Thermodynamics

36 | Thermodynamicsplace of medical school training. Neither will engineering software packagesreplace the traditional engineering education. They will simply cause a shiftin emphasis in the courses from mathematics to physics. That is, more timewill be spent in the classroom discussing the physical aspects of the problemsin greater detail, and less time on the mechanics of solution procedures.All these marvelous and powerful tools available today put an extra burdenon today’s engineers. They must still have a thorough understanding ofthe fundamentals, develop a “feel” of the physical phenomena, be able toput the data into proper perspective, and make sound engineering judgments,just like their predecessors. However, they must do it much better,and much faster, using more realistic models because of the powerful toolsavailable today. The engineers in the past had to rely on hand calculations,slide rules, and later hand calculators and computers. Today they rely onsoftware packages. The easy access to such power and the possibility of asimple misunderstanding or misinterpretation causing great damage make itmore important today than ever to have solid training in the fundamentals ofengineering. In this text we make an extra effort to put the emphasis ondeveloping an intuitive and physical understanding of natural phenomenainstead of on the mathematical details of solution procedures.Engineering Equation Solver (EES)EES is a program that solves systems of linear or nonlinear algebraic or differentialequations numerically. It has a large library of built-in thermodynamicproperty functions as well as mathematical functions, and allows theuser to supply additional property data. Unlike some software packages,EES does not solve engineering problems; it only solves the equations suppliedby the user. Therefore, the user must understand the problem and formulateit by applying any relevant physical laws and relations. EES savesthe user considerable time and effort by simply solving the resulting mathematicalequations. This makes it possible to attempt significant engineeringproblems not suitable for hand calculations, and to conduct parametric studiesquickly and conveniently. EES is a very powerful yet intuitive programthat is very easy to use, as shown in Examples 1–11 and 1–12. The use andcapabilities of EES are explained in Appendix 3 on the enclosed DVD.EXAMPLE 1–11Solving a System of Equations with EESThe difference of two numbers is 4, and the sum of the squares of these twonumbers is equal to the sum of the numbers plus 20. Determine these twonumbers.Solution Relations are given for the difference and the sum of the squaresof two numbers. They are to be determined.Analysis We start the EES program by double-clicking on its icon, open anew file, and type the following on the blank screen that appears:xy 4x^2y^2 xy20