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Numerical study on shell-side shear flow and heat transfer in a spiral wound heat exchanger under onshore/offshore conditions

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APPLIED THERMAL engineering 2025年 267卷

作者： Ren, Yan Guo, Yixin Cai, Weihua Jiang, Yiqiang Wu, Weidong Yang, Yingying Chen, Jie Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai Peoples R China Norhteast Elect Power Univ Sch Energy & Power Engn Jilin Peoples R China Harbin Inst Technol Dept Bldg Thermal Energy Engn Harbin Peoples R China CNOOC Gas & Power Grp Beijing Peoples R China

Given that studies on shell-side shear flow and heat transfer characteristics in spiral wound heat exchangers (SWHEs) used in floating liquefied natural gas (FLNG) systems are still scarce, a mathematical-physical model was established based on the two-fluid thermal phase change model, incorporating a modified mean diameter of the dispersed phase. According to the results under onshore conditions with operating pressure ranging from 0.2 to 0.6 MPa, mass flux ranging from 40 to 100 kg/(m2 & sdot;s), heat flux ranging from 2,000 to 8,000 W/m2, and vapor quality ranging from 0.3 to 0.9, respectively, the shell-side frictional pressure drop gradient increased with decreasing operating pressure and increasing mass flux and vapor quality. The effect of the heat flux was negligible and could be ignored. The offshore conditions significantly increased the proportion of shear flow on the SWHE shell side. Therefore, the effects of the rolling and operating parameters on the shear flow were investigated with rolling amplitudes and periods of 5-15 degrees and 5-15 s, respectively. Consequently, the flow and heat transfer characteristics of the shell-side shear flow exhibited sinusoidal periodic fluctuations owing to the influence of the rolling motion, and their fluctuation periods were approximately equal to the rolling period. Within the allowable operating range, a higher mass flux could not only effectively resist the influence of the rolling motion but also maintain the heat exchanger performance at a higher level while delaying the adverse drying of the heat exchange tube wall. Additionally, Aunan's correlation was proven to exhibit good adaptability for calculating the frictional pressure drop gradient of shear flow under both onshore and offshore conditions. These results provide guidance for the design and operation of FLNG SWHEs.

关键词： Shear flow Thermal phase change model flow and heat transfer Shell side FLNG

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Insights into Co and Fe-doping effects of mesoporous CeO2 catalysts for dry reforming of glycerol to syngas production

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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY 2024年 67卷 970-978页

作者： Wang, Yadong Dou, Binlin Zhang, Hua Ren, Ruijia Wu, Kai Li, Wei Chen, Haisheng Xu, Yujie Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China Zhejiang Univ Dept Energy Engn Hangzhou 310027 Peoples R China Chinese Acad Sci Inst Engn Thermophys Beijing 100190 Peoples R China

The dry reforming of glycerol (GDR) is one of the alternatives for syngas production by utilizing biodiesel byproduct glycerol and CO2. The development of highly active and stable catalyst is significantly important to achieve GDR process, and the current work provides insights into Co and Fe-doping effects of mesoporous CeO2 (CoFeCe) catalysts synthesized by the colloidal solution combustion method. The prepared catalysts presented the uniform mesoporous structure, the doping of Co and Fe metals resulted in stronger metal-support interaction. The GDR experimental data were compared with the non-stoichiometric thermodynamic equilibrium values. The conversions of glycerol and CO2 were increased with increasing the reaction temperatures due to the endothermic GDR reaction, and the H2/CO produced in syngas was in the range of 0.7-1.4. Due to the improvement of Co and Fe metals in the mesoporous structure of CeO2 catalyst, the 7CoFeCe catalyst exhibited excellent and stable GDR performance and no significant signs of deactivation were observed during 76 h test, and the results indicated that the enhanced interaction and high dispersion of Co and Fe in mesoporous CeO2 catalyst could inhibit carbon formation and promote GDR reaction.

关键词： Dry reforming of glycerol (GDR) CO 2 utilization Mesoporous CoFeCe catalyst Syngas production

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Optimization of Thermal Conductivity of Alumina-Filled Composites by Numerical Simulations

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Journal of Thermal Science 2023年第4期32卷 1569-1582页

作者： LI Shikun LIU Bin JIA Xiao XU Min ZONG Ruoyu LIU Guohua HUAI Xiulan Beijing Key Laboratory of Multiphase Flow and Heat Transfer for Low Grade Energy Utilization North China Electric Power UniversityBeijing102206China Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing100190China Nanjing Institute of Future Energy System Nanjing211135China

Understanding the correlation between the physical features of composite components and thermal conductive pathway is beneficial to optimizing the overall heat-transfer ***,we conduct numerical simulation to investigate the thermal conductivity and heat flux distributions of alumina(Al_(2)O_(3))-filled *** finite element model was verified by both experimental data and theoretical *** crucial factors include the influence of the interface thermal resistance,the intrinsic thermal conductivity of the matrix and Al_(2)O_(3)filler,and the size effect of Al_(2)O_(3)fillers were *** single Al_(2)O_(3)-filled composites,the results indicate that increasing the intrinsic thermal conductivity of the matrix is conductive to bridge the Al_(2)O_(3)pathway along heat-transfer direction,but there are very limited contributions by enhancing the intrinsic thermal conductivity of Al_(2)O_(3)filler,tuning the size of Al_(2)O_(3)filler,and reducing the interface thermal *** introducing the multiscale fillers,it is found that the high thermal conductivity can be achieved by regulating their size matching *** the optimal binary ratio of 70:30(40µm:15µm)and ternary ratio of 55:35:10(40µm:15µm:10µm),the heat-conduction network presents the dominant skeleton of large-sized filler and the bridging branch of small-sized fillers features,which facilitates the formation of a complete and continuous thermal conductive *** study gives a practical guidance for the thermal conductive design of Al_(2)O_(3)-filled composites.

关键词： optimization size matching effect thermal conductivity numerical simulation multiscale Al_(2)O_(3)filler

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Chemical looping dry reforming of waste glycerol coupled with thermochemical water splitting cycle by mesoporous Fe2O3-Co3O4/CeO2 oxygen carriers

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CHEMICAL engineering JOURNAL 2024年 493卷

作者： Wu, Kai Dou, Binlin Zhang, Hua Wang, Yadong Chen, Haisheng Xu, Yujie Li, Wei Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China Chinese Acad Sci Inst Engn Thermophys Beijing 100190 Peoples R China Zhejiang Univ Dept Energy Engn Hangzhou 310027 Peoples R China

A coupled chemical looping conversion of glycerol and CO 2 with thermochemical water splitting (WS) cycle is substantially researched due to its potential for one-step renewable H 2 and syngas production. The major challenge lies on having good controls of redox reactions of the oxygen carriers (OCs) used and its unusual sensitivity to the changes of the compositions, chemical states and structure, etc. Here, we develop the OCs that consists of Fe 2 O 3 -Co 3 O 4 supported on the mesoporous CeO 2 structure (Fe 2 O 3 -Co 3 O 4 /CeO 2 ), which simultaneously promote glycerol oxidization (GO), dry reforming of glycerol (GDR), and WS processes. The easy migration and activation of lattice oxygen by Fe 2 O 3 -Co 3 O 4 /CeO 2 greatly improved the GO and GDR to produce syngas at the first step, and the pure H 2 production by the reduced Fe 2 O 3 -Co 3 O 4 /CeO 2 achieved excellent WS and oxygen storage at 750 degree celsius. The low -content Fe dopant in the OC presented a beneficial effect on the anti -sintering performance, and increase of Co -doping indicated a high activity to WS as well as enhanced GDR. The Fe 2 O 3 - Co 3 O 4 /CeO 2 with 7:5:10 of Co: Fe: Ce molar ratio presented the highest glycerol and CO 2 conversions and the highest H 2 yield, also illustrated the excellent activity and stability in 40 consecutive redox cycles.

关键词： Chemical looping conversion of glycerol and CO2 Glycerol oxidization (GO) Glycerol dry reforming (GDR) Water splitting (WS) Oxygen carriers (OCs)

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Experimental investigation on the flow boiling of R134a in a plate heat exchanger with mini-wavy corrugations

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INTERNATIONAL JOURNAL OF REFRIGERATION 2024年 162卷 53-63页

作者： Lao, Wei-chao Fang, Yi-dong Chen, Qing-hu Xu, Lin-jie Yang, Hui-nan Huang, Yu-qi Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China Yinlun Co Ltd Taizhou 317200 Peoples R China Zhejiang Univ Qingshanhu Energy Res Ctr Hangzhou 310027 Peoples R China

As a common component in various applications, the two-phase heat transfer of plate heat exchanger has been frequently studied. However, further investigations are still required on the flow pattern, especially for those with new plate structures brought with the emergence of new applications. This study presented an experimental investigation on the flow boiling of R134a in a plate heat exchanger with mini -wavy corrugations designed for thermal management system of electric vehicle (EV). The flow pattern transitions in the test section were captured and discussed, meanwhile the effects of vapor quality and mass flux on the variation of heat transfer coefficient (HTC) were analyzed. Based on the observation, the two-phase flow pattern developed from pulsating film flow, then rough stream flow and finally to thin stream flow with the increase of vapor quality. The flow pattern map was determined with the superficial momentum of the liquid and vapor phase refrigerant, while the empirical correlations were developed based on two-phase Weber number to predict the transitions between the flow patterns. The HTC showed an intermediate increase firstly under low vapor qualities, and rapidly decreased after reaching the peak value at the vapor quality of 0.45 - 0.6. In addition, the experimental data were compared with the present correlations, and a new Nu correlation was developed considering the transitions of flow patterns, showing an optimal prediction on the experimental data with the mean absolute error of 11.3%.

关键词： flow boiling Plate heat exchanger Wavy-corrugation flow pattern heat transfer

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A study on three coalescence modes of non-collinear parallel elliptical double cracks

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INTERNATIONAL JOURNAL OF PRESSURE VESSELS AND PIPING 2024年 210卷

作者： Liu, Hongxia Wang, Xiaoxiao Liu, Fang Cui, Wei Yang, Jie Chen, Haofeng Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China East China Univ Sci & Technol Key Lab Pressure Syst & Safety Minist Educ Shanghai 200237 Peoples R China Univ Shanghai Sci & Technol Sch Mech Engn Shanghai 200093 Peoples R China

Based on the Gurson-Tvergaard-Needleman (GTN) damage model, this study focused on the coalescence modes of non-collinear parallel elliptical double cracks in a homogeneous plate, and the coalescence modes of elliptical double cracks under different horizontal distances and vertical distances were investigated. The ratio of horizontal distance s to crack length a was taken as the horizontal axis, the ratio of vertical distance h to crack length a was taken as the vertical axis to plot the graph, then the coalescence modes were summarized and compared with the coalescence modes of linear double cracks. It was found that the non-collinear parallel elliptical double cracks exhibited three coalescence modes: crack tip to crack tip coalescing, crack interval to crack interval coalescing, and crack tip to crack interval coalescing. Each coalescence mode had its own characteristics. The three coalescence modes were distributed regularly in three regions in the graph with s/a and h/a as coordinates. When the horizontal distance s and the vertical distance h between the double cracks were equal respectively, there were significant differences in the crack propagation process and coalescence modes between elliptical double cracks and linear double cracks.

关键词： Elliptical double cracks Coalescence modes Coalescence law GTN damage model

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heat transfer Enhancement of Partially Serrated Twisted Finned Tube Bank

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heat transfer engineering 2023年第21-22期44卷 2079-2090页

作者： Wei, Hongyu Cong, Tao Jiang, Chen Zhou, Wenxue Bai, Bofeng Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian Peoples R China Shanghai Lanbin Petrochem Equipment Co Ltd Shanghai Peoples R China Lanzhou Heat Transfer & Energy Saving Engn & Techn Lanzhou Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China

Due to the large thermal resistance on the airside of the air-cooled heat exchangers, it is necessary to improve heat transfer performance and reduce flow resistance by improving the fin structure. In this paper, partially serrated finned tube bank was proposed and numerically investigated. The experimental system of finned tube bank was built to verify the correctness of the numerical simulation. The finned tube bank is twisted and serrated on the windward side to enhance heat transfer. Moreover, the non-grooved sector region on the leeward side reduces the flow resistance and improves the temperature uniformity of the fins. The effects of fin twisting of the windward side and non-grooving angle of the leeward side were explored. Nusselt number and friction factor decrease as the leeward non-grooving sector region increases. The correlations of Nusselt number and friction factor were derived based on the simulation results of partially serrated twisted finned tube banks with 120 degrees non-grooving region on the leeward side. Nusselt number, friction factor and comprehensive heat transfer coefficient of partially serrated twisted finned tube bank are 13.3%, 13.0% and 10.5% higher than that of annular finned tube bank with Reynolds number from 6200 to 20,600, respectively.

关键词： Nusselt number

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Interaction between Neighboring Supercritical Water Molecules and Density Fluctuation by Molecular Dynamics Simulations

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Journal of Thermal Science 2022年第3期31卷 907-922页

作者： WANG Yan XU Jinliang MA Xiaojing Key Laboratory of Condition Monitoring and Control for Power Plant Equipment of Ministry of Education North China Electric Power UniversityBeijing102206China Beijing Key Laboratory of Multiphase Flow and Heat Transfer North China Electric Power UniversityBeijing102206China

Supercritical water(scW)is important for various engineering *** structure and distribution of sc W is key to dominate the related processes and ***,scW is investigated using molecular dynamics(MD)simulation with controlled pressure and *** oscillation is observed to occur in a 1 nm thickness bin,indicating mass exchange of particles across the bin *** show that the low density scW behaves strong *** analysis of system density fluctuations is performed by square root error and maximum structure factor,demonstrating the agreement between the two *** scW molecules are tightly gathered to form“liquid island”locally,but are very sparse in other regions,which are similar to the gas-liquid mixture in subcritical pressure.A target molecule is tracked to plot 3D displacements and rotating angles,with the former indicating large amplitude ballistic(diffusing)motion and small amplitude oscillation,and the latter displaying two scales of angle *** translation and rotating motion are related to hydrogen bond break up and *** low density scW behaves isolated molecules with few combinations of hydrogen bonds between molecules,while the high density scW behaves more combinations of molecules via hydrogen *** two scales motion is expected to influence thermal/chemical process in supercritical state,deepening the fundamental understanding of scW structure.

关键词： supercritical water molecular dynamics density hydrogen bond translation and rotating motion

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Study on the leakage in water-injected twin-screw steam compressor

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PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART E-JOURNAL OF PROCESS MECHANICAL engineering 2023年第6期237卷 2244-2256页

作者： Tian, Yafen Yuan, Hao Geng, Yanting Zhao, Zhaorui Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Univ Shanghai Sci & Technol Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai Peoples R China Shanghai Marine Diesel Engine Res Inst Dept Compressor Shanghai Peoples R China

Steam compressor shows great energy-saving potential in mechanical vapor compression and high-temperature heat pump systems. However, leakage remains a huge problem for compressor performance improvement and design optimization. In this article, a thermodynamic model with detailed leakage flow model was developed for the working process in water-injected twin-screw compressor. Altogether, leakage in different paths and heat and mass transfer between injected liquid and compressed vapor were considered. Compared with experimental results, the accuracy of predicted efficiency is within +/- 5% for all tested operating conditions. In the validated model, leakage flow in five leakage paths and their effects on compressor efficiency was investigated. Results indicate that leakage can reduce volumetric efficiency by up to 50.2%, while the injected water liquid vaporization can improve volumetric efficiency by 7.9% at 5000 r center dot min(-1). The leakage through contact line (CL), tip sealing (TS) line, and discharge end face (DE) show the most important impact on compressor efficiency, while the leakage through blow hole (BH) and suction end face (SE) has little impact on compressor efficiency. Compared with zero leakage under certain conditions, the reduction of volumetric efficiency caused by CL, TS line, and DE can reach up to 22.4%, 20.4%, and 12.7%, respectively. Reducing clearances of the above three leakage paths can efficiently improve the performance of steam compressor, especially for CL.

关键词： Liquid water injection twin-screw steam compressor leakage heat and mass transfer performance optimization

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flow regime shift and temperature model of the radiation-induced convection system under surface cooling

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PHYSICS OF FLUIDS 2025年第3期37卷

作者： Zhou, Rui-Rui Yang, An-Wen You, Xiao-Gang Liu, Yun Sun, Ya-Song Li, Ling Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China Northwestern Polytech Univ Sch Power & Energy Shaanxi Key Lab Thermal Sci Aeroengine Syst Xian 710072 Peoples R China Changan Univ Sch Energy & Elect Engn Shaanxi Key Lab New Transportat Energy & Automot E Xian 710018 Peoples R China

The natural convection flow in the translucent fluid layer subjected to solar radiation heating plays a crucial role in the daytime heat and mass transfer in water bodies and solar energy collection. In a radiation-induced convection system under surface cooling, there are two possible flow regimes: the triple-layer and single-layer regimes. The flow regimes have a great influence on the mixing of fluid. The fluid is thermally stratified in the triple-layer regime, which should be avoided in the volumetric solar collector. In this paper, the transition condition of the flow regime shift between the triple-layer regime and the well-mixed single-layer regime is deduced since the thicknesses of the top and bottom mixing layers can be predicted through energy conservation analysis. Furthermore, a scaling analysis is conducted to obtain the scaling laws for the temperature differences across the thermal boundary layers regarding the control parameters, i.e., the Rayleigh number Ra, the Prandtl number Pr, the non-dimensional surface cooling heat flux phi, and the non-dimensional fluid depth H. A series of direct numerical simulations with the parameters in the range of 10(7) <= Ra <= 10(10), 0.7 <= Pr <= 70, 0 <= phi <= 0.7, and 0.5 <= H <= 3 are carried out to quantify the prefactor of scaling laws and also to validate the transition condition of the flow regime-shift. Then, a one-dimensional model can be developed to predict the temperature profile over the fluid depth with arbitrarily specified parameters. Thanks to the advantage of rapid and accurate prediction, this temperature model has a potential application for the design of the volumetric solar collector.

关键词： Prandtl number

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