Mechanical Engineering - Thermodynamics - Discussion

1) In the irreversible process the initial state of the system and surroundings cannot be restored from the final state.

2) During the irreversible process the various states of the system on the path of change from initial state to final state are not in equilibrium with each other.

3) During the irreversible process the entropy of the system increases decisively and it cannot be reduced back to its initial value.

4) The phenomenon of a system undergoing irreversible process is called as irreversibility.

Constant pressure, constant volume & polytropic process may be reversible & irreversible also.

In all the processes there is heat transfer to or from the system. Now if the heat transfer takes place across finite temperature difference then the process is externally irreversible.

Furthermore if there is frictional dissipation then the system is internally irreversible.

I think the irreversible one is only the polytropic process because there is no usage of polytropic processes at ideal cycles like carnot, otto, diesel, but we used pressure and volume process at these cycles so here my question is the otto and diesel cycles are reversible or not if they are irrversible then the cont pressure and cont volume also irrevesible.

Answer is correct only adiabatic process is reversible, at constant pressure, constant volume there is loss of heat and if their is heat transfer how can it be reversible. Reversible process means at end of the process it come back to its original state so when it will come? when their is no loss of heat.

False is correct. Because there is constant pressure process, it means pressure at state point 1 is equal to pressure at state point 2. So there is no energy loss. Similarly this concept is applicable to constant volume process also. So it is reversible process.

These processes are either reversible or irreversible.

Reversible processes are one which returns to its original state without leaving any effect on the surrounding.

As per Khurmi, the correct answer is TRUE.

Practically they are irreversible but are considered Internally reversible like in reciprocaing engine. And that's why equation is defined for them and also these processes are shown by solid lines in diagrams.

1. All are the process such as constant volume, constant pressure, isothermal Or constant temperature (pv=C), adiabatic & polytropic are all reversible processes.

2. Throttling is an irreversible process.

Reversible process is one in which path of the process is known. And when equation for a process is defined that means path is also defined. So answer is false they all are reversible process.

In the constant pressure process only pressure remains same in both the states and other parameters change. So obviously it is not a reversible process. Similar for all the cases.