Lecture Note Definition Thermodynamics is derived from two words: ‘Thermo’ which means ‘Heat energy’ and ‘Dynamics’ which means ‘conversion’ or ‘transformation’ Concisely, thermodynamics is a division of science that deals with conversion of energy from one form to another The main forms of energy of interest in engineering thermodynamics are heat and work Definition contd. Work is the form of energy useful in displacement of a body Work Force Distance (Joules) Heat is the form of energy transferred due to temperature gradient between two bodies Heat Mass Specific Temperatur e difference (Joules) Applications of Engineering Thermodynamics Engineering application of thermodynamic principles is the design of various systems using fluid properties to cause energy transformation Applications in design of heat engines, refrigeration machines, air conditioning systems Scope of Thermodynamics It is limited to macroscopic properties of matter i.e. properties of large number of particles of systems It considers the initial and final states of a system and not the mechanism of the process Important fluid properties in thermodynamics Density Specific heat capacity Temperature Internal energy Entropy Enthalpy Pressure Specific volume Mass Fundamental concepts System Boundary Surrounding Open, Closed and Isolated Homogenous and heterogeneous Energy Kinetic energy Potential energy Internal energy Heat Engines Heat engines are devices designed for the purpose of converting other forms of energy (usually in the form of heat) to work. Heat engines differ considerably from one another, but all can be characterized by the following: 1. They receive heat from a high-temperature source (solar energy, oil furnace, nuclear reactor, etc.). 2. They convert part of this heat to work (usually in the form of a rotating shaft). 3. They reject the remaining waste heat to a lowtemperature sink (the atmosphere, rivers, etc.). 4. They operate on a cycle.