The document provides an overview of basic thermodynamics concepts and the three laws of thermodynamics. It then discusses several thermodynamic processes including reversible and irreversible processes. It concludes with an explanation of the Rankine vapor power cycle, including its thermal efficiency calculation using the first law of thermodynamics.

1. Introduction

2. Basic Thermodynamics Concepts Heat. System. State. Path . Process. Cycle. Property .

3. Contd.. Process - Any change that a system undergoes from one equilibrium state to another is called a process . Path - The series of state through which a system passes during a process is called a path Cycle - A process with identical end states is called a cycle .

4. A review of basic thermodynamics: A refresher The ball represents mass exchange The arrow represents energy exchange

5. Zeroth Law of thermodynamics The Zeroth Law deals with thermal equilibrium and provides a means for measuring temperatures. Difference between thermal equilibrium and Thermodynamic equilibrium.

6. Zeroth Law of thermodynamics

7. First Law of thermodynamics The first law is the law of conservation of energy. The algebric sum of the work transfers is proportional to the algebric sum of heat transfer.

8. Limitations of First Law It does not place any distinction on the direction of the process under consideration. It will not help to predict, whether the system would undergo a change or no. It simply states that in a certain process heat and work are mutually convertible.

9. Second Law of thermodynamics The Second law of clausis states that It is impossible to construct a device that operates in a cycle and produces no effect other than the removal of heat from a body at one temperature and the absorption of an equal quantity of heat by a body at a higher temperature.

10. Second Law of thermodynamics contd.. The Second law of Max Planck’s states that It is impossible to construct an engine working on a cyclic process whose sole purpose is to convert all the heat supplied to it into equivalent amount of work.

11. Few Examples Some common examples. All processes in nature occur unaided or spontaneously in one direction. But to make the same process go in the opposite direction one needs to spend energy.

12. Third Law of Thermodynamics It is impossible by any procedure no matter how idealized, to reduce any system to the absolute zero temperature in a finite number of operations .

13. Summation of three laws You can’t get something for nothing To get work output you must give some thermal energy You can’t get something for very little To get some work output there is a minimum amount of thermal energy that needs to be given You can’t get every thing However much work you are willing to give 0 K can’t be reached.

14. Definitions of Reversible Process A process is reversible if after it, means can be found to restore the system and surroundings to their initial states. Some reversible processes: Constant volume and constant pressure heating and cooling -the heat given to change the state can be rejected back to regain the state

15. Reversible Process (contd…) Isothermal and adiabatic processes -the work derived can be used to compress it back to the original state. Elastic expansion/compression (springs, rubber bands)

16. Some Irreversible Process

18. Thermodynamic Processes A process in which the volume remains constant constant volume process. Also called isochoric process / isometric process A process in which the pressure of the system remains constant. constant pressure process. Also called isobaric process A process in which the temperature of the system is constant. constant temperature process. Also called isothermal process A process in which the system is enclosed by adiabatic wall. Adiabatic process

19. Rankine Vapor power cycle

20. T-s diagram Rankine power cycle

21. P-V diagram Rankine power cycle

22. Rankine Cycle contd… Process 1-2: Water from the condenser at low pressure is pumped into the boiler at high pressure. This process is reversible adiabatic. Process 2-3: Water is converted into steam at constant pressure by the addition of heat in the boiler. Process 3-4: Reversible adiabatic expansion of steam in the steam turbine. Process 4-1: Constant pressure heat rejection in the condenser to convert condensate into water. The steam leaving the boiler may be dry and saturated, wet or superheated. The corresponding T-s diagrams are 1-2-3-4-1; 1-2-3’-4’-1 or 1-2-3”-4”-1.

23. Thermal efficiency of rankine cycle Consider one kg of working fluid, and applying first law to flow system to various processes with the assumption of neglecting changes in potential and kinetic energy, we can write, δ q - δ w = dh For process 2-3, δw = 0 (heat addition Process), we can write, ( δ q )boiler= (dh )boiler =(h3-h2)