REFRIGERANTS HFC-134a - · PDF file1 Thermodynamic Properties of HFC-134a Refrigerant...

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Transcript of REFRIGERANTS HFC-134a - · PDF file1 Thermodynamic Properties of HFC-134a Refrigerant...

  • Technical Information

    T-134aSI

    f

    ThermodynamicPropertiesof

    HFC-134a(1,1,1,2-tetrafluoroethane)

    Du Pont Product Names:SUVA 134a RefrigerantFORMACEL Z-4 Blowing AgentDYMEL 134a Aerosol PropellantDYMEL 134a/P Aerosol Propellant

    (Pharmaceutical Grade)

    D U P O N T

    SUVA

    R E F R I G E R A N T S

  • 1

    Thermodynamic Properties of HFC-134a Refrigerant(1,1,1,2-tetrafluoroethane)

    SI Units

    New tables of the thermodynamic properties of HFC-134ahave been developed and are presented here. These tablesare based on experimental data from the database at theNational Institute of Standards and Technology (NIST).Equations have been developed, based on the ModifiedBenedict-Webb-Rubin (MBWR) equation of state, whichrepresent the data with accuracy and consistency through-out the entire range of temperature, pressure, and density.

    Physical PropertiesChemical Formula CH2FCF3Molecular Weight 102.03

    Boiling Point atOne Atmosphere 26.06C (14.9F)

    Critical Temperature 101.08C (213.9F)374.23 K (673.6R)

    Critical Pressure 4060.3 kPa (abs) (588.9 psia)

    Critical Density 515.3 kg/m3 (32.17 lb/ft3)

    Critical Volume 0.00194 m3/kg (0.031 ft3/lb)

    Units and Factorst = temperature in C

    T = temperature in K = C + 273.15P = pressure in kiloPascals absolute [kPa (abs)]vf = volume of saturated liquid in m

    3/kgvg = volume of saturated vapor in m

    3/kgV = volume of superheated vapor in m3/kgdf = 1/vf = density of saturated liquid in kg/m

    3

    dg = 1/vg = density of saturated vapor in kg/m3

    hf = enthalpy of saturated liquid in kJ/kghfg = enthalpy of vaporization in kJ/kghg = enthalpy of saturated vapor in kJ/kgH = enthalpy of superheated vapor in kJ/kgsf = entropy of saturated liquid in kJ/(kg) (K)sg = entropy of saturated vapor in kJ/(kg) (K)S = entropy of superheated vapor in kJ/(kg) (K)

    Cp = heat capacity at constant pressure in kJ/(kg) (C)Cv = heat capacity at constant volume in kJ/(kg) (C)vs = velocity of sound in m/sec

    The gas constant, R = 8.314 J/(mole) (K)for HFC-134a, R = 0.0815 kJ/kg K

    One atmosphere = 101.325 kPaReference point for enthalpy and entropy:

    hf = 200 kJ/kg at 0Csf = 1 kJ/kg K at 0C

    EquationsThe Modified Benedict-Webb-Rubin (MBWR) equation ofstate was used to calculate the tables of thermodynamicproperties. It was chosen as the preferred equation of statebecause it provided the most accurate fit of the thermo-dynamic data over the entire range of temperatures andpressures presented in these tables. The data fit and calcu-lation of constants for HFC-134a were performed forDu Pont at the National Institute of Standards and Tech-nology (NIST) under the supervision of Dr. Mark O.McLinden.

    The constants were calculated in SI units. For conversionof thermodynamic properties to Engineering (I/P) units,properties must be calculated in SI units and converted toI/P units. Conversion factors are provided for each propertyderived from the MBWR equation of state.

    1. Equation of State (MBWR)

    = an/Vn + exp (Vc2/V2) an/V2n17

    where the temperature dependence of the coefficients isgiven by:

    a1 = RT

    a2 = b1T + b2T0.5 + b3 + b4/T + b5/T

    2

    a3 = b6T + b7 + b8/T + b9/T2

    a4 = b10T + b11 + b12/T

    a5 = b13

    a6 = b14/T + b15/T2

    a7 = b16/T

    a8 = b17/T + b18/T2

    a9 = b19/T2

    a10 = b20/T2 + b21/T

    3

    a11 = b22/T2 + b23/T

    4

    a12 = b24/T2 + b25/T

    3

    a13 = b26/T2 + b27/T

    4

    a14 = b28/T2 + b29/T

    3

    a15 = b30/T2 + b31/T

    3 + b32/T4

    where T is in K = C + 273.15, V is in liters/mole(= m3/kg MW), Vc = 0.199334 liters/mole, P is in kPa,and R = 0.08314471 bar (absolute) liters/mole K.

    P100

    15

    n=10

    9

    n=1

  • 2

    MBWR coefficients for HFC-134a:b1 = 6.545 523 5227 E02b2 = 5.889 375 1817 E+00b3 = 1.376 178 8409 E+02b4 = 2.269 316 8845 E+04b5 = 2.926 261 3296 E+06b6 = 1.192 377 6190 E04b7 = 2.721 419 4543 E+00b8 = 1.629 525 3680 E+03b9 = 7.294 220 3182 E+05b10 = 1.172 451 9115 E04b11 = 8.686 451 0013 E01b12 = 3.066 016 8246 E+02b13 = 2.566 404 7742 E02b14 = 2.438 183 5971 E+00b15 = 3.160 316 3961 E+02b16 = 3.432 165 1521 E01b17 = 1.015 436 8796 E02b18 = 1.173 423 3787 E+00b19 = 2.730 176 6113 E02b20 = 6.633 850 2898 E+05b21 = 6.475 479 9101 E+07b22 = 3.729 521 9382 E+04b23 = 1.261 473 5899 E+09b24 = 6.474 220 0070 E+02b25 = 1.236 245 0399 E+05b26 = 1.569 919 6293 E+00b27 = 5.184 893 2204 E+05b28 = 8.139 632 1392 E02b29 = 3.032 516 8842 E+01b30 = 1.339 904 2297 E04b31 = 1.585 619 2849 E01b32 = 9.067 958 3743 E+00

    Ideal Gas Heat Capacity Equation (at constantpressure):

    Cp (J/mole K) = cp1 + cp2 T + cp3 T2

    cp1 = 1.94006 E+01 cp3 = 1.29665 E04cp2 = 2.58531 E01 R = 8.314471 J/mole K

    MW = 102.03

    Properties calculated in SI units from the equation andconstants listed above can be converted to I/P unitsusing the conversion factors shown below. Please notethat in converting enthalpy and entropy from SI to I/Punits, a change in reference states must be included(from H = 200 and S = 1 at 0C for SI units to H = 0and S = 0 at 40C for I/P units). In the conversionequation below, H (ref) and S (ref) are the saturatedliquid enthalpy and entropy at 40C. For HFC-134a,H (ref) = 148.4 kJ/kg and S (ref) = 0.7967 kJ/kg K.

    P (psia) = P (kPa) 0.14504T (F) = (T[C] 1.8) + 32D (lb/ft3) = D (kg/m3) 0.062428V (ft3/lb) = V (m3/kg) 16.018H (Btu/lb) = [H (kJ/kg) H (ref)] 0.43021S (Btu/lb R) = [S (kJ/kg K) S (ref)] 0.23901Cp (Btu/lb F) = Cp (kJ/kg K) 0.23901Cv (Btu/lb F) = Cv (kJ/kg K) 0.23901vs (ft/sec) = vs (m/sec) 3.2808

    2. Martin-Hou Equation of State (fit from MBWR data)

    As previously stated, the thermodynamic propertiespresented in these tables are based on the MBWRequation of state. Coefficients for the Martin-Houequation of state are presented below for the conve-nience of those who may have existing computerprograms based on this equation of state. While not asaccurate as the data from the MBWR equation of state,particularly in the superheated region, data calculatedusing these Martin-Hou coefficients should be suffi-cient for most engineering calculations.

    P = RT/(Vb) + (Ai + BiT + Ci exp (kT/Tc))/(Vb) i

    For SI units

    T and Tc are in K = C + 273.15, V is in m3/kg,

    and P is in kPa

    R = 0.0815 kJ/kg K

    b, Ai, Bi, Ci, k are constants:

    A2 = 8.909485 E02 A4 = 1.778071 E05

    B2 = 4.408654 E05 B4 = 4.016976 E08

    C2 = 2.074834 E+00 C4 = 2.977911 E04

    A3 = 1.016882 E03 A5 = 7.481440 E08

    B3 = 2.574527 E06 B5 = 1.670285 E10

    C3 = 2.142829 E02 C5 = 1.255922 E06

    b = 3.755677 E04 k = 4.599967

    O

    5

    i=2

  • 3

    3. Vapor Pressure

    log10 Psat = A + B/T + C log10 T + D T +E ([FT]/T) log10 (FT)

    For SI units

    T is in K = C + 273.15 and P is in kPa

    A, B, C, D, E, F are constants:

    A = 4.069889 E+01 D = 7.616005 E03

    B = 2.362540 E+03 E = 2.342564 E01

    C = 1.306883 E+01 F = 3.761111 E+02

    For I/P units

    T is in R = F + 459.67 and P is in psia

    A, B, C, D, E, F are constants:

    A = 4.325629 E+01 D = 4.231114 E03

    B = 4.293056 E+03 E = 2.342564 E01

    C = 1.306883 E+01 F = 6.770000 E+02

    4. Density of the Saturated Liquid

    df = Af + Bf (1Tr) (1/3) + Cf (1Tr)

    (2/3) + Df (1Tr)

    + Ef (1Tr) (4/3)

    For SI units

    Tr = T/Tc, both in K = C + 273.15 and df isin kg/m3

    Af, Bf, Cf, Df, Ef are constants:

    Af = 5.281464 E+02 Df = 9.491172 E+02

    Bf = 7.551834 E+02 Ef = 5.935660 E+02

    Cf = 1.028676 E+03

    For I/P units

    Tr = T/Tc, both in R = F + 459.67 and df is in lb/ft3

    Af, Bf, Cf, Df, Ef are constants:

    Af = 3.297110 E+01 Df = 5.925145 E+01

    Bf = 4.714456 E+01 Ef = 3.705512 E+01

    Cf = 6.421816 E+01

    For I/P units

    T and Tc are in R = F + 459.67, V is in ft3/lb,

    and P is in psia

    R = 0.1052 (psia)(ft3)/lb R

    b, Ai, Bi, Ci, k are constants:

    A2 = 3.315708 E+00 A4 = 1.697907 E01

    B2 = 9.115011 E04 B4 = 2.131040 E04

    C2 = 7.721597 E+01 C4 = 2.843653 E+00

    A3 = 6.061984 E01 A5 = 1.144381 E02

    B3 = 8.526469 E04 B5 = 1.419396 E05

    C3 = 1.277414 E+01 C5 = 1.921091 E01

    b = 6.016014 E03 k = 4.599967 E+00

    Ideal Gas Heat Capacity (at constant volume):

    Cv = a + bT + cT2 + dT3 + f/T2

    For SI units

    Cv = kJ/kg K

    T is in K = C + 273.15

    a, b, c, d, f are constants:

    a = 3.154856 E+00 d = 3.754497 E08

    b = 1.656054 E02 f = 3.023189 E+04

    c = 4.353378 E05

    For I/P units

    Cv = Btu/lb R

    T is in R = F + 459.67

    a, b, c, d, f are constants:

    a = 7.540287 E01 d = 1.538660 E09

    b = 2.198925 E03 f = 2.341093 E+04

    c = 3.211365 E06

    o

    o

    o

  • 4

    TABLE 1HFC134a Saturation PropertiesTemperature Table

    (continued)

    LIQUIDvf

    VAPORvg

    LIQUID1/vf

    VAPOR1/vg

    LIQUIDhf

    LATENThfg

    LIQUIDsf

    VAPORsg

    ENTROPYkJ/(kg)(K)

    VAPORhg

    PRESSUREkPa (abs)

    TEMP.C

    TEMP.C

    VOLUMEm3/kg

    DENSITYkg/m3

    ENTHALPYkJ/kg

    100 0.57 0.0006 25.0000 1580.5 0.040 77.3 259.9 337.2 0.4448 1.9460 10099 0.63 0.0006 22.7273 1577.8 0.044 78.4 259.4 337.8 0.4514 1.9407 9998 0.70 0.0006 20.4082 1575.0 0.049 79.6 258.8 338.4 0.4581 1.9356 9897 0.77 0.0006 18.5185 1572.3 0.054 80.7 258.2 339.0 0.4646 1.9306 9796 0.86 0.0006 16.9492 1569.5 0.059 81.9 257.7 339.6 0.4711 1.9257 96

    95 0.95 0.0006 15.3846 1566.8 0.065 83.0 257.1 340.1 0.4776 1.9209 9594 1.04 0.0006 13.8889 1564.1 0.072 84.2 256.6 340.7 0.4841 1.9161 9493 1.15 0.0006 12.6582 1561.3 0.079 85.3 256.0 341.3 0.