Reversible and Irreversible process.pptx

Reversible and Irreversible changes.

1. Reversibility and irreversibility BY unknown .

2. CONTAINTS Introduction. Reversible process. Irreversible process. Concluson. Calculation.

3. Thermodynamics The branch of physical science that deals with the relations between heat and other forms of energy (such as mechanical, electrical, or chemical energy), and, by extension, of the relationships between all forms of energy. INTRODUCTION

4. Second law of thermodynamics gives more information about thermodynamics processes Second law may be defined as “Heat can not flow itself from colder body to hotter body” The second law is also used to determine the theoretical limits for the performance of mostly used Engineering systems like heat engine and heat pump. Second Law of Thermodynamics.

5. Reversible process It is defined as the one whose direction can be revered By an infinitesimal small change in some property of the system. It takes infinite time for completion Work obtained in these process is maximum.

6. Reversible processes require the absence of friction or other hysteresis effects. They must also be carried out infinitesimally slowly. Otherwise pressure waves and finite temperature gradients will be set up in the system, and irreversible dissipation and heat flow will occur. ΔSsurr=−qrevT .

7. ΔU=q+w Changes in entropy (ΔS), Together with changes in enthalpy (ΔH) w=PextΔV ΔU=Qrev+Wrev . For a process that reversibly exchanges a quantity of heat qrevqrev with the surroundings, the entropy change is defined as ΔS=qrev/T .

8. I rreversible process. Irreversible processes are actual processes carried out in finite time with real substances . In irreversible processes, mass transfer occurs through a finite chemical potential difference. No equilibrium in the system.

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10. How to calculate it ? work done is W=P(external)x change in volume. For an irreversible expansion process, a crude approximation to the force exerted by the gas on the piston (where the work is done) can be provided by the equation FA= Pext =nRTV−kVdVdt.

11. Conclusion A reversible process is one in which both the system and its environment can return to exactly the states they were in by following the reverse path. An irreversible process is one in which the system and its environment cannot return together to exactly the states that they were in .

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