Vapor-Phase PvTx Measurements of Binary Blends of cis-1,2,3,3,3

Article pubs.acs.org/jced

Cite This: J. Chem. Eng. Data XXXX, XXX, XXX−XXX

Vapor-Phase PvTx Measurements of Binary Blends of cis-1,2,3,3,3-Pentafluoroprop-1-ene + Isobutane and 3,3,3-Trifluoropropene + Isobutane Sebastiano Tomassetti,† Mariano Pierantozzi,‡ Giovanni Di Nicola,*,† Fabio Polonara,†,§ and J. Steven Brown∥

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†

Dipartimento di Ingegneria Industriale e Scienze Matematiche, Università Politecnica delle Marche, via Brecce Bianche 12, 60131 Ancona, Italy ‡ Scuola di Ateneo Architettura e Design, Università Degli Studi di Camerino, Ascoli Piceno, Italy § Consiglio Nazionale delle Ricerche (CNR): Construction Technologies Institute, Viale Lombardia 49, 20098 San Giuliano Milanese, MI, Italy ∥ Department of Mechanical Engineering, The Catholic University of America, Washington, D.C., United States ABSTRACT: Ninety-seven vapor-phase PvTx measurements are reported for six binary blends of cis-1,2,3,3,3-pentafluoroprop-1-ene (R1225ye(Z)) and isobutane (R600a), and sixty-six vapor-phase PvTx measurements are reported for four binary blends of 3,3,3-trifluoropropene (R1243zf) and R600a. The R1225ye(Z)/R600a data were recorded for six isochores of (0.0586, 0.0633, 0.0718, 0.0902, 0.1076, and 0.1218) m3·kg−1 for temperatures (303 < T < 383) K for six R600a mole fractions (0.504, 0.175, 0.797, 0.345, 0.477, 0.916). The R1243zf/R600a data were recorded for four isochores of (0.0944, 0.1614, 0.2306, and 0.6145) m3·kg−1 for temperatures (303 < T < 383) K for four R600a mole fractions (0.225, 0.434, 0.898, 0.282). The data were fitted using three equations of state: (1) ideal gas, (2) Peng−Robinson, and (3) truncated virial.

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INTRODUCTION Hydrofluorocarbons (HFCs), which are widely used in heating, ventilating, and air-conditioning applications, as well as many other applications, are potent greenhouse gases. While a number of commercially promising low global warming potential (GWP) working fluids are being developed to replace HFCs, as shown by, for example, McLinden et al.,1 only a limited number of single-component fluids possess the necessary combination of chemical, environmental, thermodynamic, and safety characteristics for many of these applications. Thus, it is becoming increasingly more important to blend single-component fluids in order to optimize the chemical, environmental, thermodynamic, and safety characteristics of the blended working fluid for a particular application. The authors have previously reported2−7 vapor-phase PvTx data for a number of low-GWP working fluids involving one of the following: carbon dioxide (R744), isobutane (R600a), methane (R50), nitrogen (R728), or propane (R290) blended with one of the following halogenated propene isomers: cis-1,2,3,3,3-pentafluoroprop-1-ene (R1225ye(Z)), 2,3,3,3tetrafluoroprop-1-ene (R1234yf), cis-1,3,3,3-tetrafluoroprop-1-ene (R1234ze(Z)), trans-1,3,3,3-tetrafluoroprop-1-ene (R1234ze(E)), or trans-1-chloro-3,3,3-trifluoroprop-1-ene (R1233zd(E)), where the two most recent of these papers have concentrated on R600a blended with one of the following: R1233zd(E), R1234yf, R1234ze(E), or R1234ze(Z). The present paper concentrates © XXXX American Chemical Society

once again on blends of R600a with halogenated propene isomers, extending the two previous studies by including R1225ye(Z) and 3,3,3-trifluoropropene (R1243zf). While these two working fluids are not currently widely being considered as commercially viable single-component working fluids, they have been, and are being, considered as potential blend components as evidenced by patent activity over the last 20 or so years. Moreover, as mentioned above, blends, such as the ones considered in this paper (R1225ye(Z)/R600a and R1243zf/R600a), can potentially offer benefits over single-component working fluids since their chemical, environmental, thermodynamic, and safety characteristics can be optimized for particular applications in ways that the single-component working fluid alone cannot be. Therefore, this paper continues the work of the authors by presenting vapor-phase PvTx data and fitting models for binary blends of R1225ye(Z)/R600a and R1243zf/R600a and thereby expands the thermodynamic property database of low-GWP working fluid blends.

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EXPERIMENTAL SECTION Materials. The samples of isobutane (R600a, CH(CH3)3, CAS number 75-28-5), cis-1,2,3,3,3-pentafluoroprop-1-ene Received: October 12, 2018 Accepted: January 17, 2019

A

DOI: 10.1021/acs.jced.8b00921 J. Chem. Eng. Data XXXX, XXX, XXX−XXX

Journal of Chemical & Engineering Data

Article

Table 1. R600a, R1225ye(Z), and R1243zf Sample Descriptions chemical name isobutane R1225ye(Z)a R1243zfb

source Matheson Gas Products Mexichem Fluor S.A. de C.V. Mexichem Fluor S.A. de C.V.

initial mole fraction purity 0.999 >0.97 0.995

purification method none several cycles of freezing, evacuation, melting, and ultrasonic agitation several cycles of freezing, evacuation, melting, and ultrasonic agitation

final mole fraction purity

analysis method

>0.98

GC

0.9975

GC

a

cis-1,2,3,3,3-Pentafluoroprop-1-ene. b3,3,3-Trifluoropropene.

Figure 1. Schematic view of the experimental setup.

A gravimetric method was used to prepare the blends. The first step involved subjecting the constant-volume test cell, tubing, and associated instrumentation to vacuum. Then, the desired amounts of the working fluids were transferred to the constant-volume cell. An analytical balance with an accuracy of ±0.3 mg was used to measure the mass of each blend component discharged from its container, after which the total mass of the blend was determined to be the difference between the discharged masses and the estimated masses of the working fluids remaining in the tubing, estimated to be between (0.01 and 0.06) g depending on the temperature, pressure, and molar mass of the working fluid. The resulting uncertainty at the 95% confidence level for the blend mass was estimated to be 0.9 mg.

(R1225ye(Z), CF3CFCHF, CAS number 5528-43-8), and 3,3,3-trifluoropropene (R1243zf, CF3CHCH2, CAS number 677-21-4) are described in Table 1. In order to remove noncondensable gases, the R1225ye(Z) and R1243zf samples were subjected to several cycles of freezing, evacuation, thawing, and ultrasonic stirring. Experimental Apparatus and Procedure. The experimental setup consisted of a constant-volume spherical test cell and two thermostatic baths covering the temperature range from (210 to 380) K and is illustrated in Figure 1. Since the experimental setup, test procedure, and experimental uncertainties are described in previous papers,2−9 only summary information is detailed in this section. B



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Table 2. Experimental Values of Pressure P, Specific Volume v, Temperature T, and Mole Fraction x in the Vapor Phase for R1225ye(Z)/R600a Blendsa T/K

P/kPa

v/m3·kg−1

T/K

308.15 313.15 318.15 323.15 328.15 333.15 338.15 343.15 348.15 353.15 358.15 363.15 368.15 373.15 378.15 383.15

xR600a = 0.175 316.0 321.9 327.8 333.7 339.5 346.4 351.2 357.0 362.8 368.6 374.3 380.1 385.9 391.6 397.3 403.1

0.0632 0.0632 0.0633 0.0633 0.0633 0.0633 0.0633 0.0633 0.0633 0.0634 0.0634 0.0634 0.0634 0.0634 0.0634 0.0634

303.15 308.15 313.15 318.15 323.15 328.15 333.15 338.15 343.15 348.15 353.15 358.15 363.15 368.15 373.15 378.15 383.15

0.0717 0.0717 0.0717 0.0717 0.0718 0.0718 0.0718 0.0718 0.0718 0.0718 0.0719 0.0719 0.0719 0.0719 0.0719 0.0719

308.15 313.15 318.15 323.15 328.15 333.15 338.15 343.15 348.15 353.15 358.15 363.15 368.15 373.15 378.15 383.15

0.0585 0.0585 0.0585 0.0585 0.0586 0.0586 0.0586 0.0586 0.0586 0.0586 0.0586 0.0586 0.0587 0.0587 0.0587 0.0587

308.15 313.15 318.15 323.15 328.15 333.15 338.15 343.15 348.15 353.15 358.15 363.15 368.15 373.15 378.15 383.15

308.15 313.15 318.15 323.15 328.15 333.15 338.15 343.15 348.15 353.15 358.15 363.15 368.15 373.15 378.15 383.15 308.15 313.15 318.15 323.15 328.15 333.15 338.15 343.15 348.15 353.15 358.15 363.15 368.15 373.15 378.15 383.15

xR600a = 0.345 309.8 315.5 321.3 327.0 332.9 338.6 344.2 349.8 355.4 361.0 366.6 372.2 377.8 383.4 389.0 394.6 xR600a = 0.477 410.6 418.8 426.9 434.9 442.8 450.8 458.7 466.6 474.5 482.3 490.2 497.9 505.7 513.5 521.3 529.0

P/kPa xR600a = 0.504 207.0 210.7 214.4 218.0 221.7 225.3 229.0 232.6 236.3 239.9 243.6 247.3 251.0 254.6 258.3 262.0 265.6 xR600a = 0.797 303.6 309.3 315.0 320.6 326.2 331.8 337.4 342.9 348.5 354.1 359.6 365.1 370.4 375.9 381.6 387.0 xR600a = 0.916 394.7 402.8 410.7 418.5 426.4 434.0 441.7 449.4 457.0 464.6 472.2 479.8 487.3 494.9 502.4 509.9

v/m3·kg−1 0.1216 0.1216 0.1216 0.1217 0.1217 0.1217 0.1217 0.1218 0.1218 0.1218 0.1218 0.1219 0.1219 0.1219 0.1220 0.1220 0.1220

Figure 2. Vapor-phase pressure P, specific volume v, temperature T, and mole fraction x data (Table 2) for R1225ye(Z)/R600a blends: +, xR600a = 0.175 and v = 0.0633 m3·kg−1; ▲, xR600a = 0.345 and v = 0.0718 m3·kg−1; ●, xR600a = 0.477 and v = 0.0586 m3·kg−1; Ο, xR600a = 0.504 and v = 0.1218 m3·kg−1; X, xR600a = 0.797 and v = 0.1076 m3·kg−1; Δ, xR600a = 0.916 and v = 0.0902 m3·kg−1.

Table 3. Experimental Values of Pressure P, Specific Volume v, Temperature T, and Mole Fraction x in the Vapor Phase for R1243zf/R600a Blendsa

0.1074 0.1074 0.1074 0.1074 0.1075 0.1075 0.1075 0.1075 0.1076 0.1076 0.1076 0.1076 0.1077 0.1077 0.1077 0.1077

T/K 308.15 313.15 318.15 323.15 328.15 333.15 338.15 343.15 348.15 353.15 358.15 363.15 368.15 373.15 378.15 383.15

0.0901 0.0901 0.0901 0.0901 0.0902 0.0902 0.0902 0.0902 0.0902 0.0903 0.0903 0.0903 0.0903 0.0903 0.0904 0.0904

303.15 308.15 313.15 318.15 323.15 328.15 333.15 338.15 343.15 348.15 353.15 358.15 363.15 368.15 373.15 378.15 383.15

a

Expanded uncertainties at the 95% confidence level are U(T) = 0.03 K, U(P) = 1 kPa, U(v) = 0.000165 m3•kg−1, and U(xR600a) = 0.002.

A 25 ohm resistance thermometer (Hart Scientific 5680) was used to make the temperature measurements, resulting in an expanded uncertainty at the 95% confidence level of 0.03 K. A pressure transducer (Ruska 7000) which has an uncertainty

P/kPa xR600a = 0.225 289.5 294.8 300.1 305.3 310.5 315.8 320.9 326.1 331.3 336.5 341.6 346.8 351.9 357.1 362.3 367.5 xR600a = 0.282 47.6 48.4 49.2 50.0 50.8 51.6 52.4 53.2 54.0 54.8 55.6 56.4 57.2 58.1 58.8 59.7 60.5

v/m3·kg−1

T/K

0.0942 0.0943 0.0943 0.0943 0.0943 0.0943 0.0944 0.0944 0.0944 0.0944 0.0944 0.0945 0.0945 0.0945 0.0945 0.0946

308.15 313.15 318.15 323.15 328.15 333.15 338.15 343.15 348.15 353.15 358.15 363.15 368.15 373.15 378.15 383.15

0.6134 0.6136 0.6137 0.6139 0.6140 0.6141 0.6143 0.6144 0.6145 0.6147 0.6148 0.6149 0.6151 0.6152 0.6153 0.6155 0.6156

303.15 308.15 313.15 318.15 323.15 328.15 333.15 338.15 343.15 348.15 353.15 358.15 363.15 368.15 373.15 378.15 383.15

P/kPa xR600a = 0.434 192.7 196.0 199.4 202.4 205.9 209.4 212.0 215.5 218.9 222.4 225.0 228.5 231.9 235.2 236.9 240.1 xR600a = 0.898 169.8 172.8 175.8 178.7 181.7 184.7 187.6 190.4 193.4 196.3 199.4 202.3 205.3 208.1 211.1 213.4 217.1

v/m3·kg−1 0.1611 0.1611 0.1611 0.1612 0.1612 0.1613 0.1613 0.1613 0.1614 0.1614 0.1614 0.1615 0.1615 0.1615 0.1616 0.1616 0.2302 0.2303 0.2303 0.2304 0.2304 0.2305 0.2305 0.2306 0.2306 0.2307 0.2307 0.2308 0.2308 0.2309 0.2309 0.2310 0.2310

a

Expanded uncertainties at the 95% confidence level are U(T) = 0.03 K, U(P) = 1 kPa, U(v) = 0.00256 m3·kg−1, and U(xR600a) = 0.011. C



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Figure 4. Biases (ΔP/P = (Pcalc − Pexp)/Pexp) between the Peng− Robinson15 equation of state (Pcalc) for R1225ye(Z)/R600a coupled with a van der Waals one-fluid linear mixing model16 with binary interaction parameters optimized (Table 5) for each isochore (model PR2) and the data of Table 2 (Pexp): +, xR600a = 0.175 and v = 0.0633 m3·kg−1; ▲, xR600a = 0.345 and v = 0.0718 m3·kg−1; ●, xR600a = 0.477 and v = 0.0586 m3·kg−1; Ο, xR600a = 0.504 and v = 0.1218 m3·kg−1; X, xR600a = 0.797 and v = 0.1076 m3·kg−1; Δ, xR600a = 0.916 and v = 0.0902 m3·kg−1.

Figure 3. Vapor-phase pressure P, specific volume v, temperature T, and mole fraction x data (Table 3) for R1243zf/R600a blends: Ο, xR600a = 0.225 and v = 0.0944 m3·kg−1; +, xR600a = 0.282 and v = 0.6145 m3·kg−1; ●, xR600a = 0.434 and v = 0.1614 m3·kg−1; ▲, xR600a = 0.898 and v = 0.2306 m3·kg−1.

Table 4. Coefficients for Equation 4 R1225ye(Z)/R600a R1243zf/R600a

D1

D2

D3

0.2628 0.0419

0.1926 0.3886

0.4980 0.5670

of ±0.003% of its full scale (kPa) was used to make the pressure measurements. Considering the uncertainty of the transducer and the influence of temperature fluctuations due to bath instability, the expanded uncertainty in pressure measurement at the 95% confidence level was found to be 1 kPa. The volume of the constant-volume test cell was estimated to be 273.5 cm3 at 298 K, resulting in an expanded uncertainty at the 95% confidence level of 0.3 cm3. A correction for thermal expansion and pressure distortion of the isochoric cell was considered, as reported elsewhere.8 Consequently, the specific volume of the sample slightly varies during the test procedure. As explained in previous papers,6,7 the uncertainty in the specific volume depends on the uncertainties in the volume estimation and the mass measurement. Meanwhile, the uncertainty in the molar fraction depends on the mass of the blend sample charged into the isochoric sphere, on the specific volume of the blend sample, and on the molar fraction itself. Considering the equations based on the law of error propagation proposed elsewhere,6,7 the uncertainties in the mass measurements and the volume estimations resulted in specific volume-expanded uncertainties at the 95% confidence level for the R1225ye(Z)/ R600a blends ranging from (0.068 to 0.165) dm3·kg−1 and for the R124zf/R600a blends ranging from (0.119 to 2.562) dm3·kg−1. It is worth noting that the larger uncertainties in the specific

Figure 5. Biases (ΔP/P = (Pcalc − Pexp)/Pexp) between the Peng− Robinson15 equation of state (Pcalc) for R1243zf/R600a coupled with a van der Waals one-fluid linear mixing model15 with binary interaction parameters optimized (Table 5) for each isochore (model PR2) and the data of Table 2 (Pexp): Ο, xR600a = 0.225 and v = 0.0944 m3·kg−1; +, xR600a = 0.282 and v = 0.6145 m3·kg−1; ●, xR600a = 0.434 and v = 0.1614 m3·kg−1; ▲, xR600a = 0.898 and v = 0.2306 m3·kg−1.

volume measurement for the R1243zf/R600a blends is due to the lower amounts of sample used in the tests.

Table 5. Binary Interaction Parameters (k12) for the One-Fluid Mixing Model Coupled with the Peng−Robinson Equation of State R1225ye(Z)/R600a −1

R1243zf/R600a −1

xR600a

v/m ·kg

k12 PR1

k12 PR2

xR600a

v/m ·kg

k12 PR1

k12 PR2

0.175 0.345 0.477 0.504 0.797 0.916

0.0632 0.0717 0.0585 0.1216 0.1074 0.0901

0.0039 0.0039 0.0039 0.0039 0.0039 0.0039

0.0078 −0.1763 0.1148 −0.2234 0.2172 −0.3486

0.225 0.282 0.434 0.898

0.0942 0.6134 0.1611 0.2302

0.1232 0.1232 0.1232 0.1232

−0.2448 0.1752 0.2127 0.5091

3

D

3



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Table 6. Coefficients for Bblend [Equation 3] and for Cblend [Equation 4] B1

B2

B3

B4

B5

R1225ye(Z)/R600a R1243zf/R600a

0.78614 −1.2596 C1

−12.372 −1221.3 C2

−8.0381 541.76 C3

12.419 −690.12 C4

−9.3286 160.47 C5

R1225ye(Z)/R600a R1243zf/R600a

−13.354 −6.9015

−4840.1 2717.5

63.906 −6091.1

−97.185 7812.3

125.41 −1600.7

Figure 6. (a) Constant Bblend [eq 3] for R1225ye(Z)/R600a blends as a function of mole fraction x of R600a and temperature T. (b) Constant Cblend [eq 4] for R1225ye(Z)/R600a blends as a function of mole fraction x of R600a and temperature T. (c) Constant Bblend [eq 3] for R1243zf/R600a blends as a function of mole fraction x of R600a and temperature T. (d) Constant Cblend [eq 4] for R1243zf/R600a blends as a function of mole fraction x of R600a and temperature T. Each symbol represents one of the 17 measured isotherms ranging from (303.2 to 383.2) K.

for the single-component (unblended) working fluids R1225ye(Z) and R1243zf.

The uncertainties in the blend masses, specific volumes, and molar fractions resulted in expanded uncertainties in the isobutane molar fractions at the 95% confidence level for the R1225ye(Z)/R600a blends ranging from (0.001 to 0.002) and for the R1243zf/R600a blends ranging from (0.002 to 0.011).6,7 The test procedure consisted of establishing the bath temperature at the desired value, allowing the bath and sample temperatures to equilibrate, and allowing the two temperatures to stabilize for a minimum of 20 min before a measurement was taken. The test procedure was then repeated until measurements had been taken for each desired temperature value. Note that previous papers10−13 report measurements made with this experimental setup following the test procedure described above of vapor pressures, liquid densities, and vapor-phase PvTx

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RESULTS AND DISCUSSION Experimental Data. Table 2 and Figure 2 report ninetyseven vapor-phase PvTx measurements for binary blends of R1225ye(Z)/R600a, and Table 3 and Figure 3 report sixty-six vapor-phase PvTx measurements for binary blends of R1243zf/ R600a. The R1225ye(Z)/R600a data were recorded for six isochores of (0.0586, 0.0633, 0.0718, 0.0902, 0.1076, and 0.1218) m3·kg−1 for temperatures (303 < T < 383) K for six R600a mole fractions (0.504, 0.175, 0.797, 0.345, 0.477, 0.916). The R1243zf/R600a blends were recorded for four isochores (0.0944, 0.1614, 0.2306, and 0.6145) m3·kg−1 for

E



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Ideal Gas Model. The ideal gas law was used to model the behaviors of the blends, where the mean bias is given by ij n ΔPi n Pcalc,i − Pexp,i y zzand the mean absolute bias is jj∑i = 1 P = ∑i = 1 P z i exp,i k { ij n ΔPi Pcalc,i − Pexp,i y n zz. The mean bias and given by jj∑i = 1 P = ∑i = 1 z Pexp,i i k { the mean absolute bias between the ideal gas law (Pcalc) and the experimental data for the R1225ye(Z)/R600a blends (Table 2) are 6.97% and 6.97%, respectively. The same biases for the R1243zf blends (Table 3) are 3.50% and 3.50%, respectively. The ideal gas model is included to illustrate that such a simple model is unable to adequately capture the behaviors of the blends, and thus more complex models (see below) are required. Peng−Robinson Equation of State. A Peng−Robinson (PR) EoS15 coupled with a one-fluid linear van der Waals mixing model16 was used to fit the measured data. Two models (PR1 and PR2) were developed. While the two models differ in the manner by which the binary interaction parameters (k12) were established, in each case they were determined through minimization of mean absolute bias. For the first model (PR1), k12 is based on all of the measured data, and for the second model (PR2), the k12 values were determined for each isochore based only on the data from the relevant isochore. Table 5 provides k12 values for PR1 and PR2 for both blends. Figure 4 shows biases for PR2 for the R1225ye(Z)/R600a blends, with resulting mean and absolute mean biases of −0.016% and 0.080%, respectively. Figure 5 shows similar data for the R1243zf/R600a blends, with resulting mean and absolute mean biases of −0.010% and 0.099%, respectively. Virial Equation of State. The data of Tables 2 and 3 were fitted to a truncated virial EoS

Figure 7. Biases (ΔP/P = (Pcalc − Pexp)/Pexp) between the firial equation of state (Pcalc) of eq 2 and the data of Table 2 (Pexp) for R1225ye(Z)/R600a blends: +, xR600a = 0.175 and v = 0.0633 m3·kg−1; ▲, xR600a = 0.345 and v = 0.0718 m3·kg−1; ●, xR600a = 0.477 and v = 0.0586 m3·kg−1; Ο, xR600a = 0.504 and v = 0.1218 m3·kg−1; X, xR600a = 0.797 and v = 0.1076 m3·kg−1; Δ, xR600a = 0.916 and v = 0.0902 m3·kg−1.

P=

B C yz RT ij jj1 + blend + blend z 2 z v k v v {

−1

(2) −1

where P is in kPa; R is in kJ·kmol K ; v and Bblend are in m3· kmol−1; and Cblend is in m6·kmol−2. As in our previous work,5−7 the constants Bblend and Cblend were fitted to the equations Figure 8. Biases (ΔP/P = (Pcalc − Pexp)/Pexp) between the virial equation of state (Pcalc) of eq 2 and the data of Table 3 (Pexp) for R1243zf/R600a blends: Ο, xR600a = 0.225 and v = 0.0944 m3·kg−1; +, xR600a = 0.282 and v = 0.6145 m3·kg−1; ●, xR600a = 0.434 and v = 0.1614 m3·kg−1; ▲, xR600a = 0.898 and v = 0.2306 m3·kg−1.

B2 2 + B3x R600a + B4 x R600a + B5 T

(3)

C blend = C1 ln T +

C2 2 + C3x R600a + C4x R600a + C5 T

(4)

where T is in K. The absolute mean biases for each blend pair were minimized in order to establish the B and C coefficients (Table 6). Figures 6a and 6b provide the coefficients for blends of R1225ye(Z)/R600a, and Figures 6c and 6d provide the coefficients for blends of R1243zf/R600a. Figures 7 and 8 provide biases between the virial EoS and experimental data for R1225ye(Z)/R600a blends and R1243zf/R600a blends, respectively. The mean bias and absolute mean bias for the R1225ye(Z)/R600a blends are −0.007% and 0.031%, respectively. The same biases for the R1243zf/R600a blends are −0.020% and 0.071%, respectively. Summary of Model Results. Table 7 provides percentages of the data falling within the indicated bounds for the various models for the R1225ye(Z)/R600a and R1243zf/ R600a blends. The models PR2 and virial perform the best. Specifically, 97% of the data for both blends fall within ±0.5% of the measured values for the PR2 model, and 94.8% of the data for both blends fall within ±0.25% of the measured values

temperatures (303 < T < 383) K for four R600a mole fractions (0.225, 0.434, 0.898, 0.282). Summary of Thermodynamic Behavior of Blends. The vapor-phase pressures of the blends vary as a function of the isobutane mole fraction from values of the lower-pressure components (R1225ye(Z) and R1234zf) to the values of the higher-pressure component (isobutane). As in our previous paper,7 the following equation was used to represent the nonlinear relationship Pblend − PR1225ye(Z)orR1243zf PR600a − PR1225ye(Z)orR1243zf 3 2 = D1x R600a + D2x R600a + D3x R600a

B blend = B1 ln T +

(1)

where the coefficients are provided in Table 4. Note: the equation of state (EoS) for R1225ye(Z) is a Martin-Hou EoS11 and for R1243zf is a Helmoltz free energy EoS.14 F



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Table 7. Percentage of Measured Data Falling Within Specified Bounds for Binary Blends of R1225ye(Z)/R600a and R1243zf/ R600a for Several Equations of Statea R1225ye(Z)/R600a

R1243zf/R600a

bounds

ideal gas

PR1

PR2

virial

ideal gas

PR1

PR2

Virial

±0.025% ±0.05% ±0.25% ±0.50% ±1.00% ±1.50% ±2.50%

0.0 0.0 0.0 0.0 0.0 0.0 0.0

4.1 8.2 15.5 43.3 100.0 100.0 100.0

20.6 45.4 94.8 100.0 100.0 100.0 100.0

52.6 85.6 99.0 100.0 100.0 100.0 100.0

0.0 0.0 0.0 0.0 0.0 0.0 0.0

6.1 9.1 39.4 72.7 100.0 100.0 100.0

24.2 50.0 89.4 97.0 100.0 100.0 100.0

24.2 50.0 95.5 100.0 100.0 100.0 100.0

a PR1 is the Peng−Robinson EoS with a mean interaction parameter for R1225ye(Z)/R600a of 0.0039 and for R1243zf/R600a of 0.1232. PR2 is the Peng−Robinson EoS with binary interaction parameters optimized for each isochore, and virial is the truncated virial EoS described in eq 2.

ORCID

Table 8. Absolute Mean Bias Between Models and Measured Data for Blends of R1225ye(Z)/R600a and R1243zf/R600aa R1225ye(Z)/R600a ideal gas

PR1

PR2

6.97

0.456

0.080

Giovanni Di Nicola: 0000-0001-9582-8764 J. Steven Brown: 0000-0003-4914-7778 Funding

R1243zf/R600a virial

ideal gas

PR1

PR2

virial

0.031

3.50

0.368

0.099

0.071

This work was supported by MIUR of Italy within the framework of PRIN2015 project “Clean Heating and Cooling Technologies for an Energy Efficient Smart Grid”. Notes

a

PR1 is the Peng−Robinson EoS with a mean interaction parameter for R1225ye(Z)/R600a of 0.0039 and for R1243zf/R600a of 0.1232. PR2 is the Peng−Robinson EoS with binary interaction parameters optimized for each isochore, and virial is the truncated virial EoS described in eq 2.

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS The authors thank Mexichem Fluor S.A. de C.V. for providing the R1225ye(Z) and R1243zf samples.

for the virial model. If the bounds are loosened to ±1.0% of the measured data, then 100% of the data for both blends fall within these bounds for the PR1, PR2, and virial models. It is to be noted that this bound is adequate for many engineering calculations. On the other hand, the ideal gas model yields predictions that are inadequate even for engineering calculations. Table 8 shows the mean absolute biases for the various models for the blends. The mean absolute biases for the R1225ye(Z)/ R600a blends are 0.080% and 0.031% for the PR2 and virial models, respectively, whereas the mean absolute biases for the R1243zf/R600a blends are 0.099% and 0.071% for the PR2 and virial models, respectively.

(1) McLinden, M. O.; Brown, J. S.; Brignoli, R.; Kazakov, A. F.; Domanski, P. A. Limited options for low-global-warming-potential refrigerants. Nat. Commun. 2017, 8, 14476. (2) Di Nicola, G.; Di Nicola, C.; Arteconi, A.; Stryjek, R. PVTx measurements of the carbon dioxide + 2,3,3,3-Tetrafluoroprop-1-ene binary system. J. Chem. Eng. Data 2012, 57, 450−455. (3) Di Nicola, G.; Passerini, G.; Polonara, F.; Stryjek, R. PVTx measurements of the carbon dioxide + trans-1,3,3,3-Tetrafluoroprop1-ene binary system. Fluid Phase Equilib. 2013, 360, 124−128. (4) Brown, J. S.; Corvaro, F.; Di Nicola, G.; Giuliani, G.; Pacetti, M. PVT measurements of trans-1,3,3,3-tetrafluoroprop-1-ene + methane and trans-1,3,3,3-tetrafluoroprop-1-ene + nitrogen binary pairs. J. Chem. Eng. Data 2014, 59, 3798−3804. (5) Brown, J. S.; Coccia, G.; Di Nicola, G.; Pierantozzi, M.; Polonara, F. Vapor phase PvTx measurements of binary blends of 2,3,3,3-tetrafluoroprop-1-ene + propane and cis-pentafluoroprop-1ene + propane. J. Chem. Eng. Data 2016, 61, 3346−3354. (6) Brown, J. S.; Coccia, G.; Tomassetti, S.; Pierantozzi, M.; Di Nicola, G. Vapor phase PvTx measurements of binary blends of 2,3,3,3-tetrafluoroprop-1-ene + isobutane and trans-1,3,3,3-tetrafluoroprop-1-ene + isobutane. J. Chem. Eng. Data 2017, 62, 3577−3584. (7) Brown, J. S.; Coccia, G.; Tomassetti, S.; Pierantozzi, M.; Di Nicola, G. Vapor Phase PvTx measurements of binary blends of trans1-chloro-3,3,3-trifluoroprop-1-ene + isobutane and cis-1,3,3,3-tetrafluoroprop-1-ene + isobutane. J. Chem. Eng. Data 2018, 63, 169−177. (8) Giuliani, G.; Kumar, S.; Polonara, F. A constant volume apparatus for vapour pressure and gas phase P-v-T measurements: Validation with data for R22 and R134a. Fluid Phase Equilib. 1995, 109, 265−279. (9) Di Nicola, G.; Polonara; Ricci, R.; Stryjek, R. PVTx measurements for the R116 + CO2 and R41 + CO2 systems. New isochoric apparatus. J. Chem. Eng. Data 2005, 50, 312−318. (10) Fedele, L.; Di Nicola, G.; Brown, J. S.; Colla, L.; Bobbo, S. Saturated pressure measurements of cis-1,2,3,3,3-pentafluoroprop-1ene (R1225ye(Z)). Int. J. Refrig. 2016, 69, 243−250.

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CONCLUSIONS This paper presents vapor-phase PvTx measurements and fitting models for two low-GWP working fluid blends. Each blend contains isobutane and a low-GWP fluorinated propene isomer, either cis-1,2,3,3,3-pentafluoroprop-1-ene (R1225ye(Z)) or 3,3,3-trifluoropropene (R1243zf). The presented results expand the thermodynamic property database of low-GWP working fluid blends by presenting measured data and fitting models for several R600a/R1225ye(Z) and R600a/R1243zf blends. Even if R1225ye(Z) and R1243zf are not currently widely being considered as commercially viable single-component working fluids, the two blends studied in this paper can potentially offer benefits over single-component working fluids since their chemical, environmental, thermodynamic, and safety characteristics can be optimized for particular applications in ways that the single-component working fluid alone cannot be.

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REFERENCES

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(11) Brown, J. S.; Fedele, L.; Di Nicola, G.; Bobbo, S.; Coccia, G. Compressed liquid density and vapor phase PvT measurements of cis1,2,3,3,3-pentafluoroprop-1-ene (R1225ye(Z)). J. Chem. Eng. Data 2015, 60, 3333−3340. (12) Brown, J. S.; Di Nicola, G.; Fedele, L.; Bobbo, S.; Zilio, C. Saturated pressure measurements of 3,3,3-trifluoroprop-1-ene (R1243zf) for reduced temperatures ranging from 0.62 to 0.98. Fluid Phase Equilib. 2013, 351, 48−52. (13) Di Nicola, G.; Brown, J. S.; Fedele, L.; Securo, M.; Bobbo, S.; Zilio, C. Subcooled liquid density measurements and PvT measurements in the vapor phase for 3,3,3-trifluoroprop-1-ene (R1243zf). Int. J. Refrig. 2013, 36, 2209−2215. (14) Lemmon, E. W.; Huber, M. L.; McLinden, M. O. NIST Standard Reference Database 23, Reference Fluid Thermodynamic and Transport Properties (REFPROP), version 10.0; National Institute of Standards and Technology: Gaithersburg, MD, 2018 (R1243zf.fld file updated October 22, 2017). (15) Peng, D.; Robinson, D. B. A new two-constant equation of state. Ind. Eng. Chem. Fundam. 1976, 15, 59−64. (16) Poling, B. E.; Prausnitz, J. M.; O’Connell, J. P. The Properties of Gases and Liquids, 5th ed.; McGraw-Hill: New York, 2004; p 6.29.

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Vapor-Phase PvTx Measurements of Binary Blends of cis-1,2,3,3,3

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