Bivens, D. B.

Geller, V. Z.

Yokozeki, A.

English

Purdue E-Pubs

Purdue UniversityPurdue e-PubsInternational Refrigeration and Air ConditioningConference School of Mechanical Engineering1996Thermodynamic Properties of R23/116Azeotropic MixtureD. B. BivensE. I. du Pont de Nemours & CompanyA. YokozekiE. I. du Pont de Nemours & CompanyV. Z. GellerThermophysics Research CenterFollow this and additional works at: http://docs.lib.purdue.edu/iraccThis document has been made available through Purdue e-Pubs, a service of the Purdue University Libraries. Please contact epubs@purdue.edu foradditional information.Complete proceedings may be acquired in print and on CD-ROM directly from the Ray W. Herrick Laboratories at https://engineering.purdue.edu/Herrick/Events/orderlit.htmlBivens, D. B.; Yokozeki, A.; and Geller, V. Z., "Thermodynamic Properties of R23/116 Azeotropic Mixture" (1996). InternationalRefrigeration and Air Conditioning Conference. Paper 356.http://docs.lib.purdue.edu/iracc/356THERMODYNAMIC PROPERTIES OF R23/116 AZEOTROPIC MIXTURE Donald B. Bivens and Akirnichi Y okozeki E. I. duPont de Nemours & Company Wilmington, DE 19898 Vladimir z. Geller Thermophysics Research Center San Francisco, CA 94116 ABSTRACT New measurements of critical parameters, saturated vapor pressure, saturated-liquid and saturated-vapor densities, and PVT-data for the superheated vapors of the R23/116 azeotropic mixture (46/54 mass percent) are presented. Saturated vapor pressure, saturated-liquid and saturated-vapor densities were measured over a temperature range from -40 to 10°C. PVT data for the superheated vapors were obtained on the isotherms and on the isochores by two independent experimental procedures over a temperature range from 10 to 60°C and a pressure range from 800 to 7350 kPa. The obtained results have been used for developing coefficients for a modified Martin-Hou equation of state and calculating the thermodynamic properties. NOMENCLATURE ideal gas heat capacity at P "" Const ideal gas heat capacity at V "" Const density critical density saturated liquid enthalpy vapor enthalpy pressure critical pressure PIPe, reduced pressure gas constant saturated liquid entropy vapor entropy temperature boiling point at atmospheric pressure critical temperature Tffc, reduced temperature specific volume molecular mass INTRODUCTION A family of new pure and mixed refrigerants is currently under consideration as long-term alternatives for low-temperature refrigeration. The azeotropic mixture of the refrigerants R23/116 (46/54 mass %) has been introduced as an alternative to R503. The R23/116 mixture has the proposed ASHRAE number R508B, 403 The successful application of this mixture as working fluid for low-temperature refrigerating systems requires reliable thermodynamic properties over a range of parameters including the saturated liquid and vapor and the single-phase vapor region. In this paper, we present new measurements of critical parameters, saturated vapor pressure, saturated-liquid and saturated-vapor densities, and PVT-data for the superheated vapors. A modified Martin-Hou equation of state and coefficients for calculating thermodynamic properties are also presented. EXPERlMENTAL PROCEDURE AND RESULTS Critical Parameters A special high pressure sapphire visual cell was used for measuring the critical parameters. The cell was installed inside the view temperature bath which provided precision temperature control (to ±0.002 oq. Near the critical point the experiments were performed with the temperature step of 0.005 °(. The critical point was determined by observing disappearance of the fluid meniscus. The uncertainties of critical temperature, pressure, and density measurements are estimated to be ±0.1 °(, ±5 kPa, and ±2 kg/m3, respectively. Saturated Properties Saturated vapor pressures were determined by direct pressure measurements using stainless steel cell and precision pressure transducer. The uncertainty of the saturated vapor pressure measurements is estimated to be ±0-1 %. Saturated-liquid and saturated-vapor densities were measured using cells constructed of stainless steel cylinder with volume of 180 cm3 and the sapphire visual tube. The sapphire tube was attached to the top of the stainless steel cylinder for measurements of saturated-liquid densities and to the bottom of this cylinder for measurements of saturated-vapor densities. In both cases, the visual tube allowed us to determine the level of phase equilibrium within the system and the volume of the system occupied by the certain phase. The uncertainties of the saturated-liquid and saturated-vapor density measurements are estimated to be ±0.2 %and ±0.5 %, respectively. Saturated properties of R508B are given in Table 1. PVT Measurements PVT-experiments for the superheated vapors were performed using two independent procedures: constant-volume method for measurements along the isochores and constant-temperature method for measurements along the isotherms. For both of them gravimetric determination of the amount of mixture under investigation was applied. The uncertainty of the temperature is ±0.02 oc, and for pressure it is less than ±0.05 %. The principal source of uncertainty is the cell volume which has an estimated statistical uncertainty of ±0.005 % and estimated systematic uncertainty of ±0.025 %. Overall, the uncertainty of the density values is estimated to be less than ±0.2 %. More detailed description of the experimental apparatus and procedure is given in our previous publication [1]. The results of PVT-measurements on the isotherms (I series) and on the isochores (ll series) are given in Tables 2 and 3, respectively. In the ll series, the measurements were done in the singe-phase region, and also in the two-phase region (vapor pressure data) for each isochore. Comparisons of the experimental PVT-data from two independent experimental series (Table 4) show that they are in good agreement. Two values of the saturated-vapor density were found by extrapolation of the experimental isochores to the saturation line. Comparisons of the saturated-vapor densities obtained by direct measurements and by extrapolation of the experimental isochores show that deviations are equal to 1.4 % and 1.1 %, respectively. 404 Table 1. Sahrrated properties of R508B T (DC) P (kPa) T (DC) dliq (kg/m3) T (DC) dvap (kg/m3) -41.08 816.9 -40.02 1316.1 -39.92 50.93 -40.00 846.0 -30.00 1250.3 -30.03 71.72 -31.14 1145.5 -25.02 1213.8 -25.01 85.30 -25.12 1386.3 -20.01 1175.5 -20.00 100.28 -20.01 1622.8 -14.99 1131.9 -15.03 119.32 -15.00 1871.1 -9.98 1084.4 -9.99 140.39 -9.97 2156.6 -4.99 1030.0 -5.00 167.04 -5.03 2465.7 0.03 969.1 0.01 199.40 0.01 2807.9 5.00 889.5 5.00 237.6 4.43 3146.8 9.99 781.2 10.02 304.3 8.07 3443.1 10.01 3619.6 12.20 3831.1 Table 2. PVT data of R508B (I series) T(DC) P (kPa) d (kg/m3) T (DC) P (kPa) d (kg/m3) 10.00 816.6 35.84 10.00 3320.8 235.17 20.00 850.9 35.84 20.00 3655.4 235.16 30.00 885.2 35.83 30.00 3977.0 235.15 40.00 925.2 35.83 40.00 4298.6 235.15 50.00 958.4 35.83 50.00 4611.5 235.14 60.00 987.0 35.82 60.00 4915.7 235.13 10.00 1268.7 58.80 30.00 4645.7 316.47 20.00 1329.1 58.80 40.00 5103.1 316.46 30.00 1382.6 58.79 50.00 5556.9 316.45 40.00 1440.3 58.79 60.00 6003.4 316.44 50.00 1502.0 58.79 30.00 5275.8 420.40 60.00 1561.0 58.78 40.00 5909.8 420.39 10.00 1961.9 100.49 50.00 6533.7 420.38 20.00 2076.3 100.49 60.00 7152.7 420.37 30.00 2186.1 100.48 30.00 5767.1 526.69 40.00 2291.8 100.48 40.00 6570.0 526.67 50.00 2401.0 100.48 50.00 7359.1 526.65 60.00 2513.2 100.47 10.00 2757.0 162.02 20.00 2962.2 164.01 30.00 3170.3 164.00 40.00 3372.5 164.00 50.00 3565.8 163.99 60.00 3759.1 163.99 405 Table 3. PVT measurements of R508B (II series) Pressure (kPa) T (OC) Isochore #1 Isochore#2 Saturated Pressure d == 219.82±0.05 kg/m3 d = 146.12±0.05. kg/m3 -16.00 1826.1 -13.09 1989.3 -10.77 2113.9 -6.14 2277.2 -2.55 2638.8 0.00 2386.0 0.32 2835.0 1.24 2904.2 3.16 3008.0 5.00 3060.8 10.00 3223.4 2563.6 20.00 3532.5 2745.1 30.00 3826.7 2914.2 40.00 4111.0 3085.2 50.00 4390.6 3245.5 Table 4. Comparisons of PVT data Pressure (kPa) T (OC) Isochore d = 219.82 kg/m.3 Isochore d = 146.12 kg/m.3 10 20 30 40 50 I series 3219 3525 3823 4115 4403 II series 3223 3533 3827 4111 4391 I series 2557 2740 2919 3090 3262 MODEL AND CORRELATIONS II series 2564 2745 2914 3085 3246 The data in this paper have been used to develop correlations for the present binary system. Often, in refrigerant applications, the Martin-Hou equation of state with auxiliary functions [2] is used for practical calculations. The following correlations based on the modified Martin-Hou model are given for R508B. 406 Equation of State (Martin-Hou EOS) P= RT + ± Ai+ BiT+ Ciexp(-kT I Tc) v- b i=2 (V- by (1) A2 = -9.859954·10-2 B2 = 1.329512·10-4 C2 = -2.750786·10° A3 = 1.943104·10-4 B3 = -3.673400·10-7 C3 = 8.136346·103 A 4 = -2.415544·10-7 B4 = 6.399736·10-1° C4 = -3.173366·10-5 As= 1.741779·10-10 Bs = -5.966795·10-13 c5 = 3.819294·10-8 R = 8.716059·10-2 b = 4.309291·10-4 k = 6.25; (Pin kPa, T inK, V in m3/kg, Pc = 3926 kPa, Tc = 287.14 K, de= 586.2 kg/m3, J.L = 95.393, and Tb = 184.88 K). Saturated Liquid Pressure <Bubble Point Pressure) 1 ln(P I Pc)=-(A+BX+ CX2 +DX3 +E X4 + F xs) Tr A= -1.41801 E = -0.06623 B = -6.57620 F = -2.91797 Saturated Vapor Pressure CDew Point Pressure) c = -0.27991 X= (1-T,)- Xo D = -1.45324 X0 = 0.215245 1 ln(P I Pc)=-(A+BX + CX2 +DX3 +EX4 + Fx5) T, A= -1.41842 E = -11.27539 B = -6.59163 F= -21.9375 Saturated Liquid Density A=l.O D = -9.550139 B = -0.1670326 E=4.713835 Ideal Gas Heat Capacit}L c = -0.612030 X= (1- Tr)- Xa c = 7.885847 x = (1- Tr)113 A= 1.5852536·10-1 B = 2.5441972·10-3 C = -2.028597·10-6 (Cp in kJ /kg·K, T inK, and ~=COP- 0. 087161). Saturated Liquid Enthalpy A = 141.066 B = -356.266 E = 2480.00 F = 2480.00 (HI in kJ /kg, Tin K, and Xa = 0.573528) c = -349.375 X=(l-Tr)l/3 -Xa 407 D =4.21582 X0 = 0.215245 D = 5.7703343·10-10 D=404.813 (2) (3) (4) (5) (6) Vapor Enthalpy 2 3 2 r ' Hv=AT+ BT + CT + DT +PV+l~+ A3 + A4 + As j' 2 3 4 · V-b 2(V-b)2 3(V-b/ 4(V-b)4 +e-kTITc(! + kTJ[....fL + C3 + C4 + Cs l +X Tc V-b 2(V-bi 3(V-b)3 4(V-b)4 A= 7.136477·10-2 B = 2.544197·10-3 C = -2.028597·10-6 D = 5.770334·10-10 (All other constants are same as in Eq. (1), Hv in kJ /kg, Tin K, P in kPa, V in m3/kg, and X= 186.059). Vapor Entropy Sv=Aln(T)+BT+CT2+DT3+Rln(V-b)-[___!!l_+ B3 z+ B4 3+ Bs 4] 2 3 V-b 2(V-b) 3(V-b) 4(V-b) k e-kT fTc~ C2 C3 C4 Cs ll + ~-+ + + +Y Tc V-b l(V-bi 3(V-b)3 4(V-b)4 ~ ~ A= 7.136477·10-2 B = 2.544197·10-3 C = -2.028597·10-6 D = 5.770334·10-10 (All other constants are same as in Eq. (1 ), Sv in kJ /kg·K, T inK, V in m3/kg, and Y = 0.77028). Saturated Liquid Entropy S -S_Hv-HI [- v T (Hz, Hv in kJ /kg, Sz, Svin kJ /kg·K, and T inK). CONCLUSION (7) (8) (9) New thermodynamic property measurements of R23/116 mixture (R508B) including critical parameters, saturated vapor pressure, saturated-liquid and saturated-vapor densities, and PVT-data for the superheated vapors are presented. These results have been used to develop coefficients for a modified Martin-Hou equation of state and thermodynamic property calculations. REFERENCES 1. Bivens, D. B., Yokozeki, A., Geller, V. z. Thermodynamic properties of R32/R125 mixture. In Proceedings of the 1995 International CFC and Halon Alternative Conference, Washington, DC, November 1995, pp. 107-116. 2. Martin, J. J. Thermodynamic and Transport Praperties of Gases, Liquids, and Solids. ASME, New York, 1959, pp. 110-125. 408 

Thermodynamic Properties of R23/116 Azeotropic Mixture

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Thermodynamic Properties of R23/116 Azeotropic Mixture

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