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Influence of lubricating oil circulation characteristics on the performance of electric vehicle heat pump system under low temperature conditions

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APPLIED THERMAL engineering 2024年第PartB期236卷

作者： Li, Kang Kong, Fanyue Luo, Shuxian Liu, Ni Zhang, Hua Dou, Binlin Zhao, Yugang Zhou, Xuejin Tu, Ran Su, Lin He, Qize Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Univ Shanghai Sci & Technol Key Lab Multiphase Flow & Heat Transfer Shanghai P Shanghai 200093 Peoples R China Pan Asia Tech Automot Ctr Co Ltd Shanghai 201201 Peoples R China Shanghai Fire Res Inst MEM Shanghai 200093 Peoples R China Huaqiao Univ Coll Mech Engn & Automat Xiamen 361021 Fujian Peoples R China

Electric vehicles frequently employ heat pump systems for winter heating. In winter low-temperature environments, the viscosity of lubricating oil increases, forming an oil film as the refrigerant enters the heat exchanger, consequently impacting the heat transfer efficiency and overall performance of the heat pump system. This paper presents the design and implementation of an experimental heat pump system tailored for electric vehicles. The experimental setup incorporates a specialized device for lubricating oil sampling and an assessment methodology for evaluating heat pump functionality. Under a range of low-temperature conditions, the system underwent comprehensive testing, enabling a detailed analysis and synthesis of the flow characteristics and the influence of lubricating oil within both the heat pump system and the heat exchanger. The results reveal that the oil circulation rate is directly affected by the compressor oil charge, and maintaining the oil circulation rate within the range of 3 %-4 % results in a peak COP of the system. When the ambient temperature is 0 degree celsius and the oil filling volume is 200 g, the oil circulation rate is 3.87 %, and the COP can reach 1.93. In addition, as the oil retention in the evaporator increases by 15.67 g, the COP value decreases by 21 %. Similarly, the increase in oil retention in the condenser from 2.43 g to 6.25 g resulted in a corresponding decrease in heat transfer capacity of 0.07 kW/K, leading to an overall deterioration of the system's performance.

关键词： Electric vehicle Oil retention heat pump system Oil circulation rate heat pump performance

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Enhancing Vertical-Axis Tidal Turbines with Strategic Superhydrophobic Surfaces for Optimized Aerodynamic and Self-Starting Performances

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SSRN 2024年

作者： Yin, Dawei Sun, Jinjing School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China Shanghai Key Laboratory of Power Energy in Multiphase Flow and Heat Transfer Shanghai200093 China

As observation and research on nature deepen, bionic and hydrophobic surface drag reduction are gaining increasing popularity among researchers. The application of bionic principles and hydrophobic surface technologies in the field of fluid dynamics has opened up new avenues for enhancing the performance of various engineering systems, including vertical-axis tidal turbines (VATTs). By mimicking the natural mechanisms observed in certain species, such as the lotus effect, researchers have been able to develop superhydrophobic surfaces (SHS) that significantly reduce drag in fluid ***, SHS have been applied uniformly across the entire surface of an airfoil. However, this study takes a more nuanced approach by investigating the impact of SHS application at different positions on the airfoil. Through numerical simulations, the study explores how varying the distribution of SHS can influence the power coefficient (Cp), a key performance metric for VATTs . The findings from the study are quite revealing. At a tip speed ratio (TSR) of 1.68, the study observes that applying SHS to 30% of the chord length near the leading edge of the airfoil yields the maximum relative power coefficient benefit, with an increase of up to 34.8%. This suggests that strategic placement of SHS can lead to significant performance improvements without the need for uniform application, which could potentially reduce material costs and maintenance requirements. Moreover, the study also finds that applying SHS only on the inner surface of the VATT can result in a 32% increase in the power coefficient. This indicates that the inner side of the airfoil, which experiences the higher pressure side of the fluid flow, is particularly sensitive to the drag reduction effects of SHS. The leading edge of the airfoil is another critical area where SHS application can have a substantial impact. The leading edge is the first point of contact between the airfoil and the fluid, and any reduc

关键词： Drag reduction

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Dynamic performance optimization of a floating offshore wind turbine based on fractal-inspired design principles

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ENERGY 2025年 324卷

作者： Huang, Haoda Liu, Qingsong Bashir, Musa Malkeson, Sean Li, Chun Yue, Minnan Miao, Weipao Wang, Jin 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 Univ Liverpool Sch Engn Brownlow Hill L69 3GH England Liverpool John Moores Univ Offshore & Marine LOOM Res Inst Liverpool Logist Byrom St Liverpool L3 3AF England

As the development of onshore and fixed offshore wind turbines approaches saturation, floating offshore wind turbines (FOWTs) are increasingly gaining attention due to their ability to operate in deeper waters and harness more stable wind resources. However, the dynamic responses of FOWTs are amplified significantly under the complex sea conditions, posing challenges to the overall system stability. This study proposes a novel semisubmersible platform featuring fractal structure inspired by Victoria Amazonica as solutions to the overall system stability of FOWTs. The computational fluid dynamics method, integrated with dynamic fluid-body interaction and volume of fluid wave model, is used to examine the aero, hydro, and mooring dynamics of the FOWT. A parametric model of the fractal structure with different branch levels is constructed by recursive method. Firstly, the hydrodynamic performance of the novel platforms with multi-level branch structures is examined under single wave conditions. The results show that vortices in fractal structures present higher velocity gradients and greater viscous dissipation, thereby effectively absorbing wave energy. The stability of the platform improves progressively as the branch levels increase. Subsequently, the dynamic responses of the fullconfiguration FOWT mounted on the platform with 8-level fractal structure (8LFS-FOWT) are further evaluated under wind-wave coupling conditions. The results reveal that 8LFS-FOWT achieves superior hydrodynamic performance with the most notable improvement in pitch amplitude of 25.22 % decrease. This enhancement also brings a 12.75 % reduction in the standard deviation of power output, forming positive feedback to ensure safe and stable operation of the system. The findings provide a valuable reference for promoting the innovative platform design of FOWTs.

关键词： Floating offshore wind turbine Leaf-vein structure Computational fluid dynamics Fractal dimension Fully coupled dynamic response

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Pore-scale simulation of miscible displacement in an inclined porous medium

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FRONTIERS IN ENERGY RESEARCH 2024年 12卷

作者： Liu, Gaojie Xu, Aoyu Wang, Yongqiang Lou, Qin Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai Peoples R China

Introduction: This study investigates the displacement of two miscible fluids within an inclined porous medium at the pore scale, highlighting how the pore-scale microstructure, inclination angle, and viscosity ratio affect the interfacial instability between two fluids during displacement processes. Methods: The lattice Boltzmann Method (LBM) is employed to solve the governing equations. Two distribution functions are used to simulate the velocity field and the concentration field, respectively. Results and discussion: An increase in inclination angle exacerbates the interfacial instability between fluids and the viscous fingering phenomenon. This viscous fingering expands the sweep range of displacing fluids, which improves the displacement efficiency. When theta > 50(degrees), further increase in inclination angle will not cause significant changes in displacement efficiency. In addition, the viscosity ratio is a key factor affecting displacement efficiency. The larger the viscosity ratio, the greater the displacement efficiency. Furthermore, the critical viscosity ratio has been found, and any increase in the viscosity ratio above the critical value will not affect the displacement efficiency.

关键词： miscible displacement viscous fingering inclined porous media displacement efficiency lattice Boltzmann method

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Insights on CDI parametric controls and dependencies using gloabal sensitivity analysis

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SEPARATION AND PURIFICATION TECHNOLOGY 2025年第Part8期354卷

作者： Qin, Huai Fang, Fang Mao, Yunfeng Xu, Longqian Wu, Deli 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 Zhejiang Prov Ind EP Design & Res Inst Co Ltd Shangyu 310013 Zhejiang Peoples R China Tongji Univ Coll Environm Sci & Engn State Key Lab Pollut Control & Resources Reuse Shanghai 200092 Peoples R China Vanderbilt Univ Dept Civil & Environm Engn Nashville TN 37235 USA

Capacitive deionization (CDI) emerges as a promising desalination technology due to its high energy efficiency and potential for energy recovery. Its performance improvement and application extension highly require understanding how variations in multiple input parameters, as well as their interactions, lead to variations in output, which is not straightforward in the complex system of CDI. In this work we use the extended Fourier amplitude sensitivity test (eFAST) method to conduct a global sensitivity analysis (GSA) in order to examine the effects of several parameters, including material properties, operating conditions, and ionic properties, on the energy consumption and salt removal efficiency of CDIs. The research reveals that high capacitance and efficient mass transfer are crucial for CDI advancement, with a trade-off between desalination rate and energy efficiency. The interplay between input parameters is revealed by factorial design and GSA, which show that no single parameter alone determines salt adsorption capacity but that feedwater salt concentration and current density are important when considering both individual and coupled effects. The study suggests that the specific application and feedwater characteristics should be taken into consideration when deciding between the CC and CV modes of desalination. While CC mode excels in water production and energy efficiency for high salinity feedwater pretreatment, CV mode is better at treating low salinity waterr. The comprehensive parametric analysis provides valuable insights into optimizing CDI design and operating conditions to balance desalination capacity and energy efficiency.

关键词： Capacitive deionization Mass transfer model Global sensitivity analysis Constant current mode Constant voltage mode

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Study on the Three-Dimensional flow Control of Two-Phase flow Around a Cylinder by an Attached Cylinder

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SSRN 2023年

作者： Xia, Yizhan Hu, Yu Huang, Shengxian Wang, Ying Shanghai key laboratory of multiphase flow and heat transfer of power engineering School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai China

Enhancing the separation of flow, shedding of vortices, and sediment deposition around blunt bodies, particularly in cylindrical flows within the realm of ocean engineering, emerges as a pivotal safety factor. This study delves into the control of two-phase flow encircling a cylinder using an affixed cylinder under three-dimensional real ocean conditions. Employing the SST turbulence model, a two-dimensional incompressible RANS numerical simulation is performed. Initially, the influence of varying gap ratios between the auxiliary small cylinder and the main cylinder is scrutinized. Subsequently, the impact of attached small cylinders on the flow field surrounding the main cylinder is examined under different particle characteristics. Lastly, employing the UDF function, four small cylinders exhibiting distinct vibration modes are defined, and the numerical simulation investigates the effects of Grain flow on particle flow and distribution in the wake region of the main cylinder. © 2023, The Authors. All rights reserved.

关键词： Cylinders (shapes)

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Numerical simulation of heat and mass transfer during sublimation drying of porcine aorta

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DRYING TECHNOLOGY 2022年第11期40卷 2260-2273页

作者： Gui, Chao Tao, Leren Yang, Weifang Zhang, Yaqi Chen, Shanshan Shen, Daoming Yang, Lele Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Peoples R China Xinxiang Univ Sch Civil Engn & Architecture Xinxiang Henan Peoples R China Univ Shanghai Sci & Technol Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai Peoples R China

Freeze-drying is an effective method for aortal preservation. However, there are few studies on heat and mass transfer of aortal freeze-drying. In this study, the contactless weighing device was used to monitor freeze-drying process. The radiation view factor of the aortal segment was estimated, and the quasi-steady state model was used to analyze heat and mass transfer, there was a certain amount of heat flux in the frozen layer, which provided sublimation heat for internal sublimation interface. By theoretical calculation, the vapor diffusion coefficient was determined. The unsteady state model was used for numerical simulation. The simulated result of free water removal ratio was consistent with experiment result. Both heat flux density and mass flux density decreased non-linearly in the early stage, but approximately linearly in the late stage. The velocity of inner and outer sublimation interfaces was almost the same. The nodes temperature gradually increased and finally approached the heating temperature, and the temperature gradient of both dried and frozen layers decreased gradually with drying time. The water vapor pressure gradient was smaller near the aortal wall and larger in the middle region.

关键词： Freeze-drying sublimation numerical simulation heat and mass transfer diffusion coefficient

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Melting characteristics and dynamic evolution of microstructure of single-crystal gold film irradiated by laser under the non-Fourier effect

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MOLECULAR CRYSTALS AND LIQUID CRYSTALS 2021年第1期723卷 62-79页

作者： Wang, Qing Li, Ling Yang, Mo Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai Peoples R China

The process of ultra-thin single crystal gold film irradiated by femtosecond laser is simulated by the combination of improved two-temperature model (TTM) and molecular dynamics (MD). The results indicate that under the non-Fourier effect, the gold film shows special melting characteristics and spalling mechanism. The phenomena of homogeneous melting and pore spalling of gold film are successfully distinguished by curing rate method and atomic density method respectively. Due to the tiny thickness of the gold film studied, the damage mechanism of the gold film irradiated by laser has also changed.

关键词： Femtosecond laser melting characteristics metal film non-Fourier effect spalling damage

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Experimental investigation on thermal performance of a pumped two-phase battery cooling system using mini-channel cold plate

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INTERNATIONAL JOURNAL OF ENERGY RESEARCH 2021年第11期45卷 16078-16090页

作者： Xu, Dan Fang, Yidong Hu, Lingren Yang, Wenliang Su, Lin Univ Shanghai Sci & Technol Coll Energy & Power Engn Shanghai Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai Peoples R China

This study presents an experimental investigation on a pumped two-phase battery cooling system using R1233zd(E) as the refrigerant. The thermodynamic cycle of the system, together with the heat transfer and pressure drop characteristics of the mini-channel cold plate, were analyzed under different conditions. Results showed that the pressure rise of the pump was increased under higher heat flux and mass flux, and the overall system pressure was elevated when the coolant bath temperature was raised. The effects of the mass flux on the overall heat transfer coefficient of the cold plate were different under various heat fluxes, while pressure loss of the cold plate showed a dramatic rise after the heat flux was over 2 W center dot cm(-2). The average temperature of the cold plate was generally decreased with the increasing mass flux, while the maximum temperature difference was nearly constant when the heat transfer was dominated by single-phase forced convection. However, the maximum temperature difference could be lowered after flow boiling became dominant. In addition, the local heat transfer characteristics for different channels and the temperature uniformity in the cold plate were investigated. It was found that the local temperature was increased and then stabilized along the flow direction, while the local heat transfer coefficient was increased monotonously. Meanwhile, lower local temperature and higher heat transfer coefficient were found in the upper channel for the intensive boiling with lower mass flux which compared to the middle channel. Novelty Statement This study investigated the performance of a pumped two-phase battery cooling system using mini-channel plate under higher heat flux and discussed the reasons for wall temperature variation and temperature uniformity under different heat transfer mechanisms.

关键词： mini‐ channel pumped two‐ phase system temperature uniformity thermal performance

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Exergy Analysis of a Novel Chemical Looping Hydrogen Generation System Integrated with SOFC

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Journal of Thermal Science 2021年第1期30卷 313-323页

作者： ZHANG Xiaosong CHEN Zhewen CHEN Zhenbin LI Jinsong Mechanical and Electrical Engineering College Hainan UniversityHaikou 570228China Beijing Key Laboratory of Multiphase Flow and Heat Transfer North China Electric Power UniversityBeijing 102206China

In this paper,a novel system integrating chemical-looping hydrogen generation(CLH)system and solid oxide fuel cell(SOFC)has been *** new methane-fuelled energy system was investigated with energy balance and exergy *** produces the hydrogen as the fuel of the SOFC,and the Fe O and Fe3O4 are selected as the looping *** heat from the SOFC is absorbed by the CLH and converted to chemical energy through the reduction reaction of *** to the cascade utilization of the fuel between the CLH and SOFC,the net efficiency of this novel system can achieve 62.8%considering CO_(2)separation,more than 10 percentage points higher than a methane reforming fuelled SOFC ***,by using the CLH to produce the hydrogen,the CO_(2)can be recovered without an energy *** the analysis of the graphical exergy,the cascade utilization of waste heat and the high-efficiency hydrogen production is the main reason of high *** novel system also has the advantage of CO_(2)capture without energy penalty,so this combined system is an advantaged method to accomplish the efficient utilization of methane.

关键词： chemical looping fuel cell exergy analysis

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