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Enhanced electronic cooling with guest NCG microbubbles

APPLIED THERMAL engineering 2025年 272卷

作者： Luo, Peng Tong, Wei Wei, Lichuan Zhang, Jie Zhao, Yugang Zhang, Hua Cheng, Ping Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China Shenzhen Envicool Technol Co Ltd Shenzhen 518129 Peoples R China China Aerodynam Res & Dev Ctr Key Lab Icing & Anti Deicing Mianyang 621000 Sichuan Peoples R China Shanghai Jiao Tong Univ Sch Mech Engn Key Lab Power Machinery & Engn MOE Shanghai 200240 Peoples R China

Electrical and electronic devices are producing a higher density of heat along with their elevated performance to meet the booming needs of industrials and human activities, and in response, more effective cooling technologies are always in demand. Liquid immersion is one of the most popular cooling methods developed due to its thermal efficiency and operational feasibility. However, conventional single-phase immersion cooling exhibits relatively lower thermal efficiency and heat capacity, and dual-phase immersion cooling occurs only when the heating surface temperature exceeds the liquid boiling point, constraining the selection of suitable coolants. This work presents a cooling method using guest noncondensable gas (NCG) microbubbles to enhance heat transfer in immersion cooling. Direct experimental results show that the heat transfer rate increases drastically, and surface superheating is suppressed or even eliminated. NCG microbubbles can disturb the thermal boundary layer, serve as evaporation/boiling nuclei, and collide with existing bubbles to facilitate their departure. This cooling method performs better at a large degree of pool subcooling, while the effect of bubble size is relatively minor. The fundamental understanding of bubble dynamics upon impinging onto the heating surface in subcooled liquid has promising applications in thermal management systems, such as microelectronic chips, nuclear reactors, steam generators, and among others.

关键词： Noncondensable gas Microbubbles Immersion cooling heat transfer enhancement

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Experimental and Modeling of NOx Removal in Water under High Pressure Relevant to CO2 Compression and Purification Process

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INDUSTRIAL & engineering CHEMISTRY RESEARCH 2022年第41期61卷 15433-15446页

作者： Wang, Zhen Liu, Dunyu Chen, Jun Jin, Jing Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Univ Shanghai Sci & Technol Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China

Acid gas compression and purification are an effective way for the treatment of NOx in oxy-fuel combustion flue gas due to the reduced volume flow rate of flue gas in oxy-fuel combustion in comparison with air combustion. The design of reactors for NOx removal is particularly important for future CO2 utilization and storage and is also rather challenging due to the impact of pressure on both kinetic as well as mass-transfer parameters. To obtain the sensitivity as well as pressure dependence of different parameters, NOx removal in water under high pressure in both bubbling and film modes was investigated based on both experimental and modeling methods. Six uncertain parameters, including mass-transfer coefficients of NO and NO2 (kNO and kNO2), NO oxidation rate constant k1, liquid surface area S1, liquid film surface area S2, and liquid film volume VL, were identified and optimized to minimize relative errors between measurements and simulations. Three most important parameters affecting the simulated NOx absorption results are kNO2, k1, and S1, followed by kNO. While S2 and VL only affect NO2, these two parameters have little effect on NO, HNO3, and HNO2. In the gas bubbling reactor system, the liquid phase plays the main absorption role in NOx and the liquid film plays a supplementary absorption role. The effective removal of NOx in the high-pressure system can also be achieved by using only liquid film absorption rather than gas bubbling absorption as gas absorption by the liquid film can generate high concentrations of HNO3, which is beneficial for subsequent utilization.

关键词： Absorption Bubbles Gases Liquids Oxidation

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Numerical simulation study of indoor disinfection spray distribution based on CFD-DPM method

JOURNAL OF ENGINEERING RESEARCH

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JOURNAL OF engineering RESEARCH 2024年第3期12卷 562-570页

作者： Lu, Ye Li, Shen Xu, Wen Wang, Ying Dept Environm Hlth Zhejiang Prov Centerfor Dis Control & Prevent Hangzhou 310051 Peoples R China Sunlumos Disinfectant Shanghai Co Ltd Shanghai 202155 Peoples R China Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China

In today's world, environmental safety has become a top priority, with a special focus on terminal disinfection of indoor environments, which has proven to be a crucial and formidable issue in infection control. The use of hydrogen peroxide disinfection through vaporization or atomization presents a viable solution to the challenges posed by traditional wiping disinfection and ultraviolet disinfection methods that are plagued by incomplete disinfection and other factors that can significantly reduce the virus content within a room. To improve the application of hydrogen peroxide disinfection spray, the CFD-DPM (Computational Fluid Dynamics-Discrete Particle Model) method is employed to simulate the particle distribution of traditional sprays in a 30 m3 room. The study places emphasis on analyzing the impact of the placement position and bottle number of disinfection spray on the distribution of spray particles. The results demonstrate an impressive consistency between the numerical simulation method and experimental findings regarding the particle size distribution of disinfectant spray across various Schemes, validating the method's accuracy and reliability. However, the placement of a single disinfection spray source is insufficient to achieve uniformly distributed particles throughout the space when a bathroom is present within a given room. Nevertheless, by placing internal and external sources within the bathroom, the distribution of disinfectant spray particles becomes more even, thanks to a well conceived placement technique and an increased number of spray sources. Among all the schemes tested, Scheme 4 stands out for its ability to produce the greatest number of spray particles, with almost 60.71% of these particles remaining airborne for over 40 s. Therefore, it is also the most effective scheme for conducting disinfection.

关键词： Hydrogen peroxide disinfection spray DPM Particle existence time Disinfection

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The influences of the oil circulation ratio on the performance of a vapor injection scroll compressor in heat pump air conditioning system intended for electrical vehicles

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INTERNATIONAL JOURNAL OF REFRIGERATION 2023年 151卷 208-218页

作者： Li, Kang Ma, Jingru Cao, Jian Zhang, Bin Dou, Binlin Liu, Ni Zhang, Hua Su, Lin Zhou, Xuejin Tu, Ran 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 Huaqiao Univ Coll Mech Engn & Automat Xiamen 361021 Fujian Peoples R China

heat pump air conditioning (AC) based on a vapor injection scroll compressor has proven to be a promising solution to the current driving range limitations of electric vehicles (EV), especially in freezing climates. The lubricating oil inside the compressor is critical in promoting sealing and cooling, but it also exhibits a low performance under extreme working conditions. In addition, the effects of oil retention on compressor behavior and the optimal charge amount at low temperatures require further investigation. This paper adapts a second refrigerant calorimeter method to study the effects of different injection pressures on compressor performance. The results indicate that the mass flow rate, discharge temperature, compressor power consumption, and volume efficiency performance would increase significantly compared with the non-vapor injection (NV). The effects of oil circulation rate (OCR) on the performance of a vapor injection scroll compressor under two low-temperature operating conditions were also studied. The flow and heat transfer parameters were analyzed, and heating capacity was found to increase and decrease with enlarged OCR. The highest coefficient of heating performance (COP) was obtained at an OCR of 3.5% with a vapor injection pressure of 0.28 MPa. Compared with the nonvapor injection (NV) condition, the heating capacity and COP of the system at the same pressure of 0.28 MPa were increased by 6.2% and 1.8%, respectively. At extremely low temperatures, the heating capacity and COP were maximized at an OCR of 5.5% and an injection pressure of 0.45 MPa. Compared with that of NV, the heating capacity and COP of the heating system at the injection pressure were increased by 6.7% and 2.6%, respectively. The compressor discharge temperature decreased obviously with the increasing OCR. An empirical formula was devised to calculate the heating capacity for varying OCR.

关键词： Oil circulation rate Vapor injection Electric scroll compressor Compressor performance heating capacity

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Performance Analysis of Cooling Wall of Supercritical CO_(2) Coal-Fired Plants

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Journal of Thermal Science 2022年第6期31卷 1881-1890页

作者： WANG Yanjuan YU Binhui GAO Shuo LIU Qibin XU Jinliang The Beijing Key Laboratory of Multiphase Flow and Heat Transfer North China Electric Power UniversityBeijing 102206China Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

Using supercritical CO_(2)(S-CO_(2)) instead of water steam as heat transfer fluid for coal-fired power plants is another way to further improve the power generation efficiency. In this paper, a multi-field coupling model that integrates fluid flow, heat transfer and thermal stress is proposed to solve the complex problem. The effects of the key operating parameters on the performances of the cooling wall are numerically investigated. More details of the characteristics of fluid dynamics, thermal stress, pressure drop, coupled heat transfer and the whole flow and temperature fields in the S-CO_(2) cooling wall are revealed and discussed. A comparison study is made between the cooling wall tube and waterwall tube. Both temperature and thermal deformations of cooling wall tube are much higher than that of water. Numerical simulation results indicate that inclination angle has little effects on the temperature distribution, while increase of pressure drop is obvious as the inclination angle increases. Increasing tube diameter can effectively reduce both the pressure drop and the temperature of the cooling wall tube. As a result, a new insight is introduced for the design of S-CO_(2) power cycle.

关键词： supercritical CO_(2) cooling wall coal-fired power plant heat transfer

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Dynamic response analysis of floating wind turbine platform in local fatigue of mooring

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RENEWABLE ENERGY 2023年第1期204卷 733-749页

作者： Sun, Kang Xu, Zifei Li, Shujun Jin, Jiangtao Wang, Peilin Yue, Minnan Li, Chun Univ Shanghai Sci & Technol Energy & Power Engn Inst Shanghai 200093 Peoples R China Liverpool John Moores Univ Dept Marine & Mech Engn Liverpool L3 3AF England Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China

The moorings of the Floating Wind Turbine (FWT) platforms, long term suffering from the coupling loads of wind, waves and currents, are especially prone to structural fatigue. The purpose of this study is to mine effective information from the dynamic response of the FWT platform to achieve early damage detection for mooring health conditions. However, high nonlinearity of the FWT platform dynamic response, that is caused by the complexity of the working environment, hinders the accuracy of fatigue analysis and damage detection, Therefore, in this study, motivated by the accuracy of the chaotic features in quantifying nonlinearities and reliability of the convolutional neural network for feature extraction, an intelligent damage detection model, named Convolutional Neural Network-t-distribution Stochastic Neighbor Embedding (CNN-t-SNE), is proposed to automatically detect the damage magnitude of the moorings. Through analyzing the dynamics of FWT platform mooring from structure creep to failure, it is found that the yaw response is the most sensitive to structural damage. To examine the reliability of the proposed CNN-t-SNE method, the Lyapunov exponent and chaotic attractor quantify the nonlinearity of the features in the neural networks to indicate that the nonlinearity of the features decreases as the neural network layer deepens.

关键词： Floating wind turbine Fatigue Convolutional neural network Dynamic response Pattern recognition

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An Innovative Damping Random Walk Algorithm with Compulsive Evolution for the Synthesis of heat Exchanger Networks

SSRN

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SSRN 2024年

作者： Huang, Xiaohuang Liu, Weiwei Xu, Yue Xiao, Yuan Duan, Huanhuan Cui, Guomin Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China

The development of heat exchanger networks is considered a hot research topic within the chemical processing sector. In this regard, the proper design of heat exchanger networks significantly improves energy efficiency, reduces costs, and decreases carbon footprints. However, the design of optimal heat exchanger networks is often a challenge, primarily because the problem is characterized by nonlinear, nonconvex, and discontinuous attributes. Moreover, it is coupled with the prevalence of numerous local optima in the solution space. At a certain level of the optimization problem, the process becomes trapped in local extremes. Thus, the process will not be able to advance further, leading to a stagnation in the optimization. This study introduces an innovative damping Random Walk Algorithm with Compulsive Evolution (damping RWCE). The proposed method is an extension of the stochastic RWCE algorithm, which has received a lot of attention recently. The presented damping RWCE algorithm incorporates a damping coefficient to temper the acceptance of optimal solutions. This slows the rate of structural changes without undue interference. The added value of this approach lies in its thorough examination of both discrete and continuous variables, which, in turn, decreases the probability of neglecting potential solutions. This method successfully navigates out of local optima, increasing the likelihood of identifying the global optimum. To implement and evaluate the proposed method, three types of damping coefficients are defined. The method effectiveness is then validated, considering three case scenarios. The results demonstrated that the optimal total annual costs obtained in this study are more favorable compared to the optimal results listed in the literatures. © 2024, The Authors. All rights reserved.

关键词： Damping

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Laminar Flame Instability of n-Hexane,n-Octane,and n-Decane in Spherical Expanding Flames

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Journal of Thermal Science 2024年第3期33卷 1189-1199页

作者： YIN Geyuan HU Erjiang LI Xiaotian LV Xin HUANG Zuohua State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an710049China United Automotive Electronic Systems Co. LtdShanghai201206China Chongqing Changan Automobile Co. Ltd.Chongqing401120China

This paper focuses on the laminar flame instability of three high molecular weight n-alkanes,namely n-hexane,n-octane,and *** experiment was carried out in a constant volume combustion bomb to get the flame *** critical radius under different conditions was extracted using the image processing *** with the existing critical Peclet number theory,the dominant factors of flame instability under current conditions for three n-alkanes can be figured ***,the average cell size(equivalent cell radius,R_(cell))was extracted to provide quantitative analysis of the flame cellular structure,based on the method developed in this *** theoretical R_(cell)were also calculated and compared with the experimental results to validate the proposed method.

关键词： cellular instability equivalent cell radius critical Peclet number spherical flame

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Rapid Methane Hydrate Formation in Open-Cell Copper Foam 4th

Rapid Methane Hydrate Formation in Open-Cell Copper Foam

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4th International Technical Symposium on Deepwater Oil and Gas engineering and 3rd International Youth Forum on Gas Hydrate, DWOG-Hyd 2021

作者： Wang, Jiajie Yang, Liang Shao, Xinxin Zhang, Hao 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

ISBN: (纸本)9789811909597

Rapid methane hydrate formation with high gas storage capacity is very important for the application of natural gas hydrates technology. Three pieces of open-cell copper foam (CF) with different pore densities (or pores per inch, PPI) herein were immersed in sodium dodecyl sulfate (SDS) solution for enhancing methane storage in solid hydrate. The promotion effects of CF on the methane hydrate formation in the metal-embedded systems were investigated via an unstirred tank reactor. The results demonstrated that the surface of CF skeleton is covered with abundant micro holes and micro grooves, which can provide many metal nuclei for gas-water crystallization. The nest-like metal skeleton acts as crisscross "highway" for the crystallization heat transfer. Methane hydrate was quickly formed in the SDS/CF systems, but CF with the pore densities of 5 and 30 PPI was not favorable for conversion of more water to hydrate. Compared with these two composite systems, the SDS solution with the 15 PPI CF were able to store more methane at a faster formation rate. A theoretical model based highly porous two-phase systems was used to predict the effective thermal conductivity (ETC) of the metal foam filled with hydrate. It was found that the ETC of the hydrate/CF composite was significantly enhanced by employing CF matrix, and the low pore density CF had a more positive impact on improving the ETC of the composite. Further comparative experiments conducted at various pressures indicated that the solutions with 15 PPI CF exhibited higher methane storage capacities and larger hydration rates than the simple SDS solution, especially at the low pressure. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： Sodium dodecyl sulfate

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Numerical simulations of miscible displacement in an inclined channel by lattice Boltzmann method

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PHYSICS OF FLUIDS 2023年第3期35卷 1-17页

作者： Liu, Gaojie Wang, Yongqiang Zhang, Chunhua Lou, Qin 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 Southern Univ Sci & Technol Dept Mech & Aerosp Engn Guangdong Prov Key Lab Turbulence Res & Applicat Shenzhen 518055 Guangdong Peoples R China

The interfacial instability between miscible fluids in a channel is determined by many factors, such as viscosity contrast and the inclination angle. Considering the effect of the gravity field, we investigate the displacement phenomenon between two miscible fluids with different viscosities in an inclined channel. The results show that when the concentration Rayleigh number Ra-c < 10(5), the inclination angle theta ranges from 0 degrees to 90 degrees, and the natural logarithm of the viscosity ratio R>0;there are three fluid-fluid interfacial instability regions, namely, viscous fingering, "Kelvin-Helmholtz" (K-H) instability, and "Rayleigh-Taylor" (R-T) instability. A scaling analysis is developed to describe the time evolution of the displacement as described by the displacement efficiency at a fixed viscous ratio. Our analysis indicates that in the viscous fingering region, the time evolution of the displacement efficiency gradually increases with t scaling due to fingering formations;in the K-H and R-T regions, the displacement efficiency rapidly increases with t1(+RaC/106). When considering the effect of the viscosity ratio in the K-H instability region, the displacement efficiency scales as eta similar to R-t1+RaC/106(0.1). In addition, when the inclination angle is negative or R<0, the instability phenomenon is not obvious, and the displacement efficiency decreases as the inclination angle or R decreases.

关键词： Viscosity

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