The Experts below are selected from a list of 2031 Experts worldwide ranked by ideXlab platform
Malcolm A. Kelland - One of the best experts on this subject based on the ideXlab platform.
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An investigation into the laboratory method for the evaluation of the performance of kinetic hydrate inhibitors using Superheated Gas hydrates
Chemical Engineering Science, 2011Co-Authors: Luca Del Villano, Malcolm A. KellandAbstract:Abstract Kinetic hydrate inhibitors (KHIs) are used to prevent Gas hydrate formation in Gas and oilfield operations. Recently, a new KHI test method was reported in which hydrates are formed and re-melted just above the equilibrium temperature, before the fluids are re-cooled and the performance of the chemical as a KHI is determined. The method, which we have called the Superheated hydrate test method, is claimed to be more reliable for KHI ranking in small equipment, giving less scattering in the hold time data due to avoiding the stochastic nature of the first hydrate formation. We have independently investigated this Superheated hydrate test method in steel and sapphire autoclave tests using a Gas mixture forming Structure II hydrates and a liquid hydrocarbon phase, which was necessary for satisfactory results. Our results indicate that hold times are shorter than using non-Superheated hydrate test methods, but they are more reproducible with less scattering. The reduced scattering occurs in isothermal or slow ramping experiments even when the hydrates are melted at more than 10 °C above the equilibrium temperature ( T eq ). However, if a rapid cooling method is used, the improved reproducibility is retained when melting hydrate at 2.4 °C above T eq but lost when warming to 8.4 °C above T eq . Using the ramping test method, most, but not all the KHIs tested agreed with the same performance ranking obtained using traditional non-Superheated hydrate test methods. This may be related to the variation in the dissociation temperature of Gas hydrates with different KHIs and different KHI inhibition mechanisms. Results also varied between different size autoclave equipments.
Lei Wang - One of the best experts on this subject based on the ideXlab platform.
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Simulation on vertical wicking behaviors of liquid hydrogen within metallic weaves in terrestrial and microgravity environments
International Journal of Hydrogen Energy, 2020Co-Authors: Jianhua Ren, Lei WangAbstract:Abstract To predict the wicking performance of liquid hydrogen (LH2) in porous screens, we introduced an evaporative wicking model which has been verified by experiments in liquid nitrogen (LN2). The effects of the fluid properties, the gravity level, the Superheated degree and the screen structure parameters on the vertical wicking of saturated LH2 were systematically investigated. The wicking in LH2 performs better than that in LN2, presenting higher maximal wicking height and wicking velocity. At lower gravity, the wicking performance is better in whole but much more sensitive to the changes of Superheated condition and structure parameters of the screen. The thermal effect of Superheated Gas region plays a decisive role in wicking behaviors, significantly reducing the wicking velocity and equilibrium height. The effects of permeability and thickness of the screen are obviously different at Superheated condition compared to the isothermal cases.
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Investigation on interphase mixing and flow condensation process in a vertical channel
Experimental Thermal and Fluid Science, 2018Co-Authors: Kang Zhu, Jiaojiao Wang, Lei WangAbstract:Abstract In this paper, an experimental study is performed on the mixing of Superheated Gas and subcooled flowing liquid and the subsequent flow condensation process in a vertical visual flow channel using R123 as the working fluid. The flow patterns of the two phase flow in the vertical channel are verified and the flow condensation lengths of the Gaseous phase under different operating conditions are obtained. Test results indicate that under the operating conditions in this experiment, the Gaseous phase forms a cavity or a film at the Gas orifices, and then forms a dispersive bubbly flow in the downstream region. The flow condensation length of the Gaseous phase through a single orifice increases approximately linearly with the Gas flow rate over a range of 0.35–0.76 m, and it is reduced to a range of 0.27–0.56 m by using multiple Gas injection orifices. A computational fluid dynamics (CFD) model is established to simulate the two phase flow and interfacial heat and mass transfer in the channel. The simulation capability and prediction accuracy of the CFD model are validated by comparing numerical results of phase distributions as well as the flow condensation lengths with test data, and satisfying agreements are obtained. This work could be beneficial to the understanding and handling of interphase heat and mass transfer problems in in-tube two phase flows.
V. G. Baidakov - One of the best experts on this subject based on the ideXlab platform.
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Nucleation in Superheated Gas-saturated solutions. I. Boiling-up kinetics
The Journal of Chemical Physics, 1999Co-Authors: V. G. BaidakovAbstract:Nucleation in a Superheated Gas-saturated solution is regarded as a diffusional process in the space of three variables of a nucleus: Its volume υ and the partial pressures of the components p1″,p2″. The paper determines the surface relief of the thermodynamic potential in the vicinity of the saddle point and describes the growth of vapor bubbles in a solution with allowance for its viscosity, rate of evaporation of molecules of a solvent, and a dissolved substance, rate of diffusional supply of a substance to the bubble surface. The tensor of the generalized diffusion of nuclei, the decrement of increase of an unstable variable, the stationary nucleation rate have been calculated.
Wenxing Shi - One of the best experts on this subject based on the ideXlab platform.
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A new inverter heat pump operated all year round with domestic hot water
Energy Conversion and Management, 2004Co-Authors: Shuangquan Shao, Wenxing ShiAbstract:This paper presents a new scheme of an inverter air cooling heat pump system with domestic hot water. A water reheater is placed between the compressor outlet and the four way valve inlet to utilize the sensible heat of the Superheated Gas exhausted from the compressor, and a water preheater is placed between the condenser and the throttling device to use the sensible heat of the subcooled liquid flowing out of the condenser. With these two parts of heat, the domestic hot water can be heated to a temperature high enough for domestic use. In order to maintain the system efficiency in the period of part load, an inverter compressor is adopted as the substitute for the constant speed one used in the conventional heat pump system. A hot water storage tank with a circulation pump is placed in the system to reduce the peak load of the system. Compared with the traditional system, this new design is able to reduce energy consumption by 31.1% and decrease thermal pollution to the environment.
Luca Del Villano - One of the best experts on this subject based on the ideXlab platform.
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An investigation into the laboratory method for the evaluation of the performance of kinetic hydrate inhibitors using Superheated Gas hydrates
Chemical Engineering Science, 2011Co-Authors: Luca Del Villano, Malcolm A. KellandAbstract:Abstract Kinetic hydrate inhibitors (KHIs) are used to prevent Gas hydrate formation in Gas and oilfield operations. Recently, a new KHI test method was reported in which hydrates are formed and re-melted just above the equilibrium temperature, before the fluids are re-cooled and the performance of the chemical as a KHI is determined. The method, which we have called the Superheated hydrate test method, is claimed to be more reliable for KHI ranking in small equipment, giving less scattering in the hold time data due to avoiding the stochastic nature of the first hydrate formation. We have independently investigated this Superheated hydrate test method in steel and sapphire autoclave tests using a Gas mixture forming Structure II hydrates and a liquid hydrocarbon phase, which was necessary for satisfactory results. Our results indicate that hold times are shorter than using non-Superheated hydrate test methods, but they are more reproducible with less scattering. The reduced scattering occurs in isothermal or slow ramping experiments even when the hydrates are melted at more than 10 °C above the equilibrium temperature ( T eq ). However, if a rapid cooling method is used, the improved reproducibility is retained when melting hydrate at 2.4 °C above T eq but lost when warming to 8.4 °C above T eq . Using the ramping test method, most, but not all the KHIs tested agreed with the same performance ranking obtained using traditional non-Superheated hydrate test methods. This may be related to the variation in the dissociation temperature of Gas hydrates with different KHIs and different KHI inhibition mechanisms. Results also varied between different size autoclave equipments.