Thermodynamics
Thermodynamics can be defined as the science of energy. Although everybody has a feeling of what energy is, it is difficult to give a precise definition for it. Energy can be views as the ability to cause changes.
One of the most fundamental laws of nature is the conservation of energy principle. It simple states that during an interaction, energy can change from one form to another but the total amount of energy remains constant. That is, energy cannot be created or destroyed. The change in the energy input and the energy output, and the energy balance is expressed as
=Δ
The first law of thermodynamics is simply an expression of the conservation of energy principle, and it assets that energy is a thermodynamic property. The second law of thermodynamics asserts that energy has quality as well as quantity, and actual processes occur in the direction of decreasing quality of energy.
Substance consists of a large number of particles called molecules. The properties of the substance naturally depend on the behavior of these particles. For example, the pressure of a gas in a container is the result of momentum transfer between the molecules and the walls of the container. However, one does not need to know the behavior of the gas particles to determine the pressure in the container It would be sufficient to attach a pressure gage to the container. This macroscopic approach to the study of thermodynamics that does not require a knowledge of the behavior of individual particles is called classical thermodynamics. It provides a direct and easy way to the solution of engineering problems. A more elaborate approach, based on the average behavior of large groups of individual particles, is called statistical thermodynamic. This microscopic approach is rather involved and is used inn this text only in the supporting role.
Application Areas of Thermodynamics
All activities in nature involve some interaction between energy and matter; thus, it is hard to imagine an area that does not relate to thermodynamics in some manner. Therefore, developing a good understanding of basic principles of thermodynamics has long been essential part of engineering education.
Application of thermodynamics are right where one lives. Many ordinary household utensils and appliances are design, in whole or in part, by using the principles of thermodynamics. Some examples include the electric or gas range, the heating and air conditioning system. the refrigerator, the humidifier, the pressure cooker, the water heater, the shower, the iron and even the computer, and the TV. On larger scale, thermodynamics plays a major part in the design and analysis of automotive engines, rockets, jet engines, and conventional or nuclear power plants, solar collectors, and the design of vehicles from ordinary cars to air planes. The energy efficient home that you may be living in, for example, is designed on the basis of minimizing heat loss in winter and heat gain in summer. The size, location and the power input of the fan of your computer is also selected after an analysis that involves thermodynamics.