Article pubs.acs.org/jced
Measurements of the Critical Parameters for cis-1,1,1,4,4,4Hexafluoro-2-butene Katsuyuki Tanaka,*,† Ryo Akasaka,‡ Eiichi Sakaue,§ Junichi Ishikawa,∥ and Konstantinos Kostas Kontomaris⊥ †
Department of Precision Machinery Engineering, Nihon University, Chiba, 274-8501, Japan Department of Mechanical Engineering, Kyushu Sangyo University, Fukuoka, 813-8503, Japan § Power System Company, Toshiba Co., Ltd., Kanagawa, 230-0045, Japan ∥ Dupont−Mitsui Fluorochemicals Co., Ltd., Tokyo, 101-0064, Japan ⊥ The Chemours Company, Wilmington, Delaware, 19898-1100, United States ‡
ABSTRACT: In this work, measurements of the critical parameters for cis-1,1,1,4,4,4hexafluoro-2-butene (HFO-1336mzz(Z)) were carried out by the meniscus disappearance method. Menisci were observed along five isochoric lines in the density range from 465 kg·m−3 to 536 kg·m−3, that is, near the critical density reported in our previous work. Critical opalescence was observed along all isochoric lines. The critical density was determined as the density at which the meniscus remained fixed with decreasing temperature. The critical temperature and critical pressure were determined from the observation of the meniscus disappearance with temperature increasing in 0.01 K intervals. The critical density, critical temperature, and critical pressure of HFO-1336mzz(Z) were determined to be 507 ± 5 kg·m−3, 444.50 ± 0.03 K, and 2895 ± 6 kPa, respectively.
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INTRODUCTION cis-1,1,1,4,4,4-Hexafluoro-2-butene (HFO-1336mzz(Z)) has been paid much attention as a potential working fluid for organic Rankine cycle (ORC) systems1−3 because this fluid has a very low global warming potential, is nonflammable, shows high thermal stability, and has attractive thermodynamic properties for many applications. Kontomaris presented some fundamental properties of HFO-1336mzz(Z), including chemical stability, safety, health, and environmental properties.2,3 Thermodynamic properties of HFO-1336mzz(Z), such as pρT property, vapor pressures, saturated densities, and critical parameters were also reported by our previous work.4 However, critical parameters were determined from analysis of pρT property data, so the uncertainty of the critical density was large. In this study, an apparatus for directly measuring the critical parameters was constructed, and measurements for HFO-1336mzz(Z) were carried out.
Figure 1. Schematic diagram of the apparatus: (A) optical cell, (B) pressure sensor, (C) expansion cell, (D) vacuum pump, (E, F) sample bottle, (G) pressure indicator, (H) temperature sensor, (I) temperature indicator, (J) thermostated oil bath, (K) silicon oil, (V) valve.
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bottle (F) before and after filling the cell. The mass of the sample bottle was measured by an electronic precision balance (Sartorius, MSE2203S). Before use, the sample was degassed by freeze−thaw cycling with liquid nitrogen. The sample density was obtained from the volume of the sample cell and the mass of sample in the cell. The temperature of the sample was controlled by a thermostatic oil bath (J) that can operate in the temperature range from 323 to 473 K (50 to 200 °C). The temperature of the oil bath was measured using a temperature
EXPERIMENTAL APPARATUS AND METHOD A schematic diagram of the experimental apparatus used in this work is shown in Figure 1. The apparatus employed the meniscus disappearance method. It used a constant volume optical cell (A) designed for operation in the temperature range from 323 to 453 K (50 to 180 °C) and at pressures up to 7 MPa. The optical cell was filled with the fluid of interest. The optical cell inner volume was approximately 93.21 cm3 at 444.50 K (171.35 °C) and was calibrated after the measurements for HFO-1336mzz(Z) using a fluid of known density, namely HFC-134a. The mass of fluid sample in the cell was determined from the difference in the masses of the sample © 2017 American Chemical Society
Received: November 27, 2016 Accepted: February 8, 2017 Published: February 16, 2017 1135
DOI: 10.1021/acs.jced.6b00990 J. Chem. Eng. Data 2017, 62, 1135−1138
Journal of Chemical & Engineering Data
Article
meniscus disappears with temperature increasing at 0.01 K intervals along the critical density isochor. Finally the critical pressure was determined by direct measurement at the critical temperature. The sample was supplied by The Chemours Company. The sample information is listed in Table 1. The combined expanded uncertainty (0.95 level of confidence) in the measured temperature value was estimated to be 0.03 K, because the expanded uncertainty of the thermometer, claimed by the manufacturer, was 0.026 K, and the maximum temperature fluctuation was 0.01 K. The combined expanded uncertainty (0.95 level of confidence) in the measured pressure value was estimated to be 6 kPa, because the expanded uncertainty of the calibrator, as specified by the manufacturer, was 5 kPa, and the maximum deviation in calibration was 1 kPa. The experimental uncertainty of the critical density was estimated using the density measurement interval Δρ with a triangle distribution u = Δρ/√6.
Figure 2. Schematic diagram of the behavior of the meniscus near the critical point.
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RESULTS AND DISCUSSIONS The meniscus was observed along densities and temperatures near 471 kg·m−3 and 444.42 K (171.27 °C), respectively, which were determined as the critical density and critical temperature by a previous work.4 The results of the meniscus observations with temperature decreasing continuously from 445.2 K (172.05 °C) for densities in the range from 465 kg·m−3 to 536 kg·m−3 are shown in Figure 3. Observations at all selected density values indicated a supercritical state at the starting temperature of 445.2 K (172.05 °C) and critical opalescence as the decreasing temperature approached the critical temperature. Upon further decreasing the fluid temperature below the critical temperature, a vapor−liquid meniscus appeared. Along the constant density of 536 kg·m−3, the location of the meniscus clearly moves downward with decreasing temperature. In contrast, along the constant density of 465 kg·m−3, the location of the meniscus clearly moves upward with decreasing temperature. Along the constant densities of 502 kg·m−3, 507 kg·m−3, and 513 kg·m−3, the meniscus locations remained almost fixed. The menisci movements for densities of 513, 507, and 502 kg·m−3 were carefully examined as shown in Figure 4. The meniscus along the density of 513 kg·m−3 moves slightly downward with decreasing temperature. In contrast, the meniscus along the density of 502 kg·m−3 moved slightly
Table 1. Sample Information
a
sample
CAS RN
purity
manufacturer
HFO-1336mzz(Z)a
692-49-9
99.95%
The Chemours Company
cis-1,1,1,4,4,4-Hexafluoro-2-butene.
sensor (H: CHINO, R900-F25AD). The pressure in the optical cell was measured using a pressure sensor (B: OMEGA, PX1009) that can operate in the temperature range from 220 to 616 K (−53 to 343 °C) and at pressures up to 7 MPa. The optical cell was illuminated by an LED light behind the cell and the meniscus of the sample in the optical cell can be observed through a window in the oil bath container by means of a digital camera located outside the oil bath. The meniscus was observed along isochoric lines over varying temperatures. The meniscus location shifts with temperature near the critical point as shown schematically in Figure 2. For densities higher than the critical density, the meniscus moves downward with decreasing temperature. For densities lower than the critical density, the meniscus moves upward with decreasing temperature. The critical density was determined as the density at which the location of the meniscus remains fixed with decreasing temperature. Then the critical temperature was determined as the temperature at which the
Figure 3. Meniscus observations with decreasing temperature. 1136
DOI: 10.1021/acs.jced.6b00990 J. Chem. Eng. Data 2017, 62, 1135−1138
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Figure 4. Meniscus observations with decreasing temperature at the densities of (a) 513 kg·m−3, (b) 507 kg·m−3, (c) 502 kg·m−3
distribution u = Δρ/√6, and then its expanded uncertainty U is U(ρc) = 5 kg·m−3 (0.95 level of confidence). The meniscus at the critical density of 507 kg·m−3 was observed as the temperature was increased from 444.43 K (171.28 °C) in intervals of 0.01 K, as shown in Figure 5. Critical opalescence was observed as the temperature approached the critical temperature. The meniscus became difficult to observe using a digital camera at 444.48 K (171.33 °C) and 444.49 K (171.34 °C), but remained visible to the naked eye. The temperature at which the meniscus disappeared, 444.50 K (171.35 °C) which was accepted as the critical temperature. The pressure measured at the critical temperature, 2895 kPa, was accepted as the critical pressure.
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Figure 5. Meniscus observations with increasing temperature at the density of 507 kg·m−3. *The meniscus disappeared in the photo, but visible to the naked eye. **The meniscus disappeared.
CONCLUSION
Measurements of the critical parameters for HFO-1336mzz(Z) were carried out with the meniscus disappearance method. The critical density, critical temperature, and critical pressure were determined to be 507 ± 5 kg·m−3, 444.50 ± 0.03 K, and 2895 ± 6 kPa, respectively. A Helmholtz energy equation of state is now being developed for HFO-1336mzz(Z) based on the critical parameters obtained in this work and previous extensive pρT measurements.4
upward with decreasing temperature. The location of the meniscus along the density of 507 kg·m−3 remained fixed. The critical density was determined to be 507 kg·m−3. The standard uncertainty of critical density u(ρc) is 2.5 kg·m−3 using the density measurement interval Δρ = 6 kg·m−3 with a triangle 1137
DOI: 10.1021/acs.jced.6b00990 J. Chem. Eng. Data 2017, 62, 1135−1138
Journal of Chemical & Engineering Data
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Article
AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected]. Tel.: +81−47−469−8396. Fax: +81−47−467−9504. ORCID
Katsuyuki Tanaka: 0000-0003-1042-3755 Funding
This work was supported by Nihon University College of Science and Technology Grants-in-Aid for Applied Science Research and supported by the Japan Science and Technology Agency (JST) under the Strategic International Collaborative Research Program (SICORP). Notes
The authors declare no competing financial interest.
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ACKNOWLEDGMENTS We thank to Mr. Nogami, graduate student in Nihon University, for his help with the measurements. REFERENCES
(1) Molés, F.; Navarro-Esbrí, J.; Peris, B.; Mota-Babiloni, A.; Barragán-Cervera, Á .; Kontomaris, K. Low GWP alternatives to HFC-245fa in Organic Rankine Cycles for low temperature heat recovery. HCFO-1233zd-E and HFO-1336mzz-Z. Appl. Therm. Eng. 2014, 71, 204−212. (2) Kontomaris, K., HFO-1336mzz-Z: High Temperature Chemical Stability and Use as a Working Fluid in Organic Rankine Cycles. 15th International Refrigeration and Air Conditioning Conference at Purdue, West Lafayette, IN, USA, 2014, Paper 1525. (3) Kontomaris, K.; Simoni, L. D.; Nilsson, M.; Hamacher, T.; Nes Rislå, H. Combined Heat and Power From Low Temperature Heat: HFO-1336mzz(Z) as a Working Fluid for Organic Rankine Cycles, 16th International Ref rigeration and Air Conditioning Conference at Purdue, 2016, Paper 2618, West Lafayette, IN, USA.. (4) Tanaka, K.; Akasaka, R.; Sakaue, E.; Ishikawa, J.; Kontomaris, K. Thermodynamic properties of cis−1,1,1,4,4,4−hexafluoro−2−butene (HFO−1336mzz(Z)): Measurements of the pρT Property and Determinations of Vapor Pressures, Saturated Liquid and Vapor Densities, and Critical Parameters. J. Chem. Eng. Data 2016, 61, 2467− 2473.
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DOI: 10.1021/acs.jced.6b00990 J. Chem. Eng. Data 2017, 62, 1135−1138
