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Research on refrigerant charge determination under different compressor speed and its effects on the performance of transcritical CO2 air-conditioning heat pump system in electric vehicle

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ENERGY 2024年 296卷

作者： Jiang, Ziqi Tian, Yafen Li, Kang Zhao, Zhaorui Liu, Ni Zhang, Hua Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Heat Transfer & Multiphase Flow Shanghai 200093 Peoples R China

CO2 is assumed to be one of the most potential refrigerant alternatives for electric vehicles for its excellent properties. However, the charge determination of CO2 in current studies remain controversial. In this study, a transcritical CO2 air-conditioning heat pump system was established and experimentally tested to analyze the optimal charge amount. Based on two conflicting methods of charge determining proposed by the preceding research, this paper substantiated the existing controversy and subsequently proposed a more comprehensive method. The effects of different refrigerant charge on the system characteristics were investigated. The influence of the compressor speed on the optimal refrigerant charge and system characteristics was also analyzed. It was found that the optimal charge plateau occurred from refrigerant of 500 g-580 g at the compressor speed of 3000 r center dot min(-1). However, the optimal charge declined with the increment of compressor speed from 3000 r center dot min(-1) to 4500 r center dot min(-1). Among three models, Hughmark's model was proved to be the most appropriate for the theoretical calculation of optimal charge within an error of 6.09%. Further study illustrates that refrigerant mass in high-pressure pipe and intermediate heat exchanger/accumulator (IHX/A) accounted for the main proportion about 52.6%-55.14%.

关键词： Transcritical CO2 refrigeration cycle Electrical vehicles heat pump Refrigerant charge amount

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Numerical simulation study of the fluid-structure coupling effects of Karman vortex street on airfoil motion with varying thickness

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OCEAN engineering 2023年第Part2期286卷

作者： Zhou, Zikang Huang, Shengxian Wang, Ying Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai Peoples R China

This paper examines the fluid-structure interaction of rigid and passive motion of airfoils with different thick-nesses in the K ' arm ' an vortex street at low Reynolds numbers through numerical simulations. Five NACA airfoils with varying thicknesses (8%, 12%, 16%, 20%, and 24%) were investigated regarding their fluid-structure interaction in the K ' arm ' an vortex street. These airfoils were positioned downstream along the centerline of a D-shaped cylinder. Employing a six-degree-of-freedom method, their passive motion was simulated, and the motion grid was generated using the elastic deformation method and local grid reconstruction technique. The analysis included examing alterations in the flow field and forces acting upon airfoils of varying thicknesses in both fixed and released states. The outcomes demonstrate that an increase in airfoil thickness amplified the traction force exerted on the airfoil within the K ' arm ' an vortex street, consequently yielding higher lateral force and torque. In the released state, the airfoil exhibited forward motion towards the D-shaped cylinder and deviated from the suction region of the K ' arm ' an vortex street due to the influence of lateral force. The study unveils that airfoils of suitable with appropriate thickness, such as NACA0012, achieved an improved equilib-rium between forward speed and lateral displacement, thereby covering a more extensive forward distance. These findings provide valuable insights for the designing robotic fish that utilize vortex streets under low-flow conditions.

关键词： Numerical simulation Fluid-structure interaction Airfoil thickness Passive motion

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Experimental and on-site investigation of the in-line vertical axis water turbines for water pipelines

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JOURNAL OF RENEWABLE AND SUSTAINABLE ENERGY 2021年第3期13卷 1-9页

作者： Chen, Jian Wang, Miao Li, Chun Sun, Li Yang, Liang Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer 516 Jungong Rd Shanghai Peoples R China

Health monitoring devices are critical for the safe and reliable operation of water supply systems, but their chemical batteries are easily depleted. Thus, this paper developed a micro-vertical axis water turbine that converts part of the water head into electrical energy and supplies power for the monitoring device. The performance of four groups of micro-turbines was investigated in detail through experimental testing. Different from our previous study, the entire performance curves of micro-turbines at different rotation speeds and flow velocities were obtained in order to consider the wide range of flow velocities inside the real water pipeline. The feasibility of the designed turbines in the power supply system was verified by on-site testing. The experimental results show that different types and opening sizes of blocks have a distinct influence on the output power of micro-turbines. Each type of block has the corresponding optimal opening size to gain the highest performance. Within a certain range, the maximum output power varies linearly with the increase in flow velocity. In a specific flow velocity, the optimal rotational speed of the micro-turbine generated the maximum output power can be predicted by the power curve. In addition, through the experimental data, it is found that among all the measured turbines, the 12-blade hollow shaft turbine with a 90% eye-shaped block is the best one, with an output power of 88.2 W and an efficiency of 15.76%. Finally, the results of an on-site test are consistent with that of the experiment properly, which verifies the reliability of the measured data in the laboratory.

关键词： flow velocity

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Theoretical Analysis of Thin Film Evaporation in the Wicks of Loop heat Pipes

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JOURNAL OF THERMAL SCIENCE AND engineering APPLICATIONS 2022年第5期14卷 051010页

作者： Lin, Bingyao Li, Nanxi Wang, Shiyue Tao, Leren Xu, Guangming Wu, Yinong 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 200093 Peoples R China Chinese Acad Sci Shanghai Inst Tech Phys Shanghai 200083 Peoples R China

In this paper, a thin film evaporation model that includes expressions for energy, mass, and momentum conservation was established through the augmented Young-Laplace model. Based on this model, the effects of pore size and superheating on heat transfer during thin film evaporation were analyzed. The influence of the wick diameter of the loop heat pipe (LHP) on the critical heat flux of the evaporator is analyzed theoretically. The results show that pore size and superheating mainly influence evaporation through changes in the length of the transition film and intrinsic meniscus. The contribution of the transition film area is mainly reflected in the heat transfer coefficient, and the contribution of the intrinsic meniscus area is mainly apparent in the quantity of heat that is transferred. When an LHP evaporator is operating in a state of surface evaporation, a higher heat transfer coefficient can be achieved using a smaller pore size.

关键词： evaporation heat transfer porous wick heat and mass transfer heat pipes heat transfer enhancement

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Numerical study on the performance of mixed flow blood pump with superhydrophobic surface

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MEDICAL & BIOLOGICAL engineering & COMPUTING 2023年第11期61卷 3103-3121页

作者： Li, Chengcheng Qiu, Huihe Ma, Jianying Wang, Ying Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China Hong Kong Univ Sci & Technol Dept Mech & Aerosp Engn Clear Water Bay Hong Kong Peoples R China Fudan Univ Shanghai Inst Cardiovasc Dis Zhongshan Hosp Dept Cardiol Shanghai 200032 Peoples R China

To meet the clinical status of the wide application of percutaneous mechanical circulatory support, this paper selects the mixed flow blood pump applied with superhydrophobic surface as the research object. The Navier slip model was used to simulate the slip characteristics of superhydrophobic surface, and the effects of the blade wrap angle and the superhydrophobic surface on the performance of the mixed flow blood pump are studied by numerical simulation. The results show that (1) considering the head, hydraulic efficiency, and hemolysis index of the blood pump, the optimal value of the blade wrap angle of the mixed flow blood pump in this paper is 60 degrees. (2) The hydraulic efficiency of the blood pump with superhydrophobic surface is improved, and the maximum growth rate is about 13.9%;superhydrophobic surface can reduce the hemolysis index of blood pump under various working conditions, and the maximum reduction rate of hemolysis index of blood pump is 22.9%. (3) The variation trends of blood pump head, hydraulic efficiency, and hemolysis index with the increased rotating speed before and after setting superhydrophobic slip boundary conditions are the same as their original variation trends.

关键词： Mixed flow blood pump Superhydrophobic surface Hemolysis index Blade wrap angles Numerical simulation

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Internal temperature and flame jet characteristics during thermal runaway triggered by nail penetration for NCM811 lithium-ion battery

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JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY 2022年第24期147卷 14925-14938页

作者： Wang, Haimin Yang, Zhen Jiang, Chenglong Ji, Zhiyuan Zhu, Zexu Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China China Automot Technol & Res Ctr Co Ltd Tianjin 300300 Peoples R China

The thermal runaway (TR) of NCM811 Lithium-ion battery (LIB) triggered by nail penetration was tested under three cases of full depth@100%SOC, half depth@100%SOC, and full depth@50%SOC, respectively. The internal temperature of the battery was measured by the built-in thermocouple, the fire behavior in four stages during TR was recorded by high-speed photography, the flame intensity was quantified by image processing method, and the internal structure of the battery was studied after TR. The results show that the effect of SOC on thermal runaway is more significant than that of penetration depth. In the case of full depth@100%SOC and full depth@50%SOC, the internal peak temperature is 887.3 degrees C and 483.2 degrees C, the maximum temperature difference between the internal and surface is 256.3 degrees C and 92.9 degrees C, the maximum jet angle is 72.0 degrees and 47.9 degrees, the jet area duty ratio is 41.2% and 17.8%, and the mass loss is 41.7 g and 18.6 g. For different cathode materials, the thermal runaway of NCM811 LIB is more serious than that of NCM532 LIB. For different trigger modes, the thermal runaway of NCM811 LIB triggered by nail penetration is more serious than that triggered by external overheating.

关键词： Thermal runaway Nail penetration Internal temperature Flame characteristics Image processing

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A Novel Mass-heat Exchange Network Analogy, Regression, and Synthesis Method for Mass Exchanger Networks

SSRN

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SSRN 2023年

作者： Xiao, Yuan Cui, Guomin Shanghai Key Laboratory Multiphase Flow and Heat Transfer in Power Engineering School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai20093 China

The mass exchanger network (MEN) synthesis is significant for material savings and pollution reduction in process industries. Considering its small magnitude and the concentration constraints, the optimized MEN configuration could easily violate the concentration constraints, leading to a reduction in the structural diversity during the optimization process compared to that of an heat exchanger network （HEN）of the same size. Moreover, the constraint on the mass transfer driving force based on the equilibrium composition might also have major effects on the optimization process. To address this, this paper presents a process-equipment-system analogy between the MEN and the HEN, proposing a novel mass-heat exchange network analogy, regression, and synthesis method. First, the generalized HEN was established by an analogy considering the MEN based on either the original or the equilibrium compositions. In this regard, a coordination coefficient was introduced to correct the deviation of the analogy relationship between the heat transfer and the mass transfer processes. Then, the generalized HEN was optimized by employing the random walk algorithm with compulsive evolution (RWCE). A regression method was proposed to regress the optimized HEN solution to the MEN expression, allowing the continuous optimization by the RWCE with finer parameters. The final optimal solution obtained is found to be lower than those reported in the literature with enhanced structural diversity, demonstrating the method’s effectiveness and providing new ideas for further synchronous optimization of combined heat and mass exchanger networks. © 2023, The Authors. All rights reserved.

关键词： Mass transfer

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Novel design of in-situ hydrogen sorption/storage integrated enhanced hydrogen production in supercritical CO2 gasification, air gasification, and steam gasification from biomass

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CHEMICAL engineering JOURNAL 2024年 485卷

作者： Yang, Tiebing Dou, Binlin Zhang, Hua Wu, Kai Luo, Ning Chen, Haisheng Xu, Yujie Li, Wei Wu, Chunfei 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 Queens Univ Belfast Sch Chem & Chem Engn Belfast BT7 1NN North Ireland

The novel process on in-situ hydrogen sorption/storage during water gas shift (WGS) was proposed and the enhanced hydrogen production in supercritical CO2 gasification (CG), air gasification (AG), and steam gasification (SG) from biomass was integrated. Pure hydrogen was obtained by regeneration from the material (Mg2Ni) used for in-situ H2 absorption during WGS. The effects of temperature, pressure, steam-to-carbon (S/C) ratio, and the quantity of adsorbent for the enhanced hydrogen production with in-situ hydrogen sorption/ storage were determined. When Mg2Ni was added as the in-situ H2 adsorbent, the hydrogen conversion in WGS reaction was improved. The increase of temperature reduced the hydrogen yield. SG presented the highest hydrogen yield and AG showed the highest hydrogen conversion. The steam-to-carbon (S/C) had a positive effect on the hydrogen production for all the processes and the methanation reaction was greatly inhibited by AG. The energy efficiencies reached 22.98 %, 26.31 %, and 27.149.51 %, and the exergy efficiencies reached 61.66 %, 64.19 %, and 83.62 %, for CG, AG and SG, respectively. The system energy can be supplied by in-situ hydrogen sorption/storage and the energy requirement order was SG > CG > AG.

关键词： In-situ hydrogen sorption/storage in WGS reaction SupercriticalCO2 gasification of biomass Air gasification of biomass Steam gasification of biomass Enhanced hydrogen production

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Application of PSO-LSSVM and hybrid programming to fault diagnosis of refrigeration systems

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SCIENCE AND TECHNOLOGY FOR THE BUILT ENVIRONMENT 2021年第5期27卷 592-607页

作者： Ren, Zhengxiong Han, Hua Cui, Xiaoyu Qing, Hong Ye, Huiyun Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer 516 Jungong Rd Shanghai 200093 Peoples R China

Fault detection and diagnosis (FDD) in refrigeration systems is of great importance for ensuring better equipment reliability and energy efficiency. Although numerous researches studied FDD algorithms and methodology, there is still a lack of mature commercial software in this field. This study presents a novel hybrid model by introducing particle swarm optimization (PSO) into least squares support vector machine (LSSVM) for parameter optimization to overcome the blindness of parameter selection, and proposes a novel idea of hybrid programming, where MATLAB is used to implement the FDD strategy and LabVIEW is employed for interface creation, to take the advantage of both sides. The hybrid programming is carried out through MATLAB script node, and an FDD platform for refrigeration systems is established. The strategy and the platform is validated using experimental data for a centrifugal chiller, where seven typical faults were investigated. The results show that the proposed PSO-LSSVM achieves an overall diagnostic accuracy of 99.70%, drastically improved (8.81%) from that of the LSSVM without optimization. The idea of hybrid programming is feasible for the establishment of an operable and highly integrated FDD platform with user-friendly interface and extendable functions. The practice of the idea also promotes the possibility of combining FDD with system control for better field applications.

关键词： MATLAB

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The Proposal and Calculation Method of the Annular Domain Weight Function for the Electromagnetic flowmeter Under Annular Conductivity Distribution

SSRN

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SSRN 2024年

作者： Yang, Yang Yang, Biaohu Zhang, Chao Yang, Bin School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering University of Shanghai for Science and Technology Shanghai200093 China

The electromagnetic flowmeter has many advantages, including non-invasiveness, absence of movable parts, high reliability, and insensitivity to physical properties of fluid such as density, temperature, pressure, and viscosity. However, it is susceptible to the impact of non-uniform distribution of medium conductivity. Therefore, studying the characteristic of weight function distribution under non-uniform conductivity distribution is of significant importance for expanding the engineering applications of electromagnetic flowmeter. This includes the case where the conductivity distribution is annular. In this paper, the influence of annular feature input parameters on the weight function distribution is explored by changing the radial distribution size and conductivity ratio of the center and outer ring under annular conductivity distribution. The research results indicate that annular feature input parameters will have complex effects on the distribution of weight function for electromagnetic flowmeter. However, an important finding is that the average value of the weight function within any small annular domain of the center or outer ring remains constant as the radial position changes. Therefore, this paper innovatively proposes the concept of ‘annular domain weight function’. It utilizes the average weight function of the center and outer ring to represent the contribution of the induced electromotive force generated by the average flow velocity within the center and outer ring under axisymmetric flow distribution to the potential difference between the two electrodes. Furthermore, the relationship between the ratio of the annular domain weight function of the center and outer ring and the annular feature input parameters is further studied. Ultimately, the expressions for calculating the weight function of the center and outer ring are obtained. This will be crucially significant for establishing theoretical response model for electromagnetic flowmeter under an

关键词： Distribution functions

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