查看更多>>摘要：The spiral-wound heat exchanger(SWHE)is the primary low-temperature heat exchanger for large-scale LNG plants due to its high-pressure resistance,compact structure,and high heat exchange efficiency.This paper studied the shell-side heat and mass transfer characteristics of vapor-liquid two-phase mixed refrigerants in an SWHE by combining a multi-component model in FLUENT software with a customized multicomponent mass transfer model.Besides,the mathematical model under the sloshing condition was obtained through mathematical derivation,and the corresponding UDF code was loaded into FLUENT as the momentum source term.The results under the sloshing conditions were compared with the relevant parameters under the steady-state condition.The shell-side heat and mass transfer char-acteristics of the SWHE were investigated by adjusting the component ratio and other working condi-tions.It was found that the sloshing conditions enhance the heat transfer performance and sometimes have insignificant effects.The sloshing condition is beneficial to reduce the flow resistance.The comprehensive performance of multi-component refrigerants has been improved and the improvement is more significant under sloshing conditions,considering both the heat transfer and pressure drop.These results will provide theoretical support for the research and design of multi-component heat and mass transfer enhancement of LNG SWHE under ocean sloshing conditions.
查看更多>>摘要：This contribution presents a novel wear dependent virtual flow rate sensor for single stage single lobe progressing cavity pumps.We study the wear-induced material loss of the pump components and the impact of this material loss on the volumetric efficiency.The results are combined with an established backflow model to implement a backflow calculation procedure that is adaptive to wear.We use a laboratory test setup with a highly abrasive fluid and operate a pump from new to worn condition to validate our approach.The obtained measurement data show that the presented virtual sensor is capable of calculating the flow rate of a pump being subject to wear during its regular operation.
查看更多>>摘要：The electric submersible pump(ESP)is a crucial apparatus utilized for lifting in the oil extraction process.Its lifting capacity is enhanced by the multi-stage tandem structure,but variations in energy charac-teristics and internal flow across stages are also introduced.In this study,the inter-stage variability of energy characteristics in ESP hydraulic systems is investigated through entropy production(EP)analysis,which incorporates numerical simulations and experimental validation.The EP theory facilitates the quantification of energy loss in each computational subdomain at all ESP stages,establishing a corre-lation between microscopic flow structure and energy dissipation within the system.Furthermore,the underlying causes of inter-stage variability in ESP hydraulic systems are examined,and the advantages and disadvantages of applying the EP theory in this context are evaluated.Consistent energy charac-teristics within the ESP,aligned with the distribution of internal flow structure,are provided by the EP theory,as demonstrated by our results.The EP theory also enables the quantitative analysis of internal flow losses and complements existing performance analysis methods to map the internal flow structure to hydraulic losses.Nonetheless,an inconsistency between the energy characterization based on EP theory and the traditional efficiency index when reflecting inter-stage differences is identified.This inconsistency arises from the exclusive focus of the EP theory on flow losses within the flow field,dis-regarding the quantification of external energy input to the flow field.This study provides a reference for the optimization of EP theory in rotating machinery while deeply investigating the energy dissipation characteristics of multistage hydraulic system,which has certain theoretical and practical significance.
查看更多>>摘要：Liquid hydrogen storage and transportation is an effective method for large-scale transportation and utilization of hydrogen energy.Revealing the flow mechanism of cryogenic working fluid is the key to optimize heat exchanger structure and hydrogen liquefaction process(LH2).The methods of cryogenic visualization experiment,theoretical analysis and numerical simulation are conducted to study the falling film flow characteristics with the effect of co-current gas flow in LH2 spiral wound heat exchanger.The results show that the flow rate of mixed refrigerant has a great influence on liquid film spreading process,falling film flow pattern and heat transfer performance.The liquid film of LH2 mixed refrigerant with column flow pattern can not uniformly and completely cover the tube wall surface.As liquid flow rate increases,the falling film flow pattern evolves into sheet-column flow and sheet flow,and liquid film completely covers the surface of tube wall.With the increase of shear effect of gas-phase mixed refrigerant in the same direction,the liquid film gradually becomes unstable,and the flow pattern eventually evolves into a mist flow.
Li WangChen-Hao GaoRui-Ying XiongXiao-Jun Zhang...
1385-1395页
查看更多>>摘要：As an unconventional resource,oil shale possesses abundant reserves and significant potential for in-dustrial applications.The rational and efficient development of oil shale resources holds immense importance in reducing national energy demand.In-situ catalytic technology,characterized by its high efficiency,low pollution,and minimal energy consumption,represents a key direction for future oil shale development.This paper provides a comprehensive review of research progress in in-situ oil shale mining technology,oil shale pyrolysis catalysts,the pyrolysis mechanism of kerogen,and the compati-bility of different heating processes and catalysts.Furthermore,the paper proposes future research di-rections and prospects for oil shale in-situ catalytic technology,including reservoir modification,high-efficiency catalyst synthesis,injection processes,and high-efficiency heating technology.These in-sights serve as valuable technical references for the advancement of oil shale in-situ catalytic technology.
查看更多>>摘要：The natural gas hydrate has become one of the most promising future green energy sources on the earth.The natural gas hydrates mostly exist in the sediments with porous structure,so a solid understanding of the hydrate formation and growth processes in the porous medium is of significance for the exploitation of natural gas hydrate.The micro-packed bed device is one of the efficient microfluidic devices in the engineering field,but it has been rarely used for the hydrate-based research.In this study,a transparent micro-packed bed device filled with glass beads was developed to mimic the porous condition of sed-iments,and used to in-situ visualize the hydrate formation and growth habits in the pore spaces under both static and dynamic conditions.For the static experiment,two types of hydrate growth patterns in porous medium were observed and identified in the micro-packed bed device,which were the grain-coating growth and pore-filling growth.For the dynamic condition,the hydrate formation,growth,distribution habits and hydrate blockage phenomena in the pore spaces were in-situ visually captured.The impacts of flowrate and subcooling on the pressure variation of the micro-packed bed and the duration of the hydrate growth under dynamic flow condition in pores were in-situ monitored and analyzed.The higher flowrate could result in the faster hydrate growth and more severe blockage in pores,but the effect of subcooling condition might be less significant at the high flowrate.
查看更多>>摘要：A series of model catalysts were obtained by treating commercial fresh and spent catalysts unloaded from the factory with different methods,including green oil dipping,extraction and high-temperature regeneration;finally,the deactivation behavior of the commercial catalyst for acetylene hydrogenation were studied.The influence of various possible deactivation factors on the catalytic performance was elucidated via detailed structural characterization,surface composition analysis,and activity evaluation.The results showed that green oil,carbon deposit and sintering of active metal were the main reasons for deactivation,among which green oil and carbon deposit led to rapid deactivation,while the activity could be recovered after regeneration by high-temperature calcination.The sintering of active metal components was attributed to the high-temperature regeneration in hydrothermal conditions,which was slow but irreversible and accounted for permanent deactivation.Thus,optimizing the regeneration is expected to extend the service life of the commercial catalyst.
查看更多>>摘要：This paper attempts to explore the decoupling relationship and its drivers between industrial economic increase and energy-related CO2 emissions(ICE).Firstly,the decoupling relationship was evaluated by Tapio index.Then,based on the DEA meta-frontier theory framework which taking into account the regional and industrial heterogeneity and index decomposition method,the driving factors of decoupling process were explored mainly from the view of technology and efficiency.The results show that during 2000-2019,weak decoupling was the primary state.Investment scale expansion was the largest reason hindering decoupling process of industrial increase from ICE.Both energy saving and production tech-nology achieved significant progress,which facilitated the decoupling process.Simultaneously,the en-ergy technology gap and production technology gap among regions have been narrowed,and played a role in promoting decoupling process.On the contrary,both scale economy efficiency and pure technical efficiency have inhibiting effects on decoupling process.The former indicates that the scale economy of China's industry was not conducive to improve energy efficiency and production efficiency,while the latter indicates that resource misallocation problem may exist in both energy market and product market.
查看更多>>摘要：With the implementation of the Belt and Road Initiative,China is deepening its cooperation in oil and gas resources with countries along the Initiative.In order to better mitigate risks and enhance the safety of investments,it is of significant importance to research the oil and gas investment environment in these countries for China's overseas investment macro-layout.This paper proposes an indicator system including 27 indicators from 6 dimensions.On this basis,game theory models combined with global entropy method and analytic hierarchy process are applied to determine the combined weights,and the TOPSIS-GRA model is utilized to assess the risks of oil and gas investment in 76 countries along the Initiative from 2014 to 2021.Finally,the GM(1,1)model is employed to predict risk values for 2022-2025.In conclusion,oil and gas resources and political factors have the greatest impact on investment environment risk,and 12 countries with greater investment potential are selected through cluster analysis in conjunction with the predicted results.The research findings may provide scientific decision-making recommendations for the Chinese government and oil enterprises to strengthen oil and gas investment cooperation with countries along the Belt and Road Initiative.
查看更多>>摘要：This study examines the systemic risk caused by major events in the international energy market(IEM)and proposes a management strategy to mitigate it.Using the tail-event driven network(TENET)method,this study constructed a tail-risk spillover network(TRSN)of IEM and simulated the dynamic spillover tail-risk process through the cascading failure mechanism.The study found that renewable energy markets contributed more to systemic risk during the Paris Agreement and the COVID-19 pandemic,while fossil energy markets played a larger role during the Russia-Ukraine conflict.This study identifies systemically important markets(SM)and critical tail-risk spillover paths as potential sources of systemic risk.The research confirms that cutting off the IEM risk spillover path can greatly reduce systemic risk and the influence of SM.This study offers insights into the management of systemic risk in IEM and provides policy recommendations to reduce the impact of shock events.
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