Thermodynamic Systems And Control Volume

The term thermodynamic system infers the definite amount of matter that is subjected to thermodynamic analysis. The system is defined by a boundary line beyond which it is referred as surrounding. For a thermodynamic system, mass is fixed and the boundary changes with time.

Control volume is the amount of matter and space bounded by the control surface which is the imaginary boundary (window) along the passage of the considered matter. For control volume, mass varies with time and

boundary (control surface) is fixed.

1. SYSTEM,BOUNDARY, SURROUNDINGS System -A thermodynamics system is defined a definite space or area on which the study of Energy Transfer and Energy conversions is made Boundary –The system and surrounding are separated by boundary. It may be fixed or movable or imaginary.It will not occupy any volume or mass in space

2. Surroundings - Anything outside the system which affects the behaviour of the system is known as surroundings Control volume – A specified large number thermal device has mass flow in and out of a system called as control volume Control surface – Both mass and Energy can cross the boundary of a control volume which is called control surface
3. CLASSIFICATION OF THERMODYNAMIC SYSTEM  Open system:-in open system, the mass as well as energy transfer may take place between system and its surroundings.  Most of Engineering devices are open system.
4. EXAMPLE OF OPEN SYSTEM:-  Internal combustion engines  Air compressor  Water pump  Steam engine  Boiler
5. CLOSED SYSTEM:- *In closed system, the mass with in the boundary of the system remains constant and only the energy transfer may take place between the system and its surroundings. Examples of closed system 1.Pressure cooker 2.A rubber balloon filled with air and tightly closed 3.The gas confined between a piston and cylinder
6. ISOLATED SYSTEM:- *In an isolated system,neither mass nor energy transfer takes place between the system and its surroundings. Examples of isolated system 1.Thermos flask 2.The universe
7. THERMODYNAMICS PROPERTY Property - It is defined as any measurable or observable characteristics of the substance when the system remains in equilibrium state.(ie) pressure, temp, density, volume, Energy, specific volume Intensive property - One whose value does not depend on the mass of the system, like temperature,pressure,density, specific volume, etc. (or) These properties are Independent on the mass of the system, these properties remain same Extensive property - One whose value depends on the mass of the system, like volume, total Energy, etc

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Homogeneous and heterogeneous thermodynamic systems

Homogeneous and heterogeneous thermodynamic systems A homogeneous thermodynamic system is defined as the one whose chemical composition and physical properties are the same in all parts of the system, or change continuously from one point to another. A homogeneous system can be exemplified by imagining a column of atmospheric air, which is a mixture of a number of gases, mainly nitrogen and oxygen. In a system of this kind, acted upon by the force of gravity, both the composition of the system and its physical properties will continuously change from one point to another. A heterogeneous system is denned as one consisting of two or more homogeneous bodies. The homogeneous bodies of a heterogeneous system are referred to as phases. Each phase is separated from other phases by interfaces, or boundaries, and in passing over such a boundary the chemical composition of the substance or its physical properties abruptly change. This phase boundary must not be regarded as a math

Macroscopic and Microscopic viewpoint.

Macro simply means big or large and micro refers to nano,small or tiny thus viewpoints refers to the perceptive through which an observer witnesses it's surrounding,this term is totally relative as an example:- The planet earth is extremely big as compared to a some stone on a beach but it is extremely small as compared to the sun thus for an observer the macro and micro viewpoints changes with relativity. Macroscopic Approach: In this approach a certain quantity of matter is considered without taking into account the events occurring at molecular level. In other words this approach to thermodynamics is concerned with gross or overall behaviour. This is known as classical thermodynamics. The analysis of macroscopic system requires simple mathematical formula. The value of the properties of the system are their average values. For examples consider a sample of gas in a closed container. The pressure of the gas is the average value of the pressure exerted by millions

Quasi-Static Process

Consider a system of gas exists in a cylinder. The piston consists of many very small pieces of weights. Initially system is in an equilibrium state. When the gas system is isolated, the weights on piston are removed one by one slowly, at any instant of upward travel of the piston. So every state passes through by the system will be in an equilibrium state. Thus the system passes through the locus of all equilibrium points. This infinitely slow system is a quasi-static process. If the same small weights are now placed slowly one by one on top of the piston then the process will reverse in the same manner. When a process is processing in such a way that system will be remained infinitesimally close with equilibrium state at each time, such process will be termed as quasi static process or quasi equilibrium process. In simple words, we can say that if system is going under a thermodynamic process through succession of thermodynamic states and each state is equilibrium state th

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