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energy-efficient methods for production methane from natural gas hydrates

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Journal of energy Chemistry 2015年第5期24卷 552-558页

作者： Jun Chen Yan-Hong Wang Xue-Mei Lang Shuan-Shi Fan key lab of enhanced heat transfer and energy conservation Ministry of Education South China University of Technology

Gas hydrates now are expected to be one of the most important future unconventional energy resources. In this paper, researches on gas hydrate exploitation in laboratory and field were reviewed and discussed from the aspects of energy efficiency. Different exploiting methods and different types of hydrate reservoir were selected to study their effects on energy efficiencies. Both laboratory studies and field tests have shown that the improved technologies can help to increase efficiency for gas hydrate exploitation. And it also showed the trend that gas hydrate exploitation started to change from permafrost to marine. energy efficiency ratio （EER） and energy return on energy invested （EROI） were introduced as an indicator of efficiency for natural gas hydrate exploitation. An energy-efficient hydrate production process, called ＂Hydrate Chain energy System （HCES）＂, including treatment of flue gas, replacement of CH4 with CO2, separation of CO2 from CH4, and storage and transportation of CH4 in hydrate form, was proposed for future natural gas hydrate exploitation. In the meanwhile, some problems, such as mechanism of C02 replacement, mechanism of CO2 separation, CH4 storage and transportation are also needed to be solved for increasing the energy efficiency of gas hydrate exploitation.

关键词： Gas hydrates Exploitation energy efficiency EROI Strategy

Experimental and Numerical Study on heat transfer Enhancement of a Rectangular Channel with Discontinuous Crossed Ribs and Grooves

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chinese Journal of Chemical Engineering 2012年第2期20卷 220-230页

作者：唐新宜朱冬生 key laboratory of enhanced heat transfer and energy conservation of the ministry of education South China University of Technology

Experimental and numerical investigations have been conducted to study turbulent flow of water and heat transfer characteristics in a rectangular channel with discontinuous crossed ribs and *** tests investigated the overall heat transfer performance and friction factor in ribbed and ribbed-grooved channels with rib angle of 30°.The experimental results show that the overall thermo-hydraulic performance for ribbed-grooved channel is increased by 10%-13.6% when compared to ribbed *** investigation on the effects of different rib angles and rib pitches on heat transfer characteristics and friction factor in ribbed-grooved channel was carried out using Fluent with SST(shear-stress transport) k-ω turbulence *** numerical results indicate that the case for rib angle of 45° shows the best overall thermo-hydraulic performance,about 18%-36% higher than the case for rib angle of 0°.In addition,the flow patterns and local heat transfer characteristics for ribbed and ribbed-grooved channels based on the numerical simulation were also analyzed to reveal the mechanism of heat transfer enhancement.

关键词： heat transfer enhancement rib groove rectangular channel turbulent flow

Constructs of highly effective heat transport paths by bionic optimization

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Science China(Technological Sciences) 2003年第3期46卷 296-302页

作者：程新广李志信过增元 Department of Engineering Mechanics Key Lab of Enhanced Heat Transfer and Energy Conservation of Education MinistryTsinghua University

The optimization approach based on the biological evolution principle is used to con-struct the heat transport paths for volume-to-point problem. The transport paths are constructed by inserting high conductivity materials in the heat conduction domain where uniform or nonuniform heat sources exist. In the bionic optimization process, the optimal constructs of the high conductiv-ity material are obtained by numerically simulating the evolution and degeneration process ac-cording to the uniformity principle of the temperature gradient. Finally, preserving the features of the optimal constructs, the constructs are regularized for the convenience of engineering manu-facture. The results show that the construct obtained by bionic optimization is approximate to that obtained by the tree-network constructal theory when the heat conduction is enhanced for the do-main with a uniform heat source and high conductivity ratio of the inserting material to the sub-strate, the high conductivity materials are mainly concentrated on the heat outlet for the case with a uniform heat source and low thermal conductivity ratio, and for the case with nonuniform heat sources, the high conductivity material is concentrated in the heat source regions and construacts several highly effective heat transport paths to connect the regions to the outlet.

关键词： bionic optimization approach, heat conduction optimization, constructs of high conductivity material.

Hydrate capture CO_2 from shifted synthesis gas, flue gas and sour natural gas or biogas

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Journal of energy Chemistry 2013年第1期22卷 39-47页

作者： Yanhong Wang Xuemei Lang Shuanshi Fan School of Chemistry and Chemical Engineering Key Lab of Enhanced Heat Transfer and Energy Conservation Ministry of Education South China University of Technology

CO2 capture by hydrate formation is a novel gas separation technology, by which CO2 is selectively engaged in the cages of hydrate and is separated with other gases, based on the differences of phase equilibrium for CO2 and other gases. However. rigorous temperature and pressure, high energy cost and industrialized hydration separator dragged the development of the hydrate based CO2 capture. In this paper, the key problems in CO2 capture from the different sources such as shifted synthesis gas, flue gas and sour natural gas or biogas were analyzed. For shifted synthesis gas and flue gas, its high energy consumption is the barrier, and for the sour natural gas or biogas （CO2/CH4 system）, the bottleneck is how to enhance the selectivity of CO2 hydration. For these gases, scale-up is the main difficulty. Also, this paper explored the possibility of separating different gases by selective hydrate formation and reviewed the progress of CO2 separation from shifted synthesis gas, flue gas and sour natural gas or biogas.

关键词： clathrate hydrate: C02 capture hydrogen shifted synthesis gas flue gas sour natural gas or biogas

Evidence for pore-filling gas hydrates in the sediments through morphology observation

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chinese Journal of Chemical Engineering 2019年第9期27卷 2081-2088页

作者： Wenxiang Zhang Shuanshi Fan Yanhong Wang Xuemei Lang Kai Guo Jianbiao Chen key lab of enhanced heat transfer and energy conservation ministry of education School of Chemistry and Chemical Engineering South China University of Technology

To provide an evidence of natural gas hydrate occurrence state,a series of experiments on multiple growth and dissociation of 90.0%methane/10.0%propane hydrates at 1.3 MPa and 270.15 K were carried out in two sediments for morphology observation via a visible *** gas hydrate crystals were observed to form and grow on the surface of sediments at the initial *** the thermal decomposition,gas and liquid products had an unceasingly impact on the sediments,then gas/liquid–solid migration occurred,and a large number of cavitation *** the later growth and dissociation experiments,the gas hydrate particles were in suspension or supporting states in the interstitial pore space between the sediment particles,indicating that the gas hydrate displayed a pore-filling *** analyzing the distribution of gas hydrates and bubbles,it was found that the amount of gas hydrates distributed in the sediments was improved with multiple growth-dissociation cycle *** migration enhanced the sediment movement,which led to the appearance of the increasing quantity of gas bubbles in the sediments during *** affected the growth of the gas hydrates and the migration of sediment grains,which also restricted the accumulation of gas bubbles in the *** to the Raman analysis,the results showed that sII hydrates were formed for CH4 and C3H8 gas mixtures in different sediments and solutions with hydration number of 5.84–*** Salt restricted the access of gas into the hydrate cages.

关键词： Gas hydrate Sediments Growth Dissociation Pore-filling

3D Numerical Study on Compound heat transfer Enhancement of Converging-diverging Tubes Equipped with Twin Twisted Tapes

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chinese Journal of Chemical Engineering 2012年第3期20卷 589-601页

作者：洪宇翔邓先和张连山 key lab of enhanced heat transfer and energy conservation of ministry of education School of Chemistry and Chemical EngineeringSouth China University of Technology

The paper presents a 3D numerical simulation of turbulent heat transfer and flow characteristics in converging-diverging tubes （CDs） and converging-diverg）ng *** with twin counter-swirling twisted tapes （CDTs）. The effects of Reynolds number （Re= 10000-20000）, pitch length （P= 11.25, 22.5 mm）, rib height （e = 0.5, 0.8, 1.1 ram）, pitch ratio （8= 1 ＂ 8, 5 ＂ 4, 8 ＂ 1）, gap distance between twin t）visted tapes （b = 0.5, 4.5, 8.5 mm） and tape number （n = 2, 3, 4, 5, 6） on Nusselt number （Nu）, Iriction tactor 0＇） and thermal enhancement factor （r/） are investigated under uniform heat flux conditions,using water as working fluid. In order to illustrate the heat transter and tlu^d tlow mechamsms, flow structures m ~StJs and ~SDIs are presented. The obtained results reveal that all geometric parameters have important effects on the thermal performance of CD and CDT, and both CD and CDT show better thermal performance than plain tube at the constant pumping power. It is also found that the increases in the Nusselt number and friction factor for CDT are, respectively, up to 6.3%-35.7% and 1.75-5.3 times of thecorresponding bare CD. All CDTs have good thermal perbrmance with greater than 1 which indicates that the compound heat transfer technique of CDT is commendable for the maximum enhanced heat transfer rate.

关键词： heat transfer enhancement converging-diverging tube twisted tape numerical simulation

Design,fabrication and experimental research for an electrohydrodynamic micropump

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Science China(Technological Sciences) 2010年第10期53卷 2839-2845页

作者： YU He, YU Jian & MA ChongFang key lab of enhanced heat transfer & energy conservation, ministry of education and key lab of heat transfer & energy Conversion, Beijing Municipality, College of Enviromental and energy Engineering, Beijing University of Technology, Beijing 100124, China key lab of enhanced heat transfer & energy conservation Ministry of Education and Key Lab of Heat Transfer & Energy Conversion Beijing Municipality College of Enviromental and Energy Engineering Beijing University of Technology

This paper presented a novel electrohydrodynamic (EHD) micropump based on MEMS technology. The working mechanisms and classification of EHD micropump were introduced. The fabrication process of EHD micropump was presented with the material selection,optimal design of microelectrode and assembly process. Static pressure experiments and flow experiments were carried out using different fluid and the channel depth. The results indicated that the micropump could achieve a maximum static pressure head of 268 Pa at an applied voltage of 90 V. The maximum flow rate of the micropump-driven fluid could reach 106 μL/min. This paper analyzed the future of combining micropump with heat pipe to deal with heat dissipation of high power electronic chips. The maximum heat dissipation capacity of 87 W/cm2 can be realized by vaporizing the micropump-driven liquid on vaporizing section of the heat pipe.

关键词： electrohydrodynamic (EHD) MEMS micropump electronic cooling

Reviews of gas hydrate inhibitors in gas-dominant pipelines and application of kinetic hydrate inhibitors in China

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chinese Journal of Chemical Engineering 2019年第9期27卷 2118-2132页

作者： Yanhong Wang Shuanshi Fan Xuemei Lang key lab of enhanced heat transfer and energy conservation Ministry Education School of Chemistry and Chemical Engineering South China University of Technology

During the development and application of natural gas,hydrate plugging the pipelines is a very important issue to ***,adding thermodynamic hydrate inhibitors(THIs)and kinetic hydrate inhibitors(KHIs)in gas-dominated pipelines is a main way to prevent hydrate plugging of flow *** paper mainly reviews the efforts to develop THIs and KHIs in the past 20 years,compare the role of various THIs,such as methanol,ethylene glycol and electrolyte,and give the tips in *** direction of KHIs is toward high efficiency,low toxicity,low pollution and low *** than a hundred inhibitors,including polymers,natural products and ionic liquids,have been synthesized in the past *** of them have better performance than the current commercial ***,there are still few problems,such as the complex synthesis process,high cost and low solubility,impeding the commercialization of these *** review also summarized some application of KHIs in *** of KHIs in China began *** are no KHIs used in gas *** a few field tests have been carried *** the end of this paper,the field test of self-developed KHIs by China is summarized,and the guidance is given according to the application results.

关键词： Gas hydrate Thermal hydrate inhibitor Kinetic hydrate inhibitor Dual-effect inhibitor Field testing

Experimental Study on Emission Control of Premixed Catalytic Combustion of Natural Gas Using Preheated Air

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chinese Journal of Chemical Engineering 2007年第1期15卷 68-74页

作者：许考刘中良何洪程水源马重芳 key laboratory of enhanced heat transfer and energy conservation Ministry of Education and Key Laboratory of Heat Transfer and Energy Conversion College of Environmental & Energy Engineering Beijing University of Technology Beijing 100022 China

In this paper the premixed catalytic combustion emissions such as CO, unburned hydrocarbon (UHC), NOx and the temperature distribution in the catalytic monolith with ultra low concentration of Pd were studied. Three types of monoliths were used for experiments and the temperature of preheated air was respectively 50℃ , 100℃ and 200℃ . The results showed that preheated air made radial temperature in the catalytic monolith uniform which helped to avoid local hot spots so as to decrease NOx emission. The experiment also proved that the shorter monolith showed much better catalytic combustion performance than longer one and the temperature at the exit of the shorter monolith was relatively lower. On the contrary, the temperature was higher in the longer monolith and the lethal NOx emission was slightly increased.

关键词： catalytic combustion preheated air natural gas emission