Adrian Bejan(Editor), Allan D. Kraus (Editor). Heat transfer Handbok (776115), страница 4
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— John Wiley & Sons / Page 42 / 2nd Proofs / Heat Transfer Handbook / Bejan[Last Page][42], (42)Lines: 2143 to 2162———313.90102pt PgVar———Normal PagePgEnds: TEX[42], (42)123456789101112131415161718192021222324252627282930313233343536373839404142434445CHAPTER 2Thermophysical Properties of Fluidsand Materials*R. T JACOBSENIdaho National Engineering and Environmental LaboratoryIdaho Falls, Idaho[First Page]E. W. LEMMONPhysical and Chemical Properties DivisionNational Institute of Standards and TechnologyBoulder, Colorado[43], (1)S. G. PENONCELLO and Z. SHANLines: 0 to 71———Center for Applied Thermodynamic StudiesCollege of EngineeringUniversity of IdahoMoscow, Idaho3.28333pt PgVarN.
T. WRIGHT———Normal PagePgEnds: TEXDepartment of Mechanical EngineeringUniversity of MarylandBaltimore, Maryland[43], (1)2.1 Introduction2.2 Thermophysical properties of fluids2.2.1 Thermodynamic propertiesEquation of stateCalculation of propertiesThermodynamic properties of mixtures2.2.2 Transport propertiesExtended corresponding statesDilute-gas contributionsDensity-dependent contributionsTransport properties of mixtures2.3 Thermophysical properties of solids2.3.1 Conservation of energy2.3.2 Behavior of thermophysical properties of solids*The material in this chapter is a contribution in part of the National Institute of Standards and Technology,not subject to copyright in the United States.
We gratefully thank Mark McLinden for permission to useportions of his work for the section on extended corresponding states, as well as the help and suggestionsof Daniel Friend and Joan Sauerwein, all of the National Institute of Standards and Technology.43BOOKCOMP, Inc. — John Wiley & Sons / Page 43 / 2nd Proofs / Heat Transfer Handbook / Bejan44123456789101112131415161718192021222324252627282930313233343536373839404142434445THERMOPHYSICAL PROPERTIES OF FLUIDS AND MATERIALS2.3.3 Property values of solid materials2.3.4 Measuring thermophysical properties of solidsThermal conductivitySpecific heatThermal diffusivityThermal expansionNomenclatureReferencesGraphs of thermophysical properties2.1INTRODUCTION[44], (2)The need for accurate thermophysical properties in the design and analysis of engineered systems is well established.
The industrial applications of various workingfluids and solids require a variety of property values with accuracies that range fromcrude estimates to precisions of 1 part in 10,000 for some sensitive applications. Itis particularly true that small errors in properties for custody transfer of fluids canresult in significant costs or benefits to those involved in commercial transactions. Itis the responsibility of the engineer to decide what level of accuracy is needed for aparticular application and to establish the uncertainty of the related design or analysisin light of the accuracy of the properties used.In addition to the individual properties for system design and analysis, there is aneed for combined heat transfer parameters and dimensionless groups that occur inequations for conduction, convection, and radiation.
These include:Biot numberFourier numberLewis numberPrandtl numberSchmidt numberBoussinesq numberGraetz numberNusselt numberRayleigh numberSherwood numberEckert numberGrashof numberPéclet numberReynolds numberOnly the Prandtl number is a fluid property; the others incorporate system characteristics such as velocity, length, or diameter. These groups are defined elsewhere in thisbook and are not discussed in this chapter.The term thermophysical properties is used here to refer to both thermodynamic(equilibrium) properties and transport properties. The thermodynamic properties define equilibrium states of the system and include such properties as temperature,pressure, density, internal energy, heat capacity, speed of sound, enthalpy, and entropy.
The transport properties are those such as thermal conductivity, viscosity, andthermal diffusivity which pertain to the transfer of momentum or energy within thesystem. In a practical sense, design and analysis of heat transfer systems requireinformation about both transport and thermodynamic properties. The thermodynamicproperties are generally well defined by measurement for most common fluids andBOOKCOMP, Inc. — John Wiley & Sons / Page 44 / 2nd Proofs / Heat Transfer Handbook / BejanLines: 71 to 108———0.15337pt PgVar———Long PagePgEnds: TEX[44], (2)INTRODUCTION12345678910111213141516171819202122232425262728293031323334353637383940414243444545mixtures and are usually of higher accuracy than the transport properties available forthe same fluids and mixtures. This is, in part, because the experimental methods formeasuring transport properties are generally less accurate than those for the thermodynamic properties, although the state of the art is improving for such measurements(see Wakeham et al., 1991).Current practice in the design and analysis of fluid systems requires the use ofcomputer programs in various forms for thermophysical properties.
Based on the experience of the authors in the development and evaluation of computer programs forengineered systems, we recommend the use of the most accurate computer databasesavailable to the engineer. Such sources of highly accurate properties are often referredto as standard reference quality sources, and many are the result of internationalagreements among qualified experts on the current best values of properties. A typicalaccurate equation of state is a polynomial with 15 to 35 terms, as described later.
Ifspecial applications require equations with fewer terms for rapidly estimating properties or for calculating abbreviated tables, these can be developed based on propertiescalculated by means of the best available models, and estimates of uncertainties inthe properties used in design can be determined by comparisons to values from thesource, the accuracies of which are generally well specified.We have assumed that the user of this book has access to a reasonably currentpersonal computer and to the World Wide Web. Because the National Institute ofStandards and Technology (NIST) databases generally incorporate the best availablefluid properties algorithms and equations, we rely heavily on those sources in therecommended values given in this chapter.
We provide summary tables of propertiesof common fluids and materials for estimating purposes and, at the end of the chapter,graphical comparisons of various properties of different fluids to assist in the selectionof materials for design. We have not, in general, attempted to repeat tabular valuesfor fluid properties that are readily available in other sources, including commonengineering textbooks and other handbooks, although some general tables of propertyvalues at common conditions are given for completeness.The values of the thermodynamic and transport properties for a large number offluids may be calculated using several comprehensive computer programs from NIST,including NIST Standard Reference Databases 10, 12, 14, and 23. A limited computerprogram is included in this book for use in calculating properties for design andanalysis of heat transfer systems using the most common fluids.
Some properties arealso available on the NIST Chemistry Webbook at http://webbook.nist.gov/chemistry.Although the NIST programs provide the most accurate values currently available, additional research, experimentation, and correlation activities worldwide willincrease the accuracy, the number of fluids, and the ranges of available states for thecovered fluids.
The full programs with source code and mixture capabilities are available from NIST at a nominal cost and are updated periodically. Details concerningthe current databases available from the Standard Reference Data Office of NIST arelocated at the Web address http://www.nist.gov/srd by searching for the key wordsNIST10, NIST12, NIST14, or NIST23.There are fewer sources of properties of solids for design than there are for fluids,and the data available have not yet been incorporated into evaluated wide-range computer models. The uncertainties associated with published values for many propertiesBOOKCOMP, Inc. — John Wiley & Sons / Page 45 / 2nd Proofs / Heat Transfer Handbook / Bejan[45], (3)Lines: 108 to 118———0.0pt PgVar———Long PagePgEnds: TEX[45], (3)46123456789101112131415161718192021222324252627282930313233343536373839404142434445THERMOPHYSICAL PROPERTIES OF FLUIDS AND MATERIALSof solids are generally larger than those for properties of fluids, in part because of impurities or compositional variations in experimental samples.
In this chapter we haveincluded selected properties of solids from reliable published sources.This chapter contains a minimum of theory and no details on the correlation andanalysis of thermophysical property data for determining the recommended values forboth fluids and solids. Literature references are given for the best available sourcesknown for the various properties. The references should be useful to the reader who isinterested in greater detail about the correlation methods and about the data on whichthe correlations and recommended values are based.2.2 THERMOPHYSICAL PROPERTIES OF FLUIDSThe thermodynamic and transport properties of fluids are discussed separately in thissection.
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