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Consider the following statements: 1. Both Otto and Diesel cycles are special cases of dual combustion cycle 2. Combustion process in IC engines is neither fully constant volume nor fully constant pressure process 3. Combustion process in ideal cycle is replaced by heat addition from internal source in closed cycle 4. Exhaust process is replaced by heat rejection in ideal cycle Which of the above statements are correct?

Consider the following statements: 1. Both Otto and Diesel cycles are special cases of dual combustion cycle 2. Combustion process in IC engines is neither fully constant volume nor fully constant pressure process 3. Combustion process in ideal cycle is replaced by heat addition from internal source in closed cycle 4. Exhaust process is replaced by heat rejection in ideal cycle Which of the above statements are correct? Correct Answer 1, 2 and 4 only

In dual combustion cycle heat is added at constant volume and constant pressure and heat rejected at constant volume. In case of Otto cycle heat is added at constant volume and in Diesel cycle heat is added at constant pressure and rejected at constant volume in both the cycles so both Otto and Diesel cycles are special cases of dual combustion cycle.

Combustion, also known as burning, is the basic chemical process of releasing energy from a fuel and air mixture.  In an internal combustion engine (ICE), the ignition and combustion of the fuel occurs within the engine itself. The engine then partially converts the energy from the combustion to work. The engine consists of a fixed cylinder and a moving piston so combustion process in IC engines is neither fully constant volume nor fully constant pressure process.

Since, sometime interval is required for the chemical reactions during combustion process, the combustion cannot take place at constant volume. Similarly, due to rapid uncontrolled combustion in diesel engines, combustion does not occur at constant pressure

In the real cycles working on the gas cycles the exhaust process is there i.e. after the expansion of the gas the gases are exhausted into the air while in air-standard cycles the exhaust process is the heat rejection after the expansion process.

Internal combustion engine works in an open cycle, the working fluid is not recirculated back to the engine rather it is exhausted to the surrounding, therefore the working fluid does not undergo a thermodynamic cycle. Therefore for thermodynamic study air standard assumption are made for the analysis of the cycle.

 Assumptions:

The working fluid is an ideal gas

The specific heat are constant

The cyclic process is reversible

All the process are internally reversible

The combustion process is replaced by a heat-addition process from an external source

The exhaust process is replaced by a heat-rejection process and the gas returns to its initial state

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