Although various aspects of what is now known as thermodynamics have been of interest since antiquity,
formal study began only in the early 19th century through consideration of the motive power of heat:
the capacity of hot bodies to produce work.
Today the scope is larger, dealing generally with energy and entyrop, and with relationships among the
properties of matter. Moreover, in the past 25 years engineering thermodynamics has undergone a revolution, both in terms of the presentation of fundamentals and in the manner that it is applied. In particular, the second law of thermodynamics has emerged as an effective tool for engineering analysis and design.
Fundamentals:
Classical thermodynamics is concerned primarily with the macrostructure of matter. It addresses the
gross characteristics of large aggregations of molecules and not the behavior of individual molecules.
The microstructure of matter is studied in kinetic theory and statistical mechanics (including quantum
thermodynamics). In this chapter, the classical approach to thermodynamics is featured.
Basic Concepts and Definitions Thermodynamics is both a branch of physics and an engineering science. The scientist is normally interested in gaining a fundamental understanding of the physical and chemical behavior of fixed, quiescent quantities of matter and uses the principles of thermodynamics to relate the properties of matter. Engineers are generally interested in studying systems and how they interact with their surroundings. To facilitate this, engineers have extended the subject of thermodynamics to the study of systems through
which matter flows. System In a thermodynamic analysis, the system is the subject of the investigation. Normally the system is a specified quantity of matter and/or a region that can be separated from everything else by a well-defined surface. The defining surface is known as the control surface or system boundary. The control surface may be movable or fixed. Everything external to the system is the surroundings.
A system of fixed mass is referred to as a control mass or as a closed system. When there is flow of mass through the control surface, the system is called a control volume, or open, system.
An isolated system is a closed system that does not interact in any way with its surroundings. State, Property The condition of a system at any instant of time is called its state. The state at a given instant of time is described by the properties of the system. A property is any quantity whose numerical value depends
on the state but not the history of the system. The value of a property is determined in principle by some type of physical operation or test. Extensive properties depend on the size or extent of the system. Volume, mass, energy, and entropy are examples of extensive properties. An extensive property is additive in the sense that its value for the whole system equals the sum of the values for its parts. Intensive properties are independent of the size or extent of the system. Pressure and temperature are examples of intensive properties.
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