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0-1 PART 0 - PRELUDE: REVIEW OF “UNIFIED ENGINEERING THERMODYNAMICS” [IAW pp 2-22, 32-41 (see IAW for detailed SB&VW references); VN Chapter 1] 0.1 What it’s All About The focus of thermodynamics in 16.050 is on the production of work, often in the form of kinetic energy (for example in the exhaust of a jet engine) or shaft power, from different sources of heat. For the most part the heat will be the result of combustion processes, but this is not always the case. The course content can be viewed in terms of a “propulsion chain” as shown below, where we see a progression from an energy source to useful propulsive work (thrust power of a jet engine). In terms of the different blocks, the thermodynamics in Unified Engineering and in this course are mainly about how to progress from the second block to the third, but there is some examination of the processes represented by the other arrows as well. The course content, objectives, and lecture outline are described in detail in Handout #1. 0.2 Definitions and Fundamental Ideas of Thermodynamics As with all sciences, thermodynamics is concerned with the mathematical modeling of the real world. In order that the mathematical deductions are consistent, we need some precise definitions of the basic concepts. A continuum is a smoothed-out model of matter, neglecting the fact that real substances are composed of discrete molecules. Classical thermodynamics is concerned only with continua. If we wish to describe the properties of matter at a molecular level, we must use the techniques of statistical mechanics and kinetic theory . A closed system is a fixed quantity of matter around which we can draw a boundary. Everything outside the boundary is the surroundings . Matter cannot cross the boundary of a closed system and hence the principle of the conservation of mass is automatically satisfied whenever we employ a closed system analysis. The thermodynamic state of a system is defined by the value of certain properties of that system. For fluid systems, typical properties are pressure, volume and temperature. More complex systems may require the specification of more unusual properties. As an example, the state of an electric battery requires the specification of the amount of electric charge it contains. Properties may be extensive or intensive . Extensive properties are additive. Thus, if the system is divided into a number of sub-systems, the value of the property for the whole system is equal to the sum of the values for the parts. Volume is an extensive property. Intensive properties do not depend on the quantity of matter present. Temperature and pressure are intensive properties. Specific properties are extensive properties per unit mass and are denoted by lower case letters.
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This note was uploaded on 12/22/2011 for the course AERO 16.050 taught by Professor Zoltanspakovszky during the Fall '02 term at MIT.

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