INTRODUCTION (1 CLASS)
•Thermodynamics= Thermo+dynamics.•Thermo stands for various kinds of energy such as heat, electricity, light, solar, steam.
•Dynamics stands for energy in transitional state.
•Possible changes in physical properties of substances.
1) increase and decrease in temperature.
2) increase and decrease in temperature.
•Thermodynamics is the science of energy transfer and it's effect on physical properties of substances.
•Carnot's Theory- Reflections on the motive power of fire.
CLASS-2
Defination of thermodynamics
It is a science of energy transfer and it's effect on physical properties of substances such as temperature, volume, density.
Application
Nuclear Power plant, chemical process plant, air conditioning, internal combustion engine, gas dynamics, etc.
Macroscopic and Microscopic viewpoint
a) Macroscopic-
•Macro stands for large.
•In macroscopic approach, certain quantities of material is considered and we don't consider the events taking place at molecular level.
Ex- Pressure
•Here, we consider gross or overall behaviour.
•We do not consider the action of individual molecules.
•Only a few properties are required to describe, i.e, Temperature, Pressure, Volume, Viscosity, Density.
•Value of the property is there average value.
Ex- Pressure
•The changes in properties can be felt by our senses.
•It requires simple mathematical formula in order to analyse them.
•It is called classical thermodynamics.
b) Microscopic-
•Micro stands for small.(Particles which can't be seen from naked eyes)
•It is study in which molecular level events are absorbed.
•Continuum- A system which appears to be continuous due to the closely packing of particles but in reality they are not continuous.
•Each molecule position, velocity, energy is considered.
•Also known as stastical thermodynamics.
•These properties are continuously changing with time.
•Large number of variables are required to describe the system. This makes the analysis complicated.
•Properties like velocity, momentum, kinetic energy can't be easily measured. It requires sophisticated instruments.
•Our senses can't fell changes in the properties.
•Advanced statistical and mathematical methods are needed to explain the changes in the system.
•It is called statistical Thermodynamics
CLASS-3
System
•Quantity of matter or a region in space where attention is concentrated.
•Types of system
1)Closed system-
•System of fixed mass.
•No mass transfer takes place.
•Energy can come in and go out.
2)Open system-
•Mass and energy both can come in and go out.
3)Isolated system- No energy and mass transfer takes place.
Control Volume and Control Surface(C.V./C.S.)
•Most of the engineering systems are open systems.
•Volume focused for thermodynamic studies is known as Control Volume, bounded by a surface called Control Surface.
•Matter as well as energy crosses the control surface.
Thermodynamic properties, processes and cycles
1) Properties
•Properties are characteristics of a system from which it's physical conditions can be described.
•Properties are macroscopic in nature.
•Example- Temperature, Pressure, Volume, etc.
•Properties are of two types-
a)Intensive Properties-
•Independent of the amount of material in the system.
•They are not additive.
•Examples- Pressure, Density, Temperature, Viscosity, Surface Tension, Dipole Moment, Dielectric Constant, Concentration, Refractive index, electromotive force, chemical potential, Mole fraction, Freezing Point, Boiling Point.
b) Extensive Properties-
•These are proportional to the mass of the system.
•These are additive.
•Examples-Mass, Volume, Heat Capacity, Internal Energy, Enthalpy, Entropy, Gibb's Free Energy.
2)Process-
•When the path is completely specified then change in state is called process.
•Any operation in which one or more of the properties of a system changes is called a change of state.
Homogeneous and Heterogeneous systems
•A quantity of matter homogeneous throughout in chemical composition and physical structure is called a phase.
•Every substance can exists is one of three phases
a)Solid
b) Liquid
c)Gas
•A system consisting of a single phase is called a homogeneous system.
•A system consisting of more then one phase is known as a heterogeneous system.
Examples and Problems
Comments
Post a Comment