Thermodynamics Notes - Chapter 1 BASIC CONCEPTS AND...

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Chapter 1 BASIC CONCEPTS AND DEFINITIONS Thermodynamics is the science of energy transfer which deals with the relations among heat, work and properties of systems. The name ‘thermodynamics’ is derived from the Greek words therme, meaning ‘heat’ and dynamis meaning power. Thus, thermodynamics is basically the study of heat and power. 1.1 Application Area of Thermodynamics Energy transfer is present in almost all the engineering activities. Hence, the principles of thermodynamics are playing vital role in designing all the engineering equipments such as internal combustion engines, rockets, jet engines, thermal and nuclear power plants, refrigerators etc. 1.2 Statistical and Classical Thermodynamics Statistical Thermodynamics is microscopic approach in which, the matter is assumed to be made of numerous individual molecules. Hence, it can be regarded as a branch of statistical mechanics dealing with the average behaviour of a large number of molecules. Classical thermodynamics is macroscopic approach. Here, the matter is considered to be a continuum without any concern to its atomic structure. Consider a gas in a container. Pressure exerted at the wall of the container is the average force per unit area due to the collision of the gas molecules on the wall surface. To determine this pressure, we need not know the behaviour of individual molecules of the gas. This approach is macroscropic approach. However, the results obtained from macroscopic and statistical study of matter. 1.3 Thermodynamic Systems and Surroundings A Thermodynamic system is defined as a quantity of matter or a region in space whose behaviour is being investigated. Everything external to the system is defined as surroundings. In its usual context the term ‘surroundings’ is restricted to the regions in the immediate vicinity which has a detectable influence on the system. Boundary is the surface which separates the system from its surroundings. It may be fixed or moving and real or imaginary. 1
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1.3.1 Types of Thermodynamic Systems There are three types of thermodynamic systems : a) Closed System b) Open System and c) Isolated System In closed system, attention is focused on a fixed mass. Energy in the form of heat and work ( The terms heat and work will be defined in the chapter 2. ) can cross the boundary of the system. But there is no mass flow across the boundary. Hence, the possibility of change in volume is always there in the closed systems. Fig.1.2 Closed system In open system, both matter and energy can cross the boundary. Here, the behaviour of a fixed region in space called control volume is investigated and hence, there is no change in volume. The surface of the control volume is known as control surface. Fig.1.3 Open system
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This note was uploaded on 09/16/2011 for the course MECHANICAL 101 taught by Professor Jskushawaha during the Spring '11 term at Indian Institute of Technology, Chennai.

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Thermodynamics Notes - Chapter 1 BASIC CONCEPTS AND...

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