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Nu = 0.3 + [(0.62Re^1/2Pr^1/3)/(1 + (0.4/Pr)^2/3)^1/4][1 + (Re/28 200)^5/8]^4/5 for RePr>0.2 for average; T_fm • Correlations for spheres in cross‐flow for average; T_a; 3.5 < Re < 7.6 × 10⁴; 1 < (μa/μs) < 3.2 • Correlation for falling drop Nu = 2 + 0.6Re^1/2Pr^1/3[25(x/D)^−0.7] for average; T_a

Nomenclature

aacceleration, m/s2; thermal diffusivity, m2/s; absorptivityAcross‐sectional area, m2; surface area, m2BiBiot numbercmass fraction; constant in Tables 1.10 and 1.11cpspecific heat at constant pressure, kJ/kg Kcvspecific heat at constant volume, kJ/kg KCfaverage skin‐friction coefficientddiameter, m; depth normal to flow, mDdiameter, mEenergy, J or kJ; electric potential, V; constantĖenergy rate, W or kWFforce; drag force, NFoFourier numbergacceleration due to gravity (=9.81 m/s2)Gmass flow velocity, kg/s m2GzGraetz numberGrGrashof numberhspecific enthalpy, kJ/kg; heat transfer coefficient, W/m2 °C; head, mHenthalpy, kJ; overall heat transfer coefficient, W/m2 °C; head, mIelectric current, Akthermal conductivity, W/m°CKadiabatic modulusKEkinetic energy, J or kJLthickness, mmmass, kg; constantṁmass flow rate, kg/sMmolecular weight, kg/kmolnmole number, kmol; constant exponent in Tables 1.9 and 1.10NuNusselt numberPperimeter, m; pressure, Pa or kPaP*constant‐pressure gradient, Pa or kPaPePeclet numberPEpotential energy, J or kJPrPrandtl numberqheat rate per unit area, W/m2; flow rate per unit width or depthqhheat generation rate per unit volume, W/m3Qheat transfer, J or kJheat transfer rate, W or kWrreflectivity; radial coordinate; radial distance, mRgas constant, kJ/kg K; radius, muniversal gas constant, kJ/kg KRtthermal resistance, °C/WRaRayleigh numberReReynolds numbersspecific entropy, kJ/kg; streamline direction; distance, m; constant exponent in Tables 1.10 and 1.11Sentropy, kJ/KStStanton numberttime, s; transmissivityTtemperature, °C or KTsabsolute temperature of object surface, Kuspecific internal energy, kJ/kg; velocity in x direction, m/s; variable velocity, m/sUinternal energy, kJ; flow velocity, m/sxquality, kg/kg; cartesian coordinate; variableXlength for plate, mvspecific volume, m3/kg; velocity in y direction, m/smolal specific volume, kmol/kgVvolume, m3; velocity, m/sVxvelocity in x direction, m/sVrvelocity in radial direction, m/sVyvelocity in y direction, m/sVzvelocity in z direction, m/sVθtangential velocity, m/svolumetric flow rate, m3/swvelocity in z direction, m /symole fraction; cartesian coordinate, variable; coordinate normal to flowYcharacteristic dimension (length), mzcartesian coordinate, variableZcompressibility factor (Eq. (1.24)); elevation, m

Greek Letters

      Φtemperature difference, °C or Kθangleβvolumetric coefficient of thermal expansion, 1/Kδincrement; differenceμdynamic viscosity, kg/ms; root of the characteristic equationρdensity, kg/m3νkinematic viscosity, m2/s∆thickness of the stagnant film of fluid on the surface, m∆Ttemperature difference, K; overall temperature difference, °C or KσStefan–Boltzmann constant, W/m2 K4; electrical conductivity, 1/ohmεsurface emissivity, eddy viscosityτshear stress, N/m2∑summationπnumber (=3.14159)

Subscripts and Superscripts

aair; medium; surroundingsavaverageAfluid AbblackBfluid Bcconvection, criticalcdconductioncscontrol surfacecvcontrol volumeDdiametereelectrical; end; exitffluid; final; flow; force; frictionfmfilm conditionhheat generationHhigh temperaturehsheat storageicomponent; inputieinternal energylliquidLlow temperatureliqliquidmmidplane for plane wall; centerline for cylindermixmixturennth valuenbnonblackppreviousrradiationssurface; near surface; saturation; free stream; in direction parallel to streamlinettotal; thermaltottotalxx‐directionvvaporvapvaporyy‐directionzz‐directionsurroundings; ambient; environment; reference1first value; first state; initial1, 2, 3points

References

      1 1 Raznjevic, K. (1995). Handbook of Thermodynamic Tables, 2nd edition. New York: Begell House.

      2 2 Dincer, I. (2020). Thermodynamics: A Smart Approach. New York: Wiley.

      3 3 Moran, M.J. and Shapiro, H.N. (2007). Fundamentals of Engineering Thermodynamics, 6e. New York: Wiley.

      4 4 Szargut, J., Morris, D.R., and Steward, F.R. (1988). Exergy Analysis of Thermal, Chemical, and Metallurgical Processes. New York: Hemisphere.

      5 5 Dincer, I. (1997). Heat Transfer in Food Cooling Applications. Washington, DC: Taylor & Francis.

      6 6 Dincer, I. and Rosen, M.A. (2013). Energy: Energy, Environment and Sustainable Development. 2nd edition. New York: Elsevier.

      7 7 Dincer, I. (1998). Thermodynamics, exergy and environmental impact. Proceedings of the ISTP‐11, the 11th International Symposium on Transport Phenomena.

      8 8 Olson, R.M. and Wright, S.J. (1991). Essentials of Engineering Fluid Mechanics. New York: Harper & Row.

      9 9 Dincer, I. and Rosen, M.A. (1999). Energy, environment and sustainable development. Applied Energy 64: 427–440.

Study Questions/Problems

      Introduction, Thermodynamic Properties

      1 1.1 Why are SI units most widely used throughout the world?

      2 1.2 What is the difference between mass and weight?

      3 1.3 What is specific heat? Define two commonly used specific heats. Is specific heat a function of temperature?

      4 1.4 Explain the operating principle of thermocouples. List some typical applications for different types of thermocouples. What is the main advantage of thermocouples over other temperature sensors?

      5 1.5 Consider the flow of a refrigerant vapor through a compressor, which is operating at steady‐state conditions. Do mass flow rate and volume flow rate of the refrigerant across the compressor remain constant?

      6 1.6 Consider a refrigeration system consisting of a compressor, an evaporator, a condenser, and an expansion valve. Is it best to evaluate each component as a closed system or as a control volume, and as a steady‐flow system or unsteady‐flow system? Explain.

      7 1.7 What is the difference between an adiabatic system and an isolated system?

      8 1.8 Define intensive and extensive properties. Identify the following properties as intensive or extensive: mass, volume, density, specific volume, energy, specific enthalpy, total entropy, temperature, pressure.

      9 1.9 Define the terms system, process, and cycle.

      10 1.10 What is the difference between gauge pressure, absolute pressure, and vacuum? Define atmospheric pressure.

      11 1.11 What is

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