Sajjad Ahmed Memon S.S./ Health Physicist NIMRA 1 Sajjad Ahmed Memon S.S./ Health Physicist NIMRA

Sajjad Ahmed Memon Senior Scientist NIMRA Thermodynamics Sajjad Ahmed Memon Senior Scientist NIMRA

Sajjad Ahmed Memon S.S./ Health Physicist NIMRA Thermodynamics Thermodynamics is the study of the relationship between heat, work and the associated flow of energy. Any system, physical or chemical or even biological, if it utilizes energy, it can be considered as a thermodynamical system and the laws of thermodynamics can be applied to it. Sajjad Ahmed Memon S.S./ Health Physicist NIMRA

Sajjad Ahmed Memon S.S./ Health Physicist NIMRA Thermodynamics is the branch of science which deals with the interconversion of heat energy and mechanical energy. All those problems that are related to the interconversion of heat energy and work done are studied in thermodynamics. Sajjad Ahmed Memon S.S./ Health Physicist NIMRA

Sajjad Ahmed Memon S.S./ Health Physicist NIMRA To introduce the concepts of the thermodynamic, consider the simple example of a glass of hot water on a table. If the glass is not disturbed in any way, the temperature of the water slowly decreases till it reaches the temperature of the room. This is achieved by transferring heat energy from the hot water to the environment. Sajjad Ahmed Memon S.S./ Health Physicist NIMRA

Sajjad Ahmed Memon S.S./ Health Physicist NIMRA The glass of water is considered the system and the room is the environment. If Ts and Te represent the temperature of the system and the environment respectively, then Sajjad Ahmed Memon S.S./ Health Physicist NIMRA

Sajjad Ahmed Memon S.S./ Health Physicist NIMRA If Ts > Te , the heat will flow from the system to the environment. If Ts < Te , the flow of heat will be in the other direction. If Ts = Te then the system is said to be in equilibrium with the surroundings. The equilibrium in this case is a stable one and the temperatures remain equal, unless an external source disturbs one of them. Sajjad Ahmed Memon S.S./ Health Physicist NIMRA

Sajjad Ahmed Memon S.S./ Health Physicist NIMRA A process can be reversible or irreversible depending on whether or not it can trace back the same path to reach the initial state. A reversible process (considering the system and environment together) goes through infinitely small changes at an infinitely slow pace and is always at equilibrium. Sajjad Ahmed Memon S.S./ Health Physicist NIMRA

Sajjad Ahmed Memon S.S./ Health Physicist NIMRA Natural or biological processes almost always take place spontaneously and transfer energy from one part of the system to another in a short time and hence are not thermodynamically reversible processes. Sajjad Ahmed Memon S.S./ Health Physicist NIMRA

Sajjad Ahmed Memon S.S./ Health Physicist NIMRA System A thermodynamic system is a collection of matter which has distinct boundaries. OR A real or imaginary portion of universe which has distinct boundaries. OR A thermodynamic system is that part of universe which is under thermodynamic study. Sajjad Ahmed Memon S.S./ Health Physicist NIMRA

Sajjad Ahmed Memon S.S./ Health Physicist NIMRA

Sajjad Ahmed Memon S.S./ Health Physicist NIMRA For Example: A balloon filled with air A beaker filled with water Sajjad Ahmed Memon S.S./ Health Physicist NIMRA

Sajjad Ahmed Memon S.S./ Health Physicist NIMRA Types of System 1. Open System 2. Closed System 3. Isolated System. Sajjad Ahmed Memon S.S./ Health Physicist NIMRA

Sajjad Ahmed Memon S.S./ Health Physicist NIMRA Open System An open system is one in which both mass & energy transfer takes place across the boundaries. An open tank of water. Sajjad Ahmed Memon S.S./ Health Physicist NIMRA

Sajjad Ahmed Memon S.S./ Health Physicist NIMRA Closed System A closed system in which there is no transfer of mass takes place across the boundaries of system but energy transfer is possible. A gas in a balloon. Sajjad Ahmed Memon S.S./ Health Physicist NIMRA

Sajjad Ahmed Memon S.S./ Health Physicist NIMRA Isolated System An isolated system is that in which there is no transfer of mass & energy takes place across the boundaries of system. A thermo flask containing hot or cold liquid. Sajjad Ahmed Memon S.S./ Health Physicist NIMRA

Sajjad Ahmed Memon S.S./ Health Physicist NIMRA Carnot Engine Carnot engine is an ideal heat engine which converts heat energy into mechanical energy. Working: It consists of a cylinder and a piston. The walls of the cylinder are non-conducting while the bottom surface is the conducting one. The piston is also non-conducting and friction less. Sajjad Ahmed Memon S.S./ Health Physicist NIMRA

Sajjad Ahmed Memon S.S./ Health Physicist NIMRA Entropy It measures the disorderness of any system. Mathematically ΔS = ΔQ/T Where Δs shows change in entropy. Unit is Joule per degree Kelvin - J/°K. Sajjad Ahmed Memon S.S./ Health Physicist NIMRA

Sajjad Ahmed Memon S.S./ Health Physicist NIMRA Types of Entropy 1. Positive Entropy: If heat is supplied to the system the entropy will be positive. 2. Negative Entropy: When heat is rejected by the system the entropy will be negative. Sajjad Ahmed Memon S.S./ Health Physicist NIMRA

Sajjad Ahmed Memon S.S./ Health Physicist NIMRA