Measurement of Vapor–Liquid Equilibria for the Binary Mixture of

Jun 24, 2014 - Young Lae Kim,* Sung Jin Park, HoYun Choi, Jong-min Baek, Han Dock ... Robinson equation of state using the Wong−Sandler mixing rules...
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Measurement of Vapor−Liquid Equilibria for the Binary Mixture of Octafluoropropane and Hexafluoropropylene Oxide Containing Octafluorocyclobutane Young Lae Kim,* Sung Jin Park, HoYun Choi, Jong-min Baek, Han Dock Song, Sung Jin Jung, and Kun Jong Lee Research & Development Group, Wonik Materials Co, Ltd., Korea, 654-3, Gak-ri, Ochang-eup, Cheongwon-gun, Chungcheongbuk-do363-885, Republic of Korea ABSTRACT: Isothermal vapor−liquid equilibrium (VLE) data were measured for the binary systems of octafluoropropane + octafluorocyclobutane and hexafluoropropylene oxide + octafluorocyclobutane system at the temperature range from 263.15 K to 303.15 K. The experiments were carried out with a circulating-type equilibrium apparatus including online gas chromatography analysis. The VLE data were correlated well by the Peng− Robinson equation of state using the Wong−Sandler mixing rules involving the NRTL model. All the binary parameters of these systems and the average absolute deviations (AADs) in terms of saturated pressure and vapor phase composition between the experimental and calculated values are represented.

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INTRODUCTION As a result of the Montreal Protocol, some refrigerants such as chlorofluorocarbons (CFCs) have been widely phased out and replaced by an environment friendly substance such as hydrofluorocarbons (HFCs) and hydrocarbons (HCs).1,2 The largest amount of fluorinated gases is utilized by the semiconductor industry. The use of fluorinated process gases for plasma-based thin film processing applications has been an instrumental technique for driving the phenomenal growth in semiconductor manufacturing, which in turn has led to the development of the currently massive electronics industry. The replacement of wet chemistry processes with new dry processing technologies employing fluorine containing gases has enabled the increase of process automation during wafer manufacturing.3−5 Currently, there is an increasing number of alternative binary and ternary mixtures that can be used in CFC based appliances without the need for system modifications and that ensure safety in industrial and domestic applications. Alternatives for use in industry can be obtained by various means. Acquisition of vapor−liquid equilibrium (VLE) data is regarded as one of the most important fundamental strategies for evaluating the performance of the refrigeration cycle and determining the optimal composition of the employed mixtures. Although extensive binary vapor−liquid equilibrium data have been acquired for these mixtures,6,7 further evaluation is required to find substitutes and to evaluate the efficiency of these mixtures as working fluids in industrial machinery. In this work, we focused on mixtures comprising the octafluoropropane + octafluorocyclobutane and the hexafluoropropylene oxide + octafluorocyclobutane systems. Isothermal VLE data were acquired for the binary systems in the © 2014 American Chemical Society

temperature range of 263.15 K to 303.15 K. VLE data simulation employing traditional VLE models such as the Peng−Robinson equation of state (PR-EOS) was utilized to determine the extent of their predictive ability for the behavior of the highly nonideal binary systems. The experimental data were correlated with the PR-EOS using the Wong-Sandler mixing rules involving the NRTL model.

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EXPERIMENTAL SECTION Materials. The hexafluoropropylene oxide was supplied by Daikin Co., Ltd. (Japan) at a purity higher than 99.8 % mass. The octafluoropropane and octafluorocyclobutane were supplied by Wonik Materials Co., Ltd. (Korea) with a guaranteed purity higher than 99.9 % mass. These chemicals were used without any further purification in these experiments. Apparatus and Procedure. A circulation-type apparatus was utilized to measure isothermal vapor−liquid equilibria. The equipment had two high-pressure circulation pumps in which both vapor and liquid phases were continuously recycled in the system. Each circulation line included a vapor and liquid sampling valve for analysis. The schematic diagram and setup of the VLE apparatus is shown in Figure 1. The system consisted of a feed injection port, an equilibrium cell, circulation pumps, sampling valves, and a temperature-controlled water bath. Each sample for feed injection was measured by means of a balance (E0D120 model, Ohaus, Korea) in the feed injection port with an accuracy of ± 0.01 g. The volume of the stainless steel Received: December 30, 2013 Accepted: June 14, 2014 Published: June 24, 2014 2164

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equilibrium vessel, equipped with dual glass observation windows, was approximately 100 cm3. Vapor and liquidpumps (Hanyang Industry, Korea) were used to circulate the vapor and liquid. The pressure in the cell was measured using a pressure transducer (Crystal, USA) connected to a digital indicator (Autonics, Korea). The accuracy of the digital pressure gauge was ± 0.05 %. The temperature of the equilibrium cell in the water bath was maintained constant by an isothermal circulator. The six-port sampling valves (7413 model, Rheodyne, USA) were used for direct collection at the circulation point and the samples lines were connected to a gas chromatographe (600D model, Younglin, Korea) equipped with a flame ionization detector and a Porapak-Q column (15 ft long; 2.0 mm diameter; mesh range, 80/100, Agilent, USA). Sample data were analyzed using a computer program (Autochro-win, Younglin, Korea). Analysis of the binary mixtures using the above-described apparatus was performed by the following procedure. First, the entire system was evacuated using a vacuum pump to remove all of the inert gases. For the mixture of octafluoropropane + octafluorocyclobutane, an adequate amount of octafluorocyclobutane to offset the lower pressure than octafluoropropane was introduced into the cell from the sample reservoir as a preceding step. The temperature of the entire system was maintained constant by controlling the temperature of the water bath. After the desired temperature was attained, the pressure of the pure component was measured. An adequate amount of octafluoropropane for the binary octafluoropropane and octafluorocyclobutane mixture was supplied to the cell from a charging cylinder. The binary mixture in the cell was stirred continuously with a magnetic stirrer. Both the vapor and liquid phases were recirculated by the circulation pump until an equilibrium state was established. When the equilibrium was attained, the pressure was measured and vapor and liquid samples were then taken from the recycling lines by the vapor and liquid sampling valves. The compositions of the samples were measured by immediately injecting the samples into the

Figure 1. Schematic diagram (a) and setup (b) of the vapor−liquid equilibrium apparatus.

Table 1. Comparison of the Measured Pure Component Vapor Pressures with the Experimental Data of Vapor Pressure Used T component octafluoropropane

average hexafluoropropylene oxide

average octafluorocyclobutane

Pv,REFc

Pv,exp

|ΔPv/Pv,exp|b

K

MPa

MPa

MPa

%

263.15 273.15 283.15 293.15 303.15

0.3048 0.4252 0.5801 0.7796 1.0263

0.3050 0.4250 0.5800 0.7800 1.0250

−0.0002 0.0002 0.0001 −0.0004 0.0013

263.15 273.15 283.15 293.15 303.15

0.2151 0.3094 0.4301 0.5808 0.7712

0.2150 0.3100 0.4300 0.5800 0.7700

0.0001 −0.0006 0.0001 0.0008 0.0012

263.15 273.15 283.15 293.15 303.15

0.0854 0.1305 0.1902 0.2661 0.3711

0.0848 0.1303 0.1900 0.2650 0.3703

0.0006 0.0002 0.0002 0.0011 0.0008

0.066 0.047 0.017 0.051 0.127 0.015 0.047 0.194 0.023 0.138 0.156 0.034 0.703 0.153 0.105 0.413 0.216 0.318

average a

ΔPva

ΔPv = Pv,exp − Pv,REF. b|ΔPv/Pv,exp| = |(Pv,exp − Pv,REF)/Pv,exp| cReference 8. 2165

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Table 2. Vapor-liquid equilibrium measurements for the octafluoropropane (1) + octafluorocyclobutane (2) systema Pexp/MPa

x1,exp

y1,exp

Pcal/MPa

0.0854 0.1011 0.1234 0.1448 0.1682 0.2006 0.2262 0.2420 0.2917 0.2827 0.3048

0.0000 0.0907 0.2468 0.4240 0.5609 0.5926 0.7615 0.8177 0.9861 0.9675 1.0000

0.0000 0.1357 0.4006 0.5600 0.6698 0.7632 0.8438 0.8914 0.9975 0.9849 1.0000

0.1305 0.1572 0.1772 0.2041 0.2248 0.2655 0.2910 0.3185 0.3454 0.3882 0.4252

0.0000 0.1833 0.3290 0.4334 0.5296 0.5926 0.6726 0.7509 0.7979 0.9012 1.0000

0.0000 0.3201 0.5250 0.6182 0.6869 0.7252 0.7911 0.8516 0.8761 0.9326 1.0000

0.1902 0.1951 0.2137 0.2475 0.2827 0.3144 0.3558 0.4006 0.4392 0.4764 0.5192 0.5447 0.5564 0.5801

0.0000 0.0992 0.1808 0.2827 0.3677 0.4658 0.5755 0.6628 0.7129 0.8249 0.8831 0.9500 0.9395 1.0000

0.0000 0.2315 0.3209 0.4913 0.5915 0.6735 0.7281 0.7850 0.8368 0.8723 0.9174 0.9516 0.9600 1.0000

0.2661 0.2765 0.2972 0.3392 0.3861 0.4234 0.4778 0.5295 0.6399 0.6978 0.7796

0.0000 0.1540 0.2298 0.4024 0.4846 0.5682 0.6245 0.6838 0.8522 0.8954 1.0000

0.0000 0.2032 0.2966 0.4602 0.5668 0.6528 0.7142 0.7671 0.8730 0.9082 1.0000

0.3711 0.3751 0.3992 0.4523 0.5054 0.5606 0.7005 0.7695 0.8371

0.0000 0.0783 0.1294 0.2669 0.3671 0.4625 0.6307 0.7042 0.7716

0.0000 0.2507 0.3318 0.4394 0.5460 0.6218 0.7583 0.8044 0.8812

263.15 K 0.0879 0.1017 0.1212 0.1483 0.1760 0.1884 0.2283 0.2449 0.2963 0.2908 0.3002 273.15 K 0.1317 0.1531 0.1801 0.2059 0.2347 0.2561 0.2859 0.3173 0.3369 0.3809 0.4221 283.15 K 0.1910 0.2067 0.2232 0.2487 0.2746 0.3098 0.3559 0.3973 0.4226 0.4821 0.5139 0.5449 0.5489 0.5784 293.15 K 0.2692 0.2784 0.2908 0.3447 0.3843 0.4339 0.4719 0.5157 0.6522 0.6882 0.7750 303.15 K 0.3372 0.3643 0.3862 0.4589 0.5210 0.5937 0.7112 0.7669 0.8214 2166

ΔPb/MPa

y1,cal

Δy1c

0.0000 0.2018 0.4316 0.6486 0.7746 0.8113 0.9012 0.9328 0.9976 0.9988 1.0000

−0.0031 −0.0006 0.0022 −0.0035 −0.0078 0.0122 −0.0021 −0.0029 −0.0046 −0.0081 0.0048

0.0000 −0.0661 −0.0310 −0.0886 −0.1048 −0.0481 −0.0574 −0.0414 −0.0001 −0.0139 0.0000

0.0000 0.3029 0.5277 0.6538 0.7316 0.7812 0.8282 0.8815 0.9125 0.9655 1.0000

−0.0014 0.0041 −0.0029 −0.0018 −0.0099 0.0094 0.0051 0.0012 0.0085 0.0073 0.0029

0.0000 0.0172 −0.0027 −0.0356 −0.0447 −0.0560 −0.0371 −0.0299 −0.0364 −0.0329 0.0000

0.0000 0.1657 0.2994 0.4556 0.5719 0.6775 0.7618 0.8372 0.8684 0.9284 0.9560 0.9788 0.9818 1.0000

−0.0010 −0.0116 −0.0095 −0.0012 0.0081 0.0046 −0.0001 0.0033 0.0166 −0.0057 0.0053 −0.0002 0.0075 0.0016

0.0000 0.0658 0.0215 0.0357 0.0196 −0.0040 −0.0337 −0.0522 −0.0316 −0.0561 −0.0386 −0.0272 −0.0218 0.0000

0.0000 0.1965 0.3149 0.5166 0.6177 0.6982 0.7581 0.8080 0.9311 0.9536 1.0000

−0.0042 −0.0019 0.0064 −0.0055 0.0018 −0.0105 0.0059 0.0138 −0.0123 0.0096 0.0050

0.0000 0.0067 −0.0183 −0.0564 −0.0509 −0.0454 −0.0439 −0.0409 −0.0581 −0.0454 0.0000

0.0000 0.1420 0.2346 0.4590 0.5895 0.6882 0.8156 0.8585 0.8937

0.0331 0.0108 0.0130 −0.0066 −0.0156 −0.0331 −0.0107 0.0026 0.0157

0.0000 0.1087 0.0972 −0.0196 −0.0435 −0.0664 −0.0573 −0.0541 −0.0125

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Table 2. continued Pexp/MPa

x1,exp

0.8908 1.0263 a

y1,exp 0.8507 1.0000

Pcal/MPa 0.9104 1.0000

ΔPb/MPa

y1,cal

303.15 K 0.8864 1.0230

0.9316 1.0000

Δy1c −0.0212 0.0000

0.0044 0.0020

Standard uncertainties u are u(T) = 0.005 K, u(P) = 0.007 MPa and u(x) = u(y) = 0.01. bΔP = Pexp − Pcal cΔy1 = y1,exp − y1,cal

Table 3. Vapor−Liquid Equilibrium Measurements for the Hexafluoropropylene Oxide (1) + Octafluorocyclobutane (2) Systema

a

Pexp/MPa

x1,exp

y1,exp

0.0854 0.1048 0.1179 0.1282 0.1400 0.1834 0.2075 0.2151

0.0000 0.0937 0.1886 0.3255 0.4234 0.7792 0.8919 1.0000

0.0000 0.1301 0.2886 0.4459 0.5713 0.8559 0.9589 1.0000

0.1305 0.1510 0.1586 0.1731 0.2041 0.2434 0.2848 0.3094

0.0000 0.1290 0.1807 0.2932 0.4377 0.6503 0.8414 1.0000

0.0000 0.2361 0.3180 0.4526 0.6276 0.8033 0.9265 1.0000

0.1902 0.2144 0.2213 0.2620 0.2848 0.3082 0.3592 0.4068 0.4301

0.0000 0.1331 0.1890 0.3996 0.4982 0.5912 0.8038 0.9167 1.0000

0.0000 0.2578 0.3521 0.5975 0.6847 0.7602 0.8845 0.9713 1.0000

0.2661 0.3075 0.3379 0.3599 0.3923 0.4240 0.4585 0.5292 0.5808

0.0000 0.1965 0.3662 0.4439 0.5080 0.6652 0.7059 0.8559 1.0000

0.0000 0.3150 0.4639 0.5544 0.6467 0.7204 0.8586 0.9339 1.0000

0.3711 0.4061 0.4144 0.4813 0.5226 0.5613 0.6647 0.7712

0.0000 0.1381 0.1760 0.3984 0.4633 0.5452 0.7753 1.0000

0.0000 0.2933 0.3207 0.5389 0.6232 0.7114 0.8683 1.0000

Pcal/MPa 263.15 K 0.0879 0.1057 0.1154 0.1297 0.1411 0.1863 0.1955 0.2143 273.15 K 0.1317 0.1494 0.1575 0.1767 0.2033 0.2435 0.2792 0.3089 283.15 K 0.1909 0.2126 0.2227 0.2635 0.2842 0.3054 0.3638 0.4024 0.4328 293.15 K 0.2692 0.3067 0.3416 0.3618 0.3809 0.4373 0.4541 0.5217 0.5915 303.15 K 0.3672 0.3995 0.4119 0.4971 0.5214 0.54995 0.6582 0.7765

y1,cal

ΔPb/MPa

Δy1c

0.0000 0.2221 0.3412 0.5034 0.6112 0.8894 0.9287 1.0000

−0.0031 −0.0009 0.0025 −0.0015 −0.0011 −0.0029 0.0120 0.0007

0.0000 −0.0920 −0.0526 −0.0575 −0.0399 −0.0335 0.0302 0.0000

0.0000 0.2300 0.3138 0.4747 0.6387 0.8116 0.9234 1.0000

−0.0014 0.0016 0.0011 −0.0036 0.0008 −0.0001 0.0056 0.0011

0.0000 0.0061 0.0042 −0.0221 −0.0111 −0.0083 0.0031 0.0000

0.0000 0.2150 0.2957 0.5493 0.6479 0.7327 0.8993 0.9662 1.0000

−0.0009 0.0018 −0.0014 −0.0015 0.0006 0.0028 −0.0046 0.0044 −0.0028

0.0000 0.0428 0.0564 0.0482 0.0368 0.0275 −0.0148 0.0051 0.0000

0.0000 0.2770 0.4889 0.5815 0.6534 0.8057 0.8387 0.9370 1.0000

−0.0042 0.0008 −0.0037 −0.0019 0.0114 −0.0133 0.0044 0.0075 −0.0115

0.0000 0.0380 −0.0250 −0.0271 −0.0067 −0.0853 0.0199 −0.0031 0.0000

0.0000 0.2109 0.2669 0.5679 0.6459 0.7156 0.8806 1.0000

0.0031 0.0066 0.0025 −0.0158 0.0012 0.0118 0.0065 −0.0065

0.0000 0.0824 0.0538 −0.0290 −0.0227 −0.0042 −0.0123 0.0000

Standard uncertainties u are u(T) = 0.005 K, u(P) = 0.007 MPa and u(x) = u(y) = 0.01. bΔP = Pexp − Pcal. cΔy1 = y1,exp − y1,cal.

gas chromatograph that was connected to online vapor and liquid sampling valves. The gas chromatograph was calibrated with mixtures of known compositions that were prepared

gravimetrically. The equilibrium concentration was measured at least three times in sequence to obtain reliable average values for each phase and the average values were considered to 2167

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correspond to the equilibrium values. The gas chromatograph was calibrated with mixtures of known composition that were prepared gravimetrically. Considering the margin of error and the reproducibility of gas chromatography, the overall uncertainty in the measurements of the composition was estimated to be within ± 0.01 for the mole fraction for both the liquid and vapor phases. An adequate amount of octafluorocyclobutane was also introduced into the cell prior to the injection of hexafluoropropylene oxide for the binary mixture of hexafluoropropylene oxide and octafluorocyclobutane. The experiments were then performed using the same procedure and analysis described above.

Table 4. Characteristic Properties of Chemicals Used in This Work

a

(2)

b = 0.077796RTc/Pc

(3)

α(T ) = [1 + κ(1 −

2

Tr )]

κ = 0.37464 + 1.54226ω − 0.26992ω 2

ωa

0.999 0.998 0.999

345.1 357.1 388.4

2.680 2.840 2.784

0.326 0.364 0.356

Reference 15.

bm =

∑i ∑j xixj(b − (a /RT ))ij 1 − (A∞E /CRT ) − ∑i xiai /RTbi)

(6)

with (b − a /(RT ))ij = 0.5[(b − a /(RT ))i + (b − a /(RT ))j ](1 − kij)

(7)

and am = bm

∑ xi i

ai AE + ∞ bi C

(8)

where C is a constant equal to ln (√2 − 1)/√2 for the PREOS; kij is a binary interaction parameter, AE∞ is an excess Helmholtz free energy model at infinite pressure. Because the excess Helmholtz free energy of mixing at infinite pressure is assumed equal to the excess Gibbs free energy(GE) at low pressure. In this work, we used the NRTL model11,13 given by E A∞ = (RT )

∑ xi i

∑j xjGjiτji ∑k xkGki

(9)

with Gji = exp( −αijτji) and τij = Aij /(RT )

(10)

where Gij is the local composition factor for the NRTL model, τij is the NRTL model binary interaction parameter, Aij = (gij − gjj), gij is an interaction energy parameter of the i−j interaction, and R is the universal gas constant (8.314 J K−1 mol−1). αij has been set to 0.3 for these binary mixtures as the nonrandomness parameter. Also, the parameters of these equations were obtained by minimizing the following objective function (OF):

(1)

a = (0.457235R2Tc2/Pc)α(T )

Pc/MPa

pure components. These mixing rules for a cubic equation of state can be written as

RESULTS AND DISCUSSION The saturated vapor pressures (Pv) at various temperatures of pure octafluoropropane, hexa-fluoropropylene oxide, and octafluorocyclobutane obtained in this work and the experimental data8 are introduced in Table 1. Comparison indicated that the absolute deviations of vapor pressure (ΔPv) between the experimental and cited data were within ± 0.0004, ± 0.0006, and 0.0006 MPa for octafluoropropane, hexafluoropropylene oxide, and octafluorocyclobutane, respectively. The average relative deviations (ΔPv/Pv) were 0.015 % for octafluoropropane, 0.034 % for hexafluoropropylene oxide and 0.318 % for octafluorocyclobutane. The experimental VLE data for the binary mixtures, octafluoropropane + octa-fluorocyclobutane and hexafluoropropylene oxide + octafluorocyclobutane, were obtained at the temperature range from 263.15 K to 303.15 K and presented in Table 2 and Table 3. These tables list the measured mole fraction of the liquid (x1) and vapor phases (y1), pressures and temperatures in equilibrium and the deviations between measured and calculated pressure (ΔP) and vapor compositions (Δy). In this study, the experimental data of the binary systems were correlated by the PR-EOS using the Wong−Sadler mixing rules. The Peng−Robinson equation of state (PR-EOS)9 combined with the Wong−Sadler mixing rule, in which the excess Gibbs free energy(GE) at infinite pressure was represented by the NRTL equation.10−13 The PR-EOS and the Wong−Sadler mixing rules are expressed follows: a(T ) RT − v−b v(v + b) + b(v − b)

Tc/K

octafluoropropane hexafluoropropylene oxide octafluorocyclobutane

■

P=

mole fraction purity

1 OF = N

⎡⎛ P − P ⎞ ⎤ 2 i ,exp i ,cal ⎟⎟100⎥ ∑ ⎢⎢⎜⎜ P ⎠ ⎥⎦ i ,exp i = 1 ⎣⎝ N

(11)

where N is the number of experimental points, Pi,exp and Pi,cal are the experimental and calculated pressure data. On the P− x−y diagram shown in Figure 2 and Figure 3 with calculated VLE data at 263.15 K, 273.15 K, 283.15 K, 293.15 K, and 303.15 K. The experimental data and calculated values by using the PR-EOS model show good agreement. All the binary parameters of these systems and the average absolute deviations (AADs) in terms of saturated pressure and vapor phase composition between the experimental and calculated values are represented in Table 5. It was found that the values of AAD %-P and AAD%-y varied within 0.179 % and 4.953 % for the octafluoropropane + octafluorocyclobutane system and 0.380 % and 4.273 % for the hexafluoropropylene oxide + octafluor-

(4) (5)

where the parameter α is a function of temperature, b is a constant, κ is a constant characteristic of each substance, ω is the acentric factor, P is pressure, Pc is the critical pressure, Tc is the critical temperature, Tr is the reduced temperature, and υ is the molar volume. The critical properties (Pc, Tc), acentric factors (ω) are listed in Table 4 and used to calculate the parameters for the PR-EOS. The Wong−Sandler mixing rule14 was used to obtain equation of state parameters for a mixture from those of the 2168

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Table 5. Binary Parameters and Average Absolute Deviations k12a

T/K

AAD-Pb (%)

AAD-yc (%)

Octafluoropropane + Octafluorocyclobutane System 263.15 −0.5817 0.119 13.70 273.15 −0.0149 0.154 0.431 283.15 −0.0087 0.049 5.392 293.15 −0.1306 0.247 1.011 303.15 −0.1436 0.327 4.230 average 0.179 4.953 Hexafluoropropylene Oxide + Octafluorocyclobutane System 263.15 −0.2579 0.706 9.735 273.15 −0.1227 0.501 2.819 283.15 −0.3764 0.070 1.021 293.15 −0.3604 0.050 4.927 303.15 −0.0088 0.575 2.865 average 0.380 4.273 a Interaction parameters (k12). bAAD-P% = 1/N ∑iN= 1 |((Pi,cal − Pi,exp)/ (Pi,exp))|100. cAAD-y% = 1/N ∑i N= 1 |((yi,cal − yi,exp)/(yi,exp))|100.

range from 263.15 K to 303.15 K were carried out by using a circulation-type equilibrium apparatus. The correlation of results was obtained as the deviation of pressure and vapor composition between the experimental and the calculated data was less than 0.179 % and 4.953 % for the octafluoropropane + octafluorocyclobutane and 0.380 % and 4.273 % for the hexafluoro-propylene oxide + octafluorocyclobutane system. The PR-EOS using the Wong−Sandler mixing rules combined with the NRTL model was used to the fit experimental data and good agreement with the measured data at various temperatures was observed.

Figure 2. Vapor−liquid equilibrium of the octafluoropropane (1) + octafluorocyclobutane (2) system: −, PR EOS using the Wong− Sandler mixing rules at ▲, 263.15 K; ●, 273.15 K; ■, 283.15 K; ▼, 293.15 K; ◆, 303.15 K.

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Tel.: +82-43-2104412. Funding

The authors acknowledge the financial support by the Ministry of Knowledge Economy Foundation of Korea (T100100292). Notes

The authors declare no competing financial interest.

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REFERENCES

(1) Hu, P.; Chen, L.-X.; Chen, Z.-S. Vapor−liquid equilibria for the 1,1,1,2-tetrafluoroethane (HFC-134a) + 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea) and 1,1,1-trifluoroethane (HFC-143a) + 2,3,3,3tetrafluoroprop-1-ene (HFO-1234yf) systems. Fluid Phase Equilib. 2013, 360, 293−297. (2) Lim, J. S.; Park, J.-Y.; Kang, J. W.; Lee, B.-G. Measurement of vapor−liquid equilibria for the binary systems of propane + 1,1,1,2tetrafluoroethane and 1,1,1-trifluoroethane + propane at various temperatures. Fluid Phase Equilib. 2006, 243, 57−63. (3) Radoiu, M.; Hussain, S. Microwave plasma removal of sulphur hexafluoride. J. Hazard. Mater. 2009, 164, 39−45. (4) Tsai, W.-T. Environmental and health risks of chlorine trifluoride (ClF3), an alternative to potent greenhouse gases in the semiconductor industry. J. Hazard. Mater. 2011, 190, 1−7. (5) Allgood, C. C. Fluorinated gases for semiconductor manufacture: Process advances in chemical vapor deposition chamber cleaning. J. Fluorine Chem. 2003, 122, 105−112. (6) Lim, J. S.; Jin, J. M.; Yoo, K.-P. VLE measurement for binary systems of CO2 + 1,1,1,2-tetrafluoroethane (HFC-134a) at high pressures. J. Supercrit. Fluids 2008, 44, 279−283. (7) Yun, Y.; Im, J.; Shin, M. S.; Lee, Y.-W.; Kim, H. Vapor−liquid equilibria of the 1,1-difluoroethane (HFC-152a) + isobutene system. Fluid Phase Equilib. 2008, 271, 34−37.

Figure 3. Vapor−liquid equilibrium of the hexafluoropropylene oxide (1) + octafluorocyclobutane (2) system: −, PR EOS using the Wong− Sandler mixing rules at ▲, 263.15 K; ●, 273.15 K; ■, 283.15 K; ▼, 293.15 K; ◆, 303.15 K.

ocyclobutane system, respectively. From this table and the low average deviations of P and y, we conclude that the calculated values using the PR-EOS give good agreement with the experimental data.

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CONCLUSIONS Measurements of the VLE for the binary mixture of octafluoropropane + octafluoro-cyclobutane and hexafluoropropylene oxide + octafluorocyclobutane at the temperature 2169

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Article

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