
- 2 What is an air standard dual cycle?
- 3 What is air standard efficiency of Otto cycle?
- 4 Why is the dual cycle known as a mixed cycle?
- 5 What is the difference between air standard cycle and fuel air cycle?
- 6 What is fuel air cycle What is its significance?
- 7 What type of cycle is used in a diesel engine?
- 8 What is the working principle of a diesel engine?
Why is it called the air standard cycle?
The dual-combustion cycle is shown in Fig. 3.15. The cycle gets its name because a proportion of the ‘combustion’ (heat addition) takes place at constant volume, from 2 to 3, and then the remainder occurs at constant pressure, from 3 to 4.
What is an air standard dual cycle?
Dual cycle, or limited pressure cycle, is a thermodynamic cycle that combines the Otto cycle and the Diesel cycle. In the dual cycle, combustion occurs partly at constant volume and partly at constant pressure. The thermal efficiency lies between Otto and Diesel cycle.
What is meant by air standard assumptions?
1- The working fluid is air, which continuously circulates in a closed loop (cycle). Air is considered as ideal gas. 2- All the processes in (ideal) power cycles are internally reversible. 3- Combustion process is modeled by a heat-addition process from an external source.
What is the main difference between the air standard models of the diesel and Otto cycles?
The main difference that separates these two cycles is the way they supply heat to the engine to begin the ignition. Another noteworthy difference is that the Otto cycle heat occurs at constant volume, whereas the diesel cycle works on constant pressure.
What is air standard efficiency of Otto cycle?
The maximum pressure in the engine is around 55.2 Mpa and thermal efficiency of engine is around 66.2\%.
Why is the dual cycle known as a mixed cycle?
In this cycle, part of heat addition occurs at constant volume while the rest is at constant pressure. The dual cycle is also called mixed or limited pressure cycle. This thermal efficiency can be converted in terms of measurable quantities as it was done for Otto and Diesel cycle.
What is the importance of dual cycle in Diesel engine?
Dual combustion cycle is an ideal air standard closed cycle, which has five processess where heat addition be firstly at constant volume and next at constant pressure and rejection at constant volume. This has application to use in Diesel engines.
What are the assumptions in dual cycle?
The working fluid is assumed to be a perfect gas. There is no change in the mass of the working medium. All the process that constitutes the cycle is reversible. Heat is assumed to be supplied from a constant high-temperature source and not from chemical reaction during the cycle.
What is the difference between air standard cycle and fuel air cycle?
The main difference between air-standard cycles (theoretical cycles) and fuel-air cycles is in the process of heat addition to the cycle. During the compression process in actual engines, heat exchange between the cylinder gases and the surroundings is continuously changing with time, both in magnitude and direction.
What is fuel air cycle What is its significance?
Answer: Compression ratio: * Ratio of fuel-air cycle efficiency to air standard cycle efficiency about constant for a given air- fuel ratio. * Maximum pressure and temperature increases with compression ratio, thus, efficiency improves. Effect of variables on engine performance 2. Therefore, higher efficiency.
What is the difference between Diesel cycle and Otto cycle?
The diesel cycle has comparatively higher compression ratio. It ranges from 11:1 to 22:1. It has lower thermal efficiency in comparison to Otto cycle. Due to high compression ratio, the fuel ignites on its own. After drawing air during the intake stroke, fuel is injected by an injector.
What is the difference between air standard cycle and dual cycle?
So this is the difference between the air standard cycles and the practical engines. This Dual cycle is a compromise between the Otto cycle and the Diesel Cycle. so it is called the mixed cycle or Limited pressure Cycle. The P-V and T-S diagram for the Dual cycle is shown below.
What type of cycle is used in a diesel engine?
Diesel engine operates on this cycle. This cycle also contains four processes,out of which two processes are adiabatic,third one is constant pressure process and forth process is constant volume process. Petrol or spark ignition engines use otto cycle while diesel or compression ignition engines use diesel cycle.
What is the working principle of a diesel engine?
Rudolph Diesel invented the diesel engine that is why the working principle is known as diesel cycle. In the diesel cycle, heat addition takes place at constant pressure. In the diesel cycle, heat addition takes place when the piston is retreating. The diesel cycle has comparatively higher compression ratio.