Article
Chemistry, Physical
Vivian Walter Barron, Chin W. Yong, Alex Slowey, Ilian T. Todorov, Kevin J. Roberts, Robert B. Hammond
Summary: This study employs molecular modelling approaches to evaluate the effects of weak hydrogen bonding and steric repulsions on the molecular structure of 1,1,1,2-tetrafluoroethane (HFA-134a) in its solid and liquid states. The results indicate that weak hydrogen bonding is more common in the liquid state at lower temperatures, while structural ordering is mainly caused by steric repulsions. Understanding the structure of pure propellant is valuable for evaluating wetting variations in different formulation materials and may be a useful resource for digital drug product design.
JOURNAL OF MOLECULAR LIQUIDS
(2023)
Article
Chemistry, Multidisciplinary
Tianyi Song, Jinhai Zhang, Wei Li, Jie Ma, Shen Hu, Jianxiu Liu, Xiaonan Li, Wenfeng Hu, Chunming Lan, Guohua Tian, Tingxiang Jin, Yuexin Han, Jiancheng Wang, Junjie Gong, Chuanxiao Cheng
Summary: This study investigates the effects of R134a on the formation of CO2 hydrate using a visual experimental system. The results show that the addition of trace R134a significantly increases the conversion rate of CO2 hydrate and enhances gas consumption. It is also found that the R134a/CO2 mixed hydrate formed under the action of SDS has a capillary mechanism, promoting the formation of CO2 hydrate.
Article
Thermodynamics
Xiao Zhang, Liang Cai, Yu Liang, Zhenxi Ma, Xiaosong Zhang
Summary: The feasibility of combining novel halogenated hydrocarbon-based working pairs with low-pressure compression-assisted absorption refrigeration system (LCARS) was proven by experimental analysis. A prototype of the hybrid refrigeration system with the capacity of 1 kW was designed and tested using R134a-DMETEG as the working pair, demonstrating improved performance in LCARS compared to the single-stage absorption refrigeration system (SSARS). The study showed that LCARS increased the coefficient of performance (COP) by up to 91.04% and efficiently utilized lower-grade heat sources, offering a feasible technical approach for the application of absorption systems in safety-critical and lightweight scenarios.
APPLIED THERMAL ENGINEERING
(2023)
Article
Engineering, Marine
Shi Shen, Lei Wang, Yang Ge, Jiawei Chu, Huiyong Liang
Summary: The first prerequisite for the efficient and safe exploitation of gas hydrate resources is to accurately analyze the primary mechanical performance of hydrate-bearing sediments. This study found that the strength of HBSs decreased with increasing salinity. Moreover, the effect of the phase equilibrium of hydrates on the mechanical performance of HBSs was further explored.
JOURNAL OF MARINE SCIENCE AND ENGINEERING
(2023)
Article
Mathematics
Marat K. Khasanov, Svetlana R. Kildibaeva, Maxim V. Stolpovsky, Nail G. Musakaev
Summary: The article presents a mathematical model for the process of injecting methane into a natural reservoir to form gas hydrate, considering various factors. It reveals the regularities of the non-equilibrium formation of gas hydrate in a natural reservoir.
Article
Chemistry, Physical
Akinori Hoshikawa
Summary: Neutron diffraction measurements revealed a significant structural change in deuterated ethane hydrate below 30K, resulting in a new hexagonal crystal structure with ordered ethane molecules.
CHEMICAL PHYSICS LETTERS
(2022)
Article
Energy & Fuels
Vyacheslav G. Smirnov, Andrey Y. Manakov, Zinfer R. Ismagilov
Summary: A new equation describing the equilibrium conditions for gas hydrate in thin pores of mesoporous materials is proposed in this study. The equation takes into account the size of hydrate particles together with the chemical potential of pore water in equilibrium with the hydrate. The modeling results are in reasonable qualitative agreement with the experimental data.
Article
Engineering, Chemical
Tao Yang, J. Ilja Siepmann, Jiangtao Wu
Summary: The VLE properties and microscopic structures of alternative hydrofluorocarbon refrigerant mixtures were investigated through redesigning experimental apparatus, utilizing various models and simulation methods. The study achieved good agreement with experimental results by combining different approaches.
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
(2021)
Article
Thermodynamics
Chuanxiao Cheng, Zhengxiang Lai, Tingxiang Jin, Zhiyong Jing, Wangning Geng, Tian Qi, Shiquan Zhu, Jun Zhang, Jianxiu Liu, Fan Wang, Hongsheng Dong, Lunxiang Zhang
Summary: A new method based on self-circulation of tetrafluoroethane boiling-condensation process was proposed to promote rapid nucleation and growth of hydrates. Experimental results showed that this method increased the rate of hydrates formation by 4000 times and obtained the optimum hydrate formation condition.
Article
Thermodynamics
Aaron J. Rowane, Richard A. Perkins
Summary: This paper reports the speed of sound data measured using a dual-path pulse-echo instrument for binary mixtures of 1,1,1,2-tetrafluoroethane (R-134a), 2,3,3,3-tetrafluoropropene (R-1234yf), and trans-1,3,3,3-tetrafluoropropene (R-1234ze(E)). The results show that the measured speed of sound has small uncertainty within a certain range of temperature and pressure. The reported data are compared to existing models and further adjustments are needed for better representation of the experimental data.
JOURNAL OF CHEMICAL AND ENGINEERING DATA
(2022)
Article
Energy & Fuels
Hao Liang, Yonggang Duan, Jun Pei, Na Wei
Summary: This study investigates the phase equilibrium of natural gas hydrate using the Kvamme-Tanaka statistical thermodynamic model, revealing that the phase equilibrium curves are related to the guest molecule type and gas composition. The evolution of phase equilibrium pressure of different gases varies with temperature and composition, with the phase splitting of CO2 at the quadruple point affecting the equilibrium conditions. The model shows good performance in predicting phase equilibrium, with low mean square error values for various gas systems.
FRONTIERS IN ENERGY RESEARCH
(2021)
Article
Geochemistry & Geophysics
Takayuki Ishii, Artem Chanyshev, Tomoo Katsura
Summary: The Clapeyron slope is essential for understanding mantle dynamics and evolution. Previous experiments had issues in accurately determining phase boundaries. A recent study developed a novel approach using X-ray diffraction intensity, providing an accurate and precise phase boundary.
Article
Chemistry, Physical
Ningru Sun, Yanjun Li, Nianxiang Qiu, Joseph S. Francisco, Shiyu Du
Summary: Hydrate Based Gas Separation (HBGS) technology is being developed as a solution for air pollution caused by flue gas. The study shows that the presence of H2S, SO2, and N2O in mixed gases can promote the formation of CO2 hydrate, and the ratio between CO2 and impurity gases can predict the gas recovery yield under different conditions.
JOURNAL OF MOLECULAR LIQUIDS
(2023)
Article
Chemistry, Physical
Sahebeh Yousefi, Masoud Bahrami, Seyed Hesam Najibi
Summary: The dissociation conditions of CO2-C3H8 hydrate in concentrated NaCl solutions were measured, and the promoting effect of propane and its balance with the inhibitory effect of NaCl were observed. Three thermodynamic models were applied to predict the experimental data, with the PR model showing the best accuracy.
JOURNAL OF MOLECULAR LIQUIDS
(2023)
Article
Engineering, Chemical
Xin Chen, Huazhou Li
Summary: This study aims to tune the Kihara potential parameters to establish a robust and accurate van der Waals-Platteeuw (vdW-P) model for gas hydrates. Parameters were optimized using experimental data, resulting in improved modeling of pure-gas hydrates and more accurate predictions for gas mixtures in hydrate equilibria. The vdW-P hydrate model combined with the newly fitted Kihara potential parameters can effectively detect hydrate structure transitions and cage occupancy behaviors.
CHEMICAL ENGINEERING SCIENCE
(2022)
Article
Thermodynamics
Shunsuke Hashimoto, Koichi Kurazono, Takafumi Yamauchi
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2020)
Article
Engineering, Chemical
Jin Shimada, Masami Shimada, Takeshi Sugahara, Katsuhiko Tsunashima, Yuta Takaoka, Atsushi Tani
Summary: This study investigated the impact of cation size and shape on the thermodynamic properties of semiclathrate hydrates, finding that branched alkyl groups raised the equilibrium temperature while shorter alkyl groups lowered it. Among the orthorhombic systems studied, semiclathrate hydrates with higher equilibrium temperatures had larger dissociation enthalpies.
CHEMICAL ENGINEERING SCIENCE
(2021)
Article
Thermodynamics
Shunsuke Hashimoto, Kazuhisa Yano, Yasuki Hirota, Hiroshi Uchiyama, Satoshi Tsutsui
Summary: The study demonstrates that adding a small amount of SiO2 nanoparticles to nanofluids can enhance thermal conductivity beyond theoretical values, and the high-frequency sound velocity can provide insights into the relationship between solvent molecular relaxation and thermal conductivity. Different sizes of SiO2 particles have varying effects on the high-frequency sound velocity and thermal conductivity of ethylene glycol aqueous solution.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Thermodynamics
Jin Shimada, Moe Yamada, Atsushi Tani, Takeshi Sugahara, Katsuhiko Tsunashima, Yusuke Tsuchida, Takayuki Hirai
Summary: The thermodynamic properties of SCHs are influenced by the steric conformations of the guest anions. Different guest anions have varying effects on the equilibrium temperatures of SCHs, with some exhibiting similar temperatures while others show higher temperatures. Anion size and conformation play a critical role in determining the stability and properties of SCHs.
JOURNAL OF CHEMICAL AND ENGINEERING DATA
(2022)
Article
Chemistry, Physical
Shunsuke Hashimoto, Kenji Nakajima, Tatsuya Kikuchi, Kazuya Kamazawa, Kaoru Shibata, Takeshi Yamada
Summary: QENS and PFG-NMR analyses were performed on a nanofluid containing SiO2 nanoparticles and ethylene glycol aqueous solution. The results showed that SiO2 particles may decrease the self-diffusion coefficient of liquid molecules, leading to an increase in thermal conductivity of the nanofluid.
JOURNAL OF MOLECULAR LIQUIDS
(2021)
Article
Thermodynamics
Sakura Azuma, Jin Shimada, Katsuhiko Tsunashima, Takeshi Sugahara, Atsushi Tani, Takayuki Hirai
Summary: The present study investigates the thermodynamic stability of semiclathrate hydrates (SCHs) of tri-n-butylalkenylphosphonium bromide (P444(alkenyl)-Br: alkenyl = 3-butenyl (3.1) or 4-pentenyl (4.1)). The introduction of double bonds is found to lower the equilibrium temperature of the SCHs and affect their dissociation enthalpy.
JOURNAL OF CHEMICAL AND ENGINEERING DATA
(2022)
Article
Engineering, Chemical
Shunsuke Hashimoto, Takafumi Yamauchi
Summary: This study evaluates the heat transfer coefficients and friction factors of nanofluids composed of ethylene glycol aqueous solution and oxide-ceramic nanoparticles in a resistive-heated cylindrical channel. The experimental results show that the measured heat transfer coefficients are higher than the estimated coefficients based on the nanofluids' thermophysical properties. The difference between the experimental and estimated coefficients follows the order of the absolute zeta potential value of the nanofluids, indicating the importance of particle dispersibility. The heat exchange output in the nanofluids is in agreement with the order of their zeta potential values.
JOURNAL OF CHEMICAL ENGINEERING OF JAPAN
(2022)
Article
Chemistry, Physical
Shunsuke Hashimoto, Satoshi Yamaguchi, Masashi Harada, Kenji Nakajima, Tatsuya Kikuchi, Kazuki Ohishi
Summary: In recent research, it has been found that nanofluids composed of base liquids and dispersed solid nanoparticles show an anomalous improvement in thermal conductivity compared to the predicted value. By using various techniques, the study provides solid evidence that the vibrational behavior of liquid molecules around nanoparticles contributes significantly to the increased thermal conductivity. The vibration of liquid molecules is found to be equivalent to phonon conduction in solids, leading to a solid-like behavior in the liquid.
JOURNAL OF COLLOID AND INTERFACE SCIENCE
(2023)
Article
Chemistry, Multidisciplinary
Sakura Azuma, Jin Shimada, Katsuhiko Tsunashima, Takeshi Sugahara, Takayuki Hirai
Summary: In this study, a novel type of ionic clathrate hydrate with high equilibrium temperature and dissociation enthalpy was developed for thermal storage applications.
NEW JOURNAL OF CHEMISTRY
(2022)
Article
Thermodynamics
Jin Shimada, Masami Shimada, Sakura Azuma, Takeshi Sugahara, Katsuhiko Tsunashima, Takayuki Hirai
Summary: The phase equilibrium (temperature-composition) relations of the TBP-TFA + water binary system were investigated, including solid-liquid and liquid-liquid equilibria. The phase diagram of TBP-TFA SCH showed peritectic behavior, with a decomposition temperature of 275.9 +/- 0.1 K and a stoichiometric composition of 0.027 +/- 0.002 mole fraction. The decomposition enthalpy of TBP-TFA SCH was determined to be 199 +/- 2 J/g. Above the LCST, liquid-liquid phase separation occurred, and the composition at the LCST was found to be similar to the stoichiometric composition of TBP-TFA SCH, indicating similar cluster-based solution structures.
FLUID PHASE EQUILIBRIA
(2023)
Article
Physics, Applied
Jin Shimada, Atsushi Tani, Takeshi Yamada, Takeshi Sugahara, Takayuki Hirai, Takuo Okuchi
Summary: The dynamics of water molecules in tetra-n-butyl-d36-ammonium bromide semiclathrate hydrate were studied, revealing a fast reorientation motion of water molecules in the temperature range of 212-278 K. The mean jump distance of hydrogen atoms was found to be within 1.5-2.0A degrees, with a relaxation time of 100-410 ps and an activation energy of 10.2 +/- 5.8 kJ/mol. This short relaxation time is possibly due to the strong interaction between a bromide anion and its surrounding water molecules, suggesting a unique strategy for designing efficient, safe, and inexpensive proton conductors using semiclathrate hydrates.
APPLIED PHYSICS LETTERS
(2023)
Article
Thermodynamics
Kazuhiro Minamikawa, Jin Shimada, Takeshi Sugahara, Takayuki Hirai
Summary: This study investigates environmentally friendly semiclathrate hydrates (SCHs) and finds that they are suitable phase change materials for cold energy storage. They can be used as refrigerants in the logistics of vegetables and fruits to preserve their freshness.
JOURNAL OF CHEMICAL AND ENGINEERING DATA
(2023)
Article
Chemistry, Multidisciplinary
Hironobu Machida, Takeshi Sugahara, Izumi Hirasawa
Summary: This study investigated the effect of various additives on the degree of supercooling in the formation of THF hydrate. It was found that adding AgO or Ag3PO4 can effectively reduce the degree of supercooling. Raman spectra and scanning transmission electron microscopy revealed that AgO or Ag3PO4 can form coordination bonds with THF molecules and accelerate cluster formation, thus diminishing the supercooling.
Article
Chemistry, Physical
Kouji Maeda, Masato Moritoki, Shinji Yae, Keisuke Fukui, Naoki Fukumuro, Takeshi Sugahara
Summary: The study found that pressurizing an AAA battery with Ar or N-2 at pressures of up to 5 MPa can significantly enhance its durability, even under high-current conditions. The research proposes a different reaction mechanism to explain how pressure affects the durability improvement.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Materials Science, Multidisciplinary
Hironobu Machida, Takeshi Sugahara, Izumi Hirasawa
Summary: Understanding the mechanism by which silver nanoparticles promote crystallization of supercooled aqueous solutions is crucial for designing semiclathrate hydrates for latent heat storage materials. This study reveals that silver nanoparticles accelerate cluster formation, leading to a phase change from supercooled droplets to ice grains. The discovery provides insights into heterogeneous nucleation during a phase change and has potential implications for enhancing production efficiency and quality of manufactured products.
COMMUNICATIONS MATERIALS
(2021)