INTRODUCTION OF THERMODYNAMICS :
The field of thermodynamics is concerned with the science of energy focusing on energy storage and energy conversion processes. We will study the effects on different substances, as we may expose a mass to heating/cooling or to volumetric compression/expansion.
During such processes we are transferring energy into or out of the mass, so it changes its conditions expressed by properties like temperature, pressure, and volume. We use several processes similar to this in our daily lives; we heat water to make coffee or tea or cool it in a refrigerator to make cold water or ice cubes in a freezer.
In nature, water evaporates from oceans and lakes and mixes with air where the wind can transport it, and later the water may drop out of the air as either rain (liquid water) or snow (solid water). As we study these processes in detail, we will focus on situations that are physically simple and yet typical of real-life situations in industry or nature.
By a combination of processes, we are able to illustrate more complex devices or complete systems—for instance, a simple steam power plant that is the basic system that generates the majority of our electric power. A power plant that produces electric power and hot water for district heating burns coal.
The coal is supplied by ship, and the district heating pipes are located in underground tunnels and thus are not visible. A more technical description and a better understanding are obtained from the simple schematic of the power plant, as shown in Fig. 1.2. This includes various outputs from the plant as electric power to the net, warm water for district heating, slag from burning coal, and other materials like ash and gypsum; the last output is a flow of exhaust gases out of the chimney.
Another set of processes forms a good description of a refrigerator that we use to cool food or apply it at very low temperatures to produce a flow of cold fluid for cryogenic surgery by freezing tissue for minimal bleeding. A simple schematic for such a system.
The same system can also function as an air conditioner with the dual purpose of cooling a building in summer and heating it in winter; in this last mode of use, it is also called a heat pump. For mobile applications, we can make simple models for gasoline and diesel engines typically used for ground transportation and gas turbines in jet engines used in aircraft, where low weight and volume are of prime concern.
These are just a few examples of familiar systems that the theory of thermodynamics allows us to analyze. Oncewe learn and understand the theory, we will be able to extend the analysis to other cases we may not be familiar with.
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