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Simulation and evaluation study of atmospheric aerosol nonsphericity as a function of particle size

Particuology 2024年第7期90卷 281-291页

作者： qianjun mao Xin Nie School of Urban Construction Wuhan University of Science and TechnologyWuhan430065China College of New Energy and Materials Northeast Petroleum UniversityDaqing163318China

Aerosol nonsphericity causes great uncertainty in radiative forcing assessments and climate *** considerable studies have attempted to quantify this uncertainty,the relationship between aerosol nonsphericity and particle size is usually not considered,thus reducing the accuracy of the *** this study,a coupled inversion algorithm combining an improved stochastic particle swarm optimization algorithm and angular light scattering is used for the nonparametric estimation of aerosol nonsphericity variation with particle size,and the optimal sample selection method is employed to screen the *** on the verification of inversion accuracy,the variation of aerosol aspect ratio with particle size based on the ellipsoidal model in global regions has been obtained from Aerosol Robotic Network(AERONET)data,and the effect of nonsphericity on radiative forcing and dry deposition has been *** results show that the aspect ratio increases with particle size in all regions,with the maximum ranging from 1.4 to 1.8 in the desert,reflecting the differences in aerosol composition at different particle *** radiation calculations,considering aerosol nonsphericity makes the aerosol cooling effect weaker and surface radiative fluxes increase,but hardly changes the aerosol absorption,with maximum differences of 9.22%and 22.12%at the bottom and top of the atmosphere,***,the differences in radiative forcing between aspect ratios as a function of particle size and not varying with particle size are not significant,averaging less than 2%.Besides,the aspect ratio not varying with particle size underestimates the deposition velocity of small particles and overestimates that of large particles compared to that as a function of particle size,with maximum differences of 7%and 4%,respectively.

关键词： Aerosol nonsphericity Inversion Aspect ratio Radiative forcing Dry deposition velocity

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Numerical analysis on phase change material melting process of a conical spiral tube energy storage tank

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Science China(Technological Sciences) 2024年第11期67卷 3413-3430页

作者： ZHAO Yuan mao qianjun School of Urban Construction Wuhan University of Science and TechnologyWuhan 430065China

Spiral tube heat exchangers have been widely used in phase change energy storage due to the compact structure and large heat transfer ***,this study numerically analyzes the effects of spiral tube diameter,number of rotations,and unsteady heat source on the melting process in conical spiral tube energy storage tanks using Fluent *** results indicate that when the tube diameter is increased from 8 to 11 mm and the number of rotations is increased from 5 to 8,the melting time is extended by 15.74%and 17.83%,*** energy storage capacity increases by 0.64%and 1.83%,*** average energy storage rate decreases by 13.05%and 13.58%,***,the sinusoidal wave heat source with small heat source periods has little effect on the melting process,while large heat source periods can significantly accelerate the *** the influence of amplitudes on the thermal storage performance under large heat source periods is more *** the heat source period is increased from 2 to 160 min and the amplitude is increased from 5 to 20 K,the melting time is reduced by 24.50%and 17.20%,*** total energy storage capacity decreases by 6.36%and increases by 1.62%,*** average energy storage rate increases by 24.03%and 22.74%,*** study provides guidance for the performance optimization of spiral tube phase change systems.

关键词： phase change material melting conical spiral tube periodic unsteady heat source

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Comparative investigation on the heat transfer performance of an energy storage system with a spiral tube and straight tube:An experimental approach

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Science China(Technological Sciences) 2023年第1期66卷 71-85页

作者： mao qianjun CAO Yan LI Tao School of Urban Construction Wuhan University of Science and TechnologyWuhan 430065China

Latent heat thermal energy storage systems can effectively fill the gap between energy storage and application, and phase-change materials(PCMs) are crucial media for storing thermal energy. Therefore, how to maximize the utilization efficiency of PCMs has attracted widespread attention. In this study, the thermal behavior of two thermal storage units employing a spiral tube and straight tube as heat transfer tubes was experimentally researched and comprehensively compared. Stefan numbers were used to investigate the impact of the heat transfer fluid temperature on the PCM melting process. The temperature distribution of PCMs,temporal evolution of the melting front, and temperature variations of measurement points in both tanks were compared. The average temperature and energy storage of PCMs were calculated to evaluate the thermal performance of different configurations. The results indicate that compared to cylinder B(with a straight tube), the energy storage in cylinder A(with a spiral tube)increased by 78.8%, 38.5%, and 19.6% at Stefan numbers of 1.08, 1.28, and 1.48, respectively. Moreover, the increase in the Stefan number simultaneously ascended the average temperature and energy storage of PCMs in containers A and B, causing the shortening of the melting time. When the Stefan number was increased from 1.28 to 1.48, the storage capacity was raised from3233.18 to 3463.8 k J, and the total melting time was decreased by 34.2% from 547.5 to 360 min after the PCM was loaded in cylinder A. The research results lay a certain foundation for a deeper study of enhanced heat transfer in spiral tubes.

关键词： thermal energy storage visualization experiment PCM spiral tube straight tube

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Heat Storage Performance of PCM in a Novel Vertical Pointer-Shaped Finned Latent Heat Tank

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Journal of Thermal Science 2024年第2期33卷 422-434页

作者： mao qianjun ZHU Yuanyuan LI Tao School of Urban Construction Wuhan University of Science and TechnologyWuhan430065China

The heat storage performance of latent heat storage systems is not good due to the poor thermal conductivity of phase change *** this paper,a new type of pointer-shaped fins combining rectangular and triangular fins has been employed to numerically simulate the melting process in the heat storage tank,and the fin geometry parameter effects on heat storage performance have been *** results indicate that compared with the bare tube and the rectangular finned tank,the melting time of the phase change material in the pointer-shaped finned tank is reduced by 64.2%and 15.1%,*** closer the tip of the triangular fin is to the hot wall,the better the heat transfer *** optimal height of the triangular fin is about 8 *** the number of fins from 4 to 6 and from 6 to 8 reduces the melting time by 16.0%and 16.7%***,increasing the number of fins from 8 to 10 only reduces the melting time by 8.4%.When the fin dimensionless length is increased from 0.3 to 0.5 and from 0.5 to 0.7,the melting time is shortened by 17.5%and 13.0%.But the melting time is only reduced by 2.9%when the dimensionless fin length is increased from 0.7 to *** optimising the design of the thermal storage system,the results can provide a reference value.

关键词： thermal energy storage phase change material pointer-shaped fins heat storage performance

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Energy Storage Performance of a PCM in the Solar Storage Tank

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Journal of Thermal Science 2019年第2期28卷 195-203页

作者： mao qianjun CHEN Hongzhang YANG Yizhi School of Urban Construction Wuhan University of Science and Technology

High-temperature solar thermal power station with solar energy storage is one of the effective ways to solve energy shortage and environmental pollution. The heat storage characteristics of phase change materials in solar energy storage tanks directly affect the performance of the system and its future promotion and utilization. Based on the knowledge of heat transfer, fluid mechanics and engineering thermodynamics, this paper uses MATLAB software to compile the dynamic heat storage characteristics calculation program of phase change materials in energy storage tanks, and verify the results. This paper analyzes the phase change heat storage process with three PCM initial temperatures and three HTF speeds. The results show that when the initial temperature of the PCM changes from 185°C to 210°C, the latent heat storage heat increases by 21.8%, and the total heat storage decreases. Increasing the HTF speed from 1.8 m/s to 2.2 m/s, the melting time was reduced from 414 minutes to 390 minutes, and the total heat storage and sensible heat storage were also increased. The results also show that changing the initial temperature of the PCM and the flow rate of the HTF will change the thermal storage performance of the system. The research has certain reference significance for mastering the basic principle of high temperature solar thermal power generation system and promoting the application of the system.

关键词： solar phase change materials energy storage performance sensible heat latent heat

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Numerical and Experimental Investigation on Heat Transfer Performance of a Solar Single Storage Tank

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Journal of Thermal Science 2021年第5期30卷 1596-1606页

作者： mao qianjun LI Ying ZHANG Yamei ZHANG Chunzhi School of Urban Construction Wuhan University of Science and TechnologyWuhan430065China

The single-tank latent heat thermal energy storage(LHTES)of solar energy mainly consists of two modules:the first one is the phase change material(PCM)module heated by solar energy;the second is a module of heat transfer between melted PCM and the user’s low-temperature *** paper mainly focuses on the former *** investigate the heat transfer performance of the paraffin-based solar single storage tank and find a more suitable experimental configuration,as basic research work,we established a single-tank thermal storage platform and then conducted a numerical simulation on the heat transfer process with *** result of numerical simulation shows that the test situation was basically reflected and the data agreed well with the experiment *** numerical simulation analysis is accurate and the method is *** obtain the heat transfer performance of paraffin in a single tank and strengthen heat transfer,the aspect ratio,the melting temperature of paraffin,and the heating power of the electric heater were analyzed based on *** results show that the heat transfer gets more uniform when the aspect ratio is *** results in an increase in the liquid fraction of 61.83%to 76.47%one hour after heating when the aspect ratio of the tank reduced from 2.8 to *** higher the melting temperature of paraffin,the longer it takes for PCM to reach a stable *** the curvature of liquid heating is greater than that of solid heating at the bottom *** the constant total work,the heating power has little effect on the heat transfer performance of the *** study will provide some reference value for the optimization design of single-tank LHTES systems in the future.

关键词： LHTES single tank PCM numerical simulation

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Performance of MODIS aerosol products at various timescales and in different pollution conditions over eastern Asia

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Science China(Technological Sciences) 2021年第4期64卷 774-784页

作者： mao qianjun HUANG ChunLin ZHANG HengXing CHEN QiXiang YUAN Yuan School of Urban Construction Wuhan University of Science and TechnologyWuhan 430065China Key Laboratory of Aerospace Thermophysics Ministry of Industry and Information TechnologyHarbin Institute of TechnologyHarbin 150001China

High-quality aerosol optical depth(AOD)data derived from MODIS is widely used in studying spatiotemporal trends of fine particulate matter(PM2.5)concentrations in eastern ***,the differences of MODIS-AOD(3/10 km DT;10 km DB)under four pollution situations(No-Po;Sl-Po;Mo-Po;Se-Po)are rarely *** this study,the MODIS-AOD and AODDifference spatial distributions from 2008 to 2017 are analyzed through annual/seasonal mean AOD maps generated at 0.1°×0.1°*** MODIS-AOD performances are validated using AERONET AOD data for various pollution situations and aerosol *** validations indicate that the 10-km DB algorithm provides the best performance,followed by 3-km DTand 10 km *** DB algorithm can provide spatially continuous AOD data for all seasons,whereas the DT algorithm often fails to yield valid data during *** validations under different pollution conditions illustrate that severe pollution significantly affects the validity of data obtained by the DB ***,the accuracy of DT-derived AOD data is robust against *** the same pollution conditions,the correlation coefficient of the DB algorithm is smaller than that of the DT *** quantity of valid data in the DB product is higher than those in DT products for all pollution conditions,especially under Se-Po.

关键词： aerosol optical depth MODIS DT algorithm DB algorithm pollution conditions

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典型雾霾粒子及团簇的散射吸湿增长特性

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光学学报 2020年第24期40卷 178-186页

作者：毛前军王莉武汉科技大学城市建设学院湖北武汉430065

为探究雾霾粒子吸湿性引起的散射吸湿增长特性,基于雾霾粒子湿度增长模型,利用Mie散射理论和多球T矩阵计算方法,详细研究了硫酸、硫酸铵、沙尘、硝酸铵以及碳质气溶胶5种典型雾霾粒子及其团簇在入射波长为532 nm、相对湿度在60%~95%范... 详细信息

为探究雾霾粒子吸湿性引起的散射吸湿增长特性,基于雾霾粒子湿度增长模型,利用Mie散射理论和多球T矩阵计算方法,详细研究了硫酸、硫酸铵、沙尘、硝酸铵以及碳质气溶胶5种典型雾霾粒子及其团簇在入射波长为532 nm、相对湿度在60%~95%范围内的散射吸湿增长特性。研究结果表明:对单一雾霾粒子,硫酸、硫酸铵以及硝酸铵这类二次水溶性无机粒子及其团簇的散射吸湿增长较突出,沙尘较为平缓,而碳质气溶胶则呈现抑制作用,同时,小粒径粒子的散射吸湿增长因子呈指数增长,而大粒径粒子则呈波动、负增长趋势;对于雾霾粒子的团簇,散射吸湿增长因子曲线整体增幅减小,粒子团簇的体积分数对散射吸湿的影响明显,随着体积分数的增加,散射吸湿增长因子曲线的波动频率增大,同时振幅减小,但整体呈现的吸湿增长还是由团簇粒子的粒径范围与成分决定,其中团簇粒径范围影响较大。这为探究雾霾粒子散射吸湿增长特性和研究大气污染提供了理论支持。

关键词：散射雾霾粒子 Mie散射多球T矩阵散射吸湿增长因子

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非等距螺旋管壳式相变系统的蓄热性能研究

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中南大学学报（自然科学版） 2022年第12期53卷 4789-4798页

作者：毛前军曹燕武汉科技大学城市建设学院湖北武汉430065

针对垂直等螺距螺旋管壳式相变蓄热系统中相变材料上下受热不均匀的问题,首先,提出了3种不同压缩比的变螺距螺旋换热管结构;其次,数值模拟了不同压缩比螺旋管蓄热单元中相变材料加载过程;再次,讨论了4个蓄热罐中温度场和相界面的变化趋... 详细信息

针对垂直等螺距螺旋管壳式相变蓄热系统中相变材料上下受热不均匀的问题,首先,提出了3种不同压缩比的变螺距螺旋换热管结构;其次,数值模拟了不同压缩比螺旋管蓄热单元中相变材料加载过程;再次,讨论了4个蓄热罐中温度场和相界面的变化趋势,分析了液相分数与斯蒂芬数随傅里叶数的变化规律;最后,对比了不同配置下相变材料的加载时间、平均储能速率和储能量。研究结果表明:压缩后的换热管可以有效促进圆柱形蓄热罐底部沉降相变材料的熔化,减轻蓄热罐内温度垂直分层现象,强化液体相变材料之间的自然对流,提升等距螺旋管壳式潜热蓄热系统的热性能;与同等条件下的等距螺旋管相比,使用压缩比为2和3的螺旋管,其完全熔化时间分别减少了10.2%和16.6%,平均储能速率分别提高了16.1%和22.6%。此外,当压缩比增加到5时,系统加载时间不降反增,平均储能速率略有下降。

关键词：非等距螺旋管压缩比相变蓄热系统相变材料蓄热性能

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基于磁激元的嵌套环超材料吸波器的吸收特性

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光学学报 2019年第8期39卷 247-254页

作者：毛前军冯春早武汉科技大学城市建设学院

多频段超材料完美吸波器的设计在多色光学领域具有重要意义。提出一种多频段金属-绝缘层-金属超材料吸波器,其表面电磁响应单元为三圈嵌套的金属环阵列,采用时域有限差分方法计算结构单元的吸收光谱和电磁场密度分布。结果表明:该结构... 详细信息

多频段超材料完美吸波器的设计在多色光学领域具有重要意义。提出一种多频段金属-绝缘层-金属超材料吸波器,其表面电磁响应单元为三圈嵌套的金属环阵列,采用时域有限差分方法计算结构单元的吸收光谱和电磁场密度分布。结果表明:该结构单元在1.44,2.28,3.25μm处分别实现了98.5%、99.6%和99.9%的吸收率,物理机理为磁激元共振激发。系统分析结构几何参数对共振的影响,通过改变金属环的直径和高度,可以对不同的共振进行独立调控。该结构单元的吸收光谱对入射光极化角度具有良好的稳健性。并进一步分析了超材料吸波器的传感特性,其最大品质因数高达8.3 RIU-1(RIU为折射率单元),对应的灵敏度为1.08μm·RIU-1,表现出优良的红外传感性能。该吸波器可应用于传感领域,亦可为其他超材料的设计带来新启示。

关键词：材料吸波器超材料磁激元共振

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