The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
Zhongdi Duan - One of the best experts on this subject based on the ideXlab platform.
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A thermodynamic model for predicting transient pressure evolution in response to venting and vaporization of Liquefied Gas under sudden release.
Journal of hazardous materials, 2020Co-Authors: Zhongdi Duan, Guoliang Ding, Wenyong Tang, Tao RenAbstract:Liquefied Gases in energy supply chain suffer the risks of disastrous accidents (e.g. boiling liquid expanding vapor explosion) normally resulted from a sudden release. The boiling response and its associated pressure transient under sudden release determine the severity of the accident, and are crucial for assessing the consequences of the sudden release. For predicting the pressure transient, a thermodynamic model of the Liquefied Gas under sudden release is presented in this paper. A three-stage modelling approach is proposed to describe the entire thermodynamic process after sudden release according to the venting and boiling behaviors of Liquefied Gas. A set of differential-algebraic equations are established based on mass and energy conservation for predicting the transient thermodynamic parameters. Comparisons of model predictions with experimental data show a consistent trend in pressure-time histories, with relative deviations of average pressures less than 5.78 %. The results show that the minimum pressure point has a time delay compared to the boiling inception point. The increase of release pressure and the decrease of vessel scale will strengthen the pressure rebound, and the increase of vent area will lead to higher depressurization and re-pressurization rate.
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suppression effects of micro fin surface on the explosive boiling of Liquefied Gas under rapid depressurization
Journal of Hazardous Materials, 2019Co-Authors: Zhongdi Duan, Guoliang DingAbstract:Abstract The boiling liquid expanding vapor explosion (BLEVE) is a most severe hazard in Liquefied Gas storage and transportation, and its prevention depends on the suppression of the explosive boiling during tank depressurization. This paper proposes an idea of using micro-fin type surface to suppress the explosive boiling, and experimentally investigates the suppression mechanisms and quantitative effects on the explosive boiling. In the experiments, the bubble behaviors on a micro-fin and a smooth surface are observed for phenomenal analysis, and the explosive boiling consequences of the two surfaces are measured for quantitative evaluation. The results show that, the micro-fin surface brings forward the nucleation onset and reduces the boiling region, resulting in a weakened explosive boiling process. Among release pressures of 200 kPa-500 kPa and vent areas of 1.8 cm2-5.3 cm2, the adopted micro-fin surface reduces the boiling-induced pressure rise and the released energy by up to 24.5% and 35.6%, respectively.
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Experimental and modeling studies on the transient pressurization in response to boiloff vapor recondensation in Liquefied Gas storage tanks
Experimental Thermal and Fluid Science, 2017Co-Authors: Zhongdi Duan, Tao Ren, Guoliang DingAbstract:Abstract The boiling liquid expanding vapor explosion (BLEVE) is a most common hazard in Liquefied Gas storage and transportation. The explosion is resulted from tank overpressure under external thermal attack, and its prevention depends on accurate prediction of the boiling liquid pressurization. This paper presents a mathematical model to simulate the boiling liquid pressurization in Liquefied Gas storage tank. The model includes a semi-empirical equation to calculate the critical subcooled degree at the onset of pressurization, an energy equation of bubble condensation to calculate the net vapor generation rate in storage tank, a thermal-response equation of the subcooled boiling liquid to calculate the transient temperature of bulk liquid, and an isochoric equation to predict the transient pressure of boiloff Liquefied Gas. Comparison of the model predictions with experimental data shows that the maximum deviations of the predicted transient pressure and temperature are within 15 kPa and 3 °C, respectively.
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A moving-boundary based dynamic model for predicting the transient free convection and thermal stratification in Liquefied Gas storage tank
International Journal of Thermal Sciences, 1Co-Authors: Zhongdi Duan, Haoran Sun, Cheng Cheng, Wenyong Tang, Hongxiang XueAbstract:Abstract Thermal stratification occurs frequently in Liquefied Gas storage tank due to inevitable heat leak or unexpected thermal attack, and has vital influence on equipment safety. For predicting the thermal stratification of Liquefied Gas, a comprehensive dynamic model of the thermodynamic process in Liquefied Gas storage tank is proposed in this paper. In the model, the transient free convection in the vicinity of tank walls is simulated by a set of integral equations using the moving boundary method; the thermal stratification is predicted based on the coupling effects of the free convection and interfacial heat-mass transfer; the pressure build-up in storage tank is calculated according to the thermal non-equilibrium response of the Liquefied Gas. Comparisons of model predictions and experimental results show consistent trends of the thermal stratification and pressure response under different heat fluxes and liquid fill levels. The results indicate that the free convection is enhanced by the development of boundary layer at the initial phase of tank heat-up, and subsequently impeded by the thermal stratification development; the penetration time for thermal stratification will be shortened with the increase of external heat fluxes, while the dimensionless penetration time expressed by the equivalent thermal diffusivity maintains almost constant under various external heat fluxes.
Jianyun Shi - One of the best experts on this subject based on the ideXlab platform.
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Experimental research on the effects of fluid and heater on thermal stratification of Liquefied Gas
Experimental Thermal and Fluid Science, 2013Co-Authors: Jianyun Shi, Jingjie Ren, Peng LiuAbstract:Abstract The thermal stratification of Liquefied Gas influences the equipment safety. To find the factors and principles governing the thermal stratification, a device was set up to simulate the thermal response of a Liquefied Gas tank. A small steel vessel was used to simulate the tank, and two working fluids were used: water and R22. The heating region and liquid level were precisely adjusted in the tests to simulate different accident conditions. The experimental results showed saturation pressure of the working fluid affected the thermal stratification when the liquid wall was heated solely. For the case the liquid and vapor wall were heated together, evident thermal stratifications formed both in R22 and water tests. The degree and duration of thermal stratification are affected by the intensity of heat loading on the surface liquid. It is concluded that nucleate boiling in the lower liquid has great power to eliminate the thermal stratification. When the nucleate boiling is suppressed by hydrostatic pressure or saturation pressure of the warm surface liquid, the thermal stratification can form and maintain by natural convection. The stratifying process can be explained by a natural convection model.
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experimental research on thermal stratification of Liquefied Gas in tanks under external thermal attack
Experimental Thermal and Fluid Science, 2012Co-Authors: Jianyun Shi, Xue YangAbstract:Abstract When Liquefied Gas tanks are exposed to fire, the temperature and pressure in tanks will increase and may cause boiling liquid expanding vapor explosion (BLEVE). According to relevant researches, the likelihood and the severity of BLEVE’s hazards are significantly affected by the thermal stratification of Liquefied Gas. In this research, a device was set up to simulate the thermal response of Liquefied Gas tank under external thermal attack. In the tests two funiform electric heaters were used to simulate the fire, and a small steel vessel was used to simulate the tank, and the Liquefied Gas was simulated by water. The fill level, the heater power and the heated area were adjusted in the tests to simulate different accident conditions. The results showed that the liquid temperature is nearly uniform when the liquid space wall was heated solely; however, the temperature stratification was obvious when the liquid and vapor space walls were heated simultaneously. Based on the experimental results, this paper discusses how the temperature stratification appears and fades away.
Daniel M. Davies - One of the best experts on this subject based on the ideXlab platform.
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A Safer, Wide-Temperature Liquefied Gas Electrolyte Based on Difluoromethane
Journal of Power Sources, 2021Co-Authors: Daniel M. Davies, Yangyuchen Yang, Ekaterina S. Sablina, Yijie Yin, Matthew Mayer, Yihui Zhang, Marco Olguin, Jungwoo Z. Lee, Dijo DamienAbstract:Abstract Development of safe electrolytes that are compatible with both lithium metal anodes and high-voltage cathodes that can operate in a wide-temperature range is a formidable, yet important challenge. Recently, a new class of electrolytes based on Liquefied Gas solvents has shown promise in addressing this issue. Concerns, however, have been raised on the pressure, flammability and low maximum operating temperature of these systems. Here, we endeavor to mitigate safety and practicality concerns by demonstrating an enhanced safety feature inherent in Liquefied Gas electrolytes and by showing the viability of using difluoromethane as a Liquefied Gas solvent which has lower pressure, lower flammability, and improved maximum operation temperature characteristics compared with fluoromethane. We create a custom-built setup to enable Liquefied Gas electrolyte characterization through Raman spectroscopy and supplement this with molecular dynamics (MD) simulations. The electrolyte shows good conductivity through a wide temperature range and compatibility with both the lithium metal anode and 4 V class cathodes. The demonstrated use of such alternative Liquefied Gas solvents opens a path towards the further development of high-energy and safe batteries that can operate in a wide-temperature range.
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Liquefied Gas electrolytes for wide-temperature lithium metal batteries
Energy & Environmental Science, 2020Co-Authors: Yangyuchen Yang, Daniel M. Davies, Ekaterina S. Sablina, Yijie Yin, Matthew Mayer, Yihui Zhang, Jungwoo Z. Lee, Minghao Zhang, Shen Wang, Oleg BorodinAbstract:The momentum in developing next-generation high energy batteries calls for an electrolyte that is compatible with both lithium (Li) metal anodes and high-voltage cathodes, and is also capable of providing high power in a wide temperature range. Here, we present a fluoromethane-based Liquefied Gas electrolyte with acetonitrile cosolvent and a higher, yet practical, salt concentration. The unique solvation structure observed in molecular dynamics simulations and confirmed experimentally shows not only an improved ionic conductivity of 9.0 mS cm−1 at +20 °C but a high Li transference number (tLi+ = 0.72). Excellent conductivity (>4 mS cm−1) was observed from −78 to +75 °C, demonstrating operation above fluoromethane's critical point for the first time. The Liquefied Gas electrolyte also enables excellent Li metal stability with a high average coulombic efficiency of 99.4% over 200 cycles at the aggressive condition of 3 mA cm−2 and 3 mA h cm−2. Also, dense Li deposition with an ideal Li–substrate contact is seen in the Liquefied Gas electrolyte, even at −60 °C. Attributed to superior electrolyte properties and the stable interfaces on both cathode and anode, the performances of both Li metal anode and Li/NMC full cell (up to 4.5 V) are well maintained in a wide-temperature range from −60 to +55 °C. This study provides a pathway for wide-temperature electrolyte design to enable high energy density Li–metal battery operation between −60 to +55 °C.
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High-Efficiency Lithium-Metal Anode Enabled by Liquefied Gas Electrolytes
Joule, 2019Co-Authors: Yangyuchen Yang, Daniel M. Davies, Ekaterina S. Sablina, Yijie Yin, Yihui Zhang, Marco Olguin, Jungwoo Z. Lee, Oleg Borodin, Chengcheng Fang, Xuefeng WangAbstract:Summary Among the several challenges to enable next-generation batteries is the development of an electrolyte that maintains a dendrite-free and high Coulombic efficiency lithium-metal anode over extended cell cycling. A new electrolyte solvation structure and transport mechanism is demonstrated in fluoromethane-based Liquefied Gas electrolytes with the introduction of additive amounts of tetrahydrofuran, which is shown to fully coordinate with the lithium cations and greatly enhance salt dissociation and transport. The resulting electrolyte shows a high conductivity and transference number (t+ > 0.79), which leads to a dramatic improvement of the cycling performance of the lithium-metal anode. Systems using the enhanced Liquefied Gas electrolytes demonstrate a long-term high average Coulombic efficiency of 99.6%, 99.4%, and 98.1% (± 0.3%) at capacities of 0.5, 1, and 3 mAh·cm−2, respectively, with dendrite-free morphology and remarkable rate capability. Both the rate and cycling performance are well maintained from +20°C to −60°C.
Yangyuchen Yang - One of the best experts on this subject based on the ideXlab platform.
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A Safer, Wide-Temperature Liquefied Gas Electrolyte Based on Difluoromethane
Journal of Power Sources, 2021Co-Authors: Daniel M. Davies, Yangyuchen Yang, Ekaterina S. Sablina, Yijie Yin, Matthew Mayer, Yihui Zhang, Marco Olguin, Jungwoo Z. Lee, Dijo DamienAbstract:Abstract Development of safe electrolytes that are compatible with both lithium metal anodes and high-voltage cathodes that can operate in a wide-temperature range is a formidable, yet important challenge. Recently, a new class of electrolytes based on Liquefied Gas solvents has shown promise in addressing this issue. Concerns, however, have been raised on the pressure, flammability and low maximum operating temperature of these systems. Here, we endeavor to mitigate safety and practicality concerns by demonstrating an enhanced safety feature inherent in Liquefied Gas electrolytes and by showing the viability of using difluoromethane as a Liquefied Gas solvent which has lower pressure, lower flammability, and improved maximum operation temperature characteristics compared with fluoromethane. We create a custom-built setup to enable Liquefied Gas electrolyte characterization through Raman spectroscopy and supplement this with molecular dynamics (MD) simulations. The electrolyte shows good conductivity through a wide temperature range and compatibility with both the lithium metal anode and 4 V class cathodes. The demonstrated use of such alternative Liquefied Gas solvents opens a path towards the further development of high-energy and safe batteries that can operate in a wide-temperature range.
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Liquefied Gas electrolytes for wide-temperature lithium metal batteries
Energy & Environmental Science, 2020Co-Authors: Yangyuchen Yang, Daniel M. Davies, Ekaterina S. Sablina, Yijie Yin, Matthew Mayer, Yihui Zhang, Jungwoo Z. Lee, Minghao Zhang, Shen Wang, Oleg BorodinAbstract:The momentum in developing next-generation high energy batteries calls for an electrolyte that is compatible with both lithium (Li) metal anodes and high-voltage cathodes, and is also capable of providing high power in a wide temperature range. Here, we present a fluoromethane-based Liquefied Gas electrolyte with acetonitrile cosolvent and a higher, yet practical, salt concentration. The unique solvation structure observed in molecular dynamics simulations and confirmed experimentally shows not only an improved ionic conductivity of 9.0 mS cm−1 at +20 °C but a high Li transference number (tLi+ = 0.72). Excellent conductivity (>4 mS cm−1) was observed from −78 to +75 °C, demonstrating operation above fluoromethane's critical point for the first time. The Liquefied Gas electrolyte also enables excellent Li metal stability with a high average coulombic efficiency of 99.4% over 200 cycles at the aggressive condition of 3 mA cm−2 and 3 mA h cm−2. Also, dense Li deposition with an ideal Li–substrate contact is seen in the Liquefied Gas electrolyte, even at −60 °C. Attributed to superior electrolyte properties and the stable interfaces on both cathode and anode, the performances of both Li metal anode and Li/NMC full cell (up to 4.5 V) are well maintained in a wide-temperature range from −60 to +55 °C. This study provides a pathway for wide-temperature electrolyte design to enable high energy density Li–metal battery operation between −60 to +55 °C.
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High-Efficiency Lithium-Metal Anode Enabled by Liquefied Gas Electrolytes
Joule, 2019Co-Authors: Yangyuchen Yang, Daniel M. Davies, Ekaterina S. Sablina, Yijie Yin, Yihui Zhang, Marco Olguin, Jungwoo Z. Lee, Oleg Borodin, Chengcheng Fang, Xuefeng WangAbstract:Summary Among the several challenges to enable next-generation batteries is the development of an electrolyte that maintains a dendrite-free and high Coulombic efficiency lithium-metal anode over extended cell cycling. A new electrolyte solvation structure and transport mechanism is demonstrated in fluoromethane-based Liquefied Gas electrolytes with the introduction of additive amounts of tetrahydrofuran, which is shown to fully coordinate with the lithium cations and greatly enhance salt dissociation and transport. The resulting electrolyte shows a high conductivity and transference number (t+ > 0.79), which leads to a dramatic improvement of the cycling performance of the lithium-metal anode. Systems using the enhanced Liquefied Gas electrolytes demonstrate a long-term high average Coulombic efficiency of 99.6%, 99.4%, and 98.1% (± 0.3%) at capacities of 0.5, 1, and 3 mAh·cm−2, respectively, with dendrite-free morphology and remarkable rate capability. Both the rate and cycling performance are well maintained from +20°C to −60°C.
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Liquefied Gas electrolytes for electrochemical energy storage devices
Science, 2017Co-Authors: Cyrus S Rustomji, Yangyuchen Yang, Tae Kyoung Kim, Jimmy Mac, Young Jin Kim, Elizabeth Caldwell, Hyeseung Chung, Shirley Y MengAbstract:Electrochemical capacitors and lithium-ion batteries have seen little change in their electrolyte chemistry since their commercialization, which has limited improvements in device performance. Combining superior physical and chemical properties and a high dielectric-fluidity factor, the use of electrolytes based on solvent systems that exclusively use components that are typically Gaseous under standard conditions show a wide potential window of stability and excellent performance over an extended temperature range. Electrochemical capacitors using difluoromethane show outstanding performance from -78° to +65°C, with an increased operation voltage. The use of fluoromethane shows a high coulombic efficiency of ~97% for cycling lithium metal anodes, together with good cyclability of a 4-volt lithium cobalt oxide cathode and operation as low as -60°C, with excellent capacity retention.
Guoliang Ding - One of the best experts on this subject based on the ideXlab platform.
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A thermodynamic model for predicting transient pressure evolution in response to venting and vaporization of Liquefied Gas under sudden release.
Journal of hazardous materials, 2020Co-Authors: Zhongdi Duan, Guoliang Ding, Wenyong Tang, Tao RenAbstract:Liquefied Gases in energy supply chain suffer the risks of disastrous accidents (e.g. boiling liquid expanding vapor explosion) normally resulted from a sudden release. The boiling response and its associated pressure transient under sudden release determine the severity of the accident, and are crucial for assessing the consequences of the sudden release. For predicting the pressure transient, a thermodynamic model of the Liquefied Gas under sudden release is presented in this paper. A three-stage modelling approach is proposed to describe the entire thermodynamic process after sudden release according to the venting and boiling behaviors of Liquefied Gas. A set of differential-algebraic equations are established based on mass and energy conservation for predicting the transient thermodynamic parameters. Comparisons of model predictions with experimental data show a consistent trend in pressure-time histories, with relative deviations of average pressures less than 5.78 %. The results show that the minimum pressure point has a time delay compared to the boiling inception point. The increase of release pressure and the decrease of vessel scale will strengthen the pressure rebound, and the increase of vent area will lead to higher depressurization and re-pressurization rate.
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suppression effects of micro fin surface on the explosive boiling of Liquefied Gas under rapid depressurization
Journal of Hazardous Materials, 2019Co-Authors: Zhongdi Duan, Guoliang DingAbstract:Abstract The boiling liquid expanding vapor explosion (BLEVE) is a most severe hazard in Liquefied Gas storage and transportation, and its prevention depends on the suppression of the explosive boiling during tank depressurization. This paper proposes an idea of using micro-fin type surface to suppress the explosive boiling, and experimentally investigates the suppression mechanisms and quantitative effects on the explosive boiling. In the experiments, the bubble behaviors on a micro-fin and a smooth surface are observed for phenomenal analysis, and the explosive boiling consequences of the two surfaces are measured for quantitative evaluation. The results show that, the micro-fin surface brings forward the nucleation onset and reduces the boiling region, resulting in a weakened explosive boiling process. Among release pressures of 200 kPa-500 kPa and vent areas of 1.8 cm2-5.3 cm2, the adopted micro-fin surface reduces the boiling-induced pressure rise and the released energy by up to 24.5% and 35.6%, respectively.
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Experimental and modeling studies on the transient pressurization in response to boiloff vapor recondensation in Liquefied Gas storage tanks
Experimental Thermal and Fluid Science, 2017Co-Authors: Zhongdi Duan, Tao Ren, Guoliang DingAbstract:Abstract The boiling liquid expanding vapor explosion (BLEVE) is a most common hazard in Liquefied Gas storage and transportation. The explosion is resulted from tank overpressure under external thermal attack, and its prevention depends on accurate prediction of the boiling liquid pressurization. This paper presents a mathematical model to simulate the boiling liquid pressurization in Liquefied Gas storage tank. The model includes a semi-empirical equation to calculate the critical subcooled degree at the onset of pressurization, an energy equation of bubble condensation to calculate the net vapor generation rate in storage tank, a thermal-response equation of the subcooled boiling liquid to calculate the transient temperature of bulk liquid, and an isochoric equation to predict the transient pressure of boiloff Liquefied Gas. Comparison of the model predictions with experimental data shows that the maximum deviations of the predicted transient pressure and temperature are within 15 kPa and 3 °C, respectively.
