1. ENGINEERING THERMODYNAMICS Dr. M.R.SWAMINATHAN Assistant Professor Internal Combustion Engineering Division Department of Mechanical Engineering ANNA UNIVERSITY CHENNAI-25.

2. LIMITATIONS OF I LAW The first law of thermodynamics is simple, general, but does not constitute a complete theory because certain processes it permits do not occur in nature!

3. Examples of processes which are not prohibited by the first law, but cannot happen in a real world. Perfect machine Transfer heat from cold to hot subject Gas expansion

4. IRREVERSIBLE PROCESSES 1.A battery discharges through a resistor, releasing energy. The reverse process will not occur. 2.Two gases, initially in separated adjoining chambers, will mix uniformly.

5. 3.A free expansion of gas (in Gay- Lussac-Joule experiment) 4.Heat flows from a high temperature body to a low temperature reservoir in the absence of other effect

6. STATEMENTS OF THE SECOND LAW OF THERMODYNAMICS: Kevin-Planck Statement: It is impossible to construct a device that operates in a cycle and produces no other effects than the performance of work and the exchange of heat with a single reservoir.

7. Model Heat Engine Q hot = W+Q coldQ hot = W+Q coldor Q hot -Q cold =WQ hot -Q cold =W (what goes in must come out)

8. II LAW OF THERMODYNAMICS

9. EFFICIENCY OF HEAT ENGINE

10. Even the most efficient heat engines reject almost one- half of the energy they receive as waste heat.

11. It is impossible for any device that operates on a cycle to receive heat from a single reservoir and produce a net amount of work.

12. Clausius Statement: It is impossible to construct a device that operates in a cycle and whose sole effect is to transfer heat from a cooler body to a hotter body.