尘埃粒子计数器的检测和校准现状

尘埃粒子计数器是用来评价洁净环境洁净度等级的重要仪器,近年来,尘埃粒子计数器的量值溯源一直是国内外计量机构的研究重点,目前被广泛认可的尘埃粒子计数器的溯源方法有两种:一是采用参加全国比对的尘埃粒子计数器与待检尘埃粒子计数器进行比对;另一种是通过凝结核粒子计数器溯源至气溶胶静电计,最终溯源至计量基准电流之上。本文将综述尘埃粒子计数器的检测和校准方法以及存在问题。     

光散射尘埃粒子计数器的计量校准规范浅析

光散射尘埃粒子计数器作为监测洁净环境的最主要仪器,已在各领域被广泛应用,其自身性能质量也越来越被关注。近年来,国内外形成了多种光散射尘埃粒子计数器计量校准方法,其相互之间均存在着一定差异,这给仪器生产厂家以及计量机构带来了一定困难。本文简要分析了光散射尘埃粒子计数器相关国内外技术标准的研究现状,并重点对国内目前使用较为广泛的JJF1190和GJB/J5416标准进行了对比分析。     

尘埃粒子计数器校准结果及其应用探讨

本文对尘埃粒子计数器粒子浓度示值误差校准结果的计算进行了讨论,并以制药行业中尘埃粒子计数器的使用为例对尘埃粒子计数器校准结果的应用进行了探讨。     

大流量尘埃粒子计数器校准装置研究

尘埃粒子计数器是用于测量洁净环境中单位体积内尘埃粒子数量和粒径分布的仪器,随着新版GMP实施和大量高等级工业洁净房的应用,大流量的尘埃粒子计数器应用明显增加,针对现有校准装置对大流量尘埃校准时气溶胶雾化流量不足、手动操作易引入人员操作干扰且试验的重现性不佳等缺陷,本课题主要解决传统计数器校准装置存在的不足,提高其校准装置的自动化、信息化水平,解决仪器的校准中复现性差、稳定性不佳的问题,使其满足现在大流量、高稳定性的要求。     

浅谈尘埃粒子计数器校准现状

尘埃粒子计数器主要是用于测量洁净环境中,单位体积内尘埃粒子个数和粒径分布的仪器,现广泛使用于各个行业和部门。由于其种类较多,且在校准过程中出现的问题较为繁杂,本文主要将其校准发展现状进行描述及分析。     

标准尘埃粒子计数器校准方法的可溯源性研究

介绍一种新的标准尘埃粒子计数器校准方法,通过"尘埃粒子计数器—凝结核粒子计数器—气溶胶静电计"的逐级溯源链,将尘埃粒计数器的计数值溯源至电流基准,形成一个完整的溯源体系。结果表明,该方法可以对尘埃粒子计数器量程内粒径的计数效率进行评估,解决各种流量的尘埃粒子计数器的校准问题。     

尘埃粒子计数器的校准方法

尘埃粒子计数器主要用来评定洁净室洁净度等级、检测过滤器的过滤效率及洁净织物的发尘量等。尘埃粒子计数器的量值溯源因其特殊性,存在很大难度,多年来国内外都在致力于尘埃粒子计数器的校准研究。该文就研究以及编写的尘埃粒子计数器国家计量校准规范,来阐述尘埃粒子计数器的校准方法。     

基于信息论的激光尘埃粒子计数器的数学模型

为分析计数器传感器系统各部分对测量结果的影响,从信息的角度出发,在信息论的基础上建立激光尘埃粒子计数器的数学模型.将输入的粒子群的粒径分布看作信源,输出的信号幅度分布看作信宿,将整个计数器看作信道,建立与之对应的数学模型.同时初步探讨了信息论在激光尘埃粒子计数器的应用,利用信息熵来评价信号幅度分布的离散度,用平均互信息来评价计数器对两种不同粒径的粒子的区分度,结果表明当粒子信号幅度分布的信息熵越大时,仪器的性能越差,并用实验进行了验证.这一研究结果为仪器性能的改进提供了指导方向.     

尘埃粒子计数器宏粒子发生装置的研制

尘埃粒子计数器是用于检测评价洁净环境洁净度等级的仪器.目前,尘埃粒子计数器的溯源主要通过全国比对的方式对0.5μm的粒子浓度进行溯源,但制药、医疗器械等行业还普遍关注5.0μm粒径通道的计数准确性,然而5.0μm的粒径通道校准却存在气溶胶发生器浓度难控制、单分散性差的难题.本文针对这一技术难题,研制了一款针对尘埃粒子计...     

尘埃粒子计数器校准过程中常见问题与解决

<正>一、校准中常见问题及分析1.适用范围JJF1190-2008《尘埃粒子计数器校准规范》中已明确其适用于光散射式激光尘埃粒子计数器的校准工作,对其他原理的尘埃粒子计数器并不适用。2.实验环境校准时的温度要求为(20±5)℃,环境温度过高或过低,会影响单分散粒子在尘埃粒子发生装置中的工作状态,从而在一定程度上影响实验结果的准确性;     

浅析尘埃粒子计数器的量值溯源

随着尘埃粒子计数器在各行各业的广泛利用,为保证测量结果的准确可靠,必须对尘埃粒子计数器有效溯源。本文从目前国内外有关的尘埃粒子计数器技术标准出发,详细分析其溯源现状,并探讨进一步的研究方向,供有关计量科研人员参考。     

Construction of an occupational-dust hazard testing platform: An experimental study on the deposition mechanisms

This study aimed to understand the influence of dust concentrations and environmental exposure on the mechanism of dust deposition in the human body following inhalation. Using a self-developed occupational dust hazard testing platform, the particle size and mass of dust in the environment and the dust inhaled by a bionic throat were measured under different conditions. The experimental results showed that an increase in dust concentration in the experimental area resulted in an increase in the size of the dust particles, particularly the absolute value of small-sized dust particles. The range of variation of the particle size of dust inhaled by the bionic throat was less than 25%, and the mass of dust inhaled exhibited a positive linear trend. When the dust concentration was fixed, an increase in the dust exposure time resulted in a gradual decrease in the dust particle size. When the dust exposure time reached 60 s, the particle size of the dust inhaled by the bionic throat remained constant, and the mass of the dust inhaled exhibited an increasing linear trend. With an increase in altitude, the dust concentrations in the experimental area gradually increased, whereas the dust particle size gradually decreased. The mass of dust inhaled by the bionic throat was represented by a quadratic power function. The results provide effective theoretical support for the prevention and control of dust originating from coal mines.     

Evaluation of primary and secondary fugitive dust suppression methods using enclosed water spraying systems at bulk solids handling

To suppress effectively fugitive dust emissions using water spraying systems at bulk solids handling an optimal design of these devices is necessary. The dust suppression mechanism for example at conveyor belt hand over points can be subdivided in a primary and a secondary dust minimization effect. In this case the moistening of the bulk solids is a primary dust minimization effect and the airborne dust capture is a secondary dust minimization effect. In this work the evaluation of both dust minimization effects is carried out. As a first step an experimental investigation of the total and the secondary dust suppression efficiency took place. A model of two separators which are acting in series got used to compare the measured efficiencies and to calculate the primary dust suppression efficiency. The secondary dust suppression effect showed low performance compared to the primary dust suppression efficiency. So it has to be clarified if the streaming situation and the dust concentration situation at the position where the nozzle operates can get improved. Therefore enquiries at different positions in the middle and aside a concentrated particle flow got carried out.The results provide an informative basis how water spraying systems can get improved to suppress fugitive dust emissions at bulk solids handling.     

Estimates of threshold windspeed from particle sizes in blowing snow

Particle size distributions measured in the saltation layer of drifting snow are fitted reasonably well by the two-parameter gamma function. Using these data, the mean particle size 0.25 m above the surface is predicted as a function of windspeed, from the theoretical relationship developed by Budd (1966). Average particle diameters, measured with a photoelectric snow particle counter at a site in southeastern Wyoming, U.S.A., during drifting of moderate intensity, are larger than mean sizes predicted by theory. These experiments provide empirical equations that allow threshold windspeeds for snow transport to be estimated by monitoring an anemometer and particle counter.     

PARTICULATE CONCENTRATION IN AUTOMOBILE PASSENGER COMPARTMENTS

An experimental study of the dust concentration in automobile passenger compartments was conducted to understand how driving conditions and a vehicle's ventilation system can affect cabin air quality. The results of this study are essential for designing appropriate cabin air filters and developing proper test procedures.

The particle size distribution of atmospheric contaminants entering the vehicle's passenger compartment through air registers and in the occupants' breathing zone was measured using an optical particle counter. The concentration and size distribution of aerosol in the cabin was found to be dependent on traffic conditions, road surface, environmental conditions (e.g., weather) and ventilation mode. In all cases over 90% of the particles were smaller than 1 µm. The vehicle's HVAC system (evaporator core) reduces the concentration of aerosol entering the car interior, especially larger particles. Commercial vehicle ventilation filters decrease particle concentrations in a driver's breathing zone for all particle sizes. However, the reduction in the submicron particle range is not sufficient to substantially improve air quality in the passenger cabin.     

Study on mechanism and dynamics of inert powder explosion inhibitor inhibiting aluminum powder explosion

In order to study the suppression performance and action mechanism of inert powder on aluminum powder explosion flame, using the dust explosion flame propagation test system, five kinds of common inert powder and two kinds of aluminum dust with different particle sizes were selected for explosion flame suppression and overpressure suppression experiments. Combined with the thermal characteristic curve of inert powder, the inhibition performance and action mechanism of inert powder on aluminum powder explosion were systematically studied. The results show that the inhibition effect of MPP dry powder on aluminum dust is better than that of NaHCO₃, CaCO₃, Al(OH)₃ and NH₄H₂PO₄; The inhibition mechanism model of inert powder on aluminum powder explosion flame is established, and the action mechanism is analyzed. The oxidation process of aluminum dust with and without MPP dry powder was analyzed by Coats Redfern (C-R) method, and the activation energy and kinetic models of different stages were obtained. The results were verified by Flynn Wall Ozawa (FWO) and Kissinger Akahira Sunose (KAS) methods. The research results can provide a theoretical basis and basis for the explosion suppression design of aluminum dust and the development of explosion suppression powder.     

褐煤煤尘爆炸火焰传播特性及燃烧热分解机理研究

煤尘爆炸是矿井安全开采的主要危险源之一。以褐煤煤尘为研究对象,探究煤尘粒径对煤尘火焰传播过程的影响。用高速摄影装置记录火焰的传播过程,进而分析不同粒径下煤尘爆炸火焰传播的高度和速度。为进一步分析煤尘燃烧过程中的化学反应机理,借助反应分子动力学方法对煤分子燃烧中的初始热分解过程进行了模拟。研究结果表明:爆炸火焰传播高度呈先增加、后稳定的趋势,传播速度呈先增大、后减小的趋势;随着煤尘粒径的减小,火焰传播高度和传播速度均呈增大的趋势;当煤尘粒径为10.5 μm时,火焰传播高度和传播速度的峰值分别为623 mm和4.3 m/s;煤尘热分解主要产物为H₂、H₂O、CO₂和CH₂O,这些产物进一步与氧气的结合会促进煤尘燃烧和火焰传播过程,使得整个体系燃速加快。为煤尘热分解和燃烧提供了较为充分的数据基础。     

声凝并中颗粒间相互作用研究进展

声凝并是细颗粒物(PM2.5)排放控制的重要技术途径,其通过外加声场作用促进PM2.5发生碰撞凝并,使得颗粒数目减少、粒径增大,从而提高后续除尘装置的效率。对声凝并中颗粒间的相互作用机理,包括同向相互作用、声尾流效应、互辐射压力效应、互散射效应的相关研究进行总结和评述,结合声凝并技术在PM2.5排放控制中的应用,指出已有研究在理论模型和实验观测上存在的问题,进而提出今后的研究应在实验方法上进行创新,发展出能够跟踪微米和亚微米尺度PM2.5颗粒或颗粒团相互作用过程细节信息的实验手段,为理论模型的实验验证提供数据支撑;同时应进一步发展理论模型,从而在模型验证的基础上,充分发挥数值模拟的优势,全面识别声凝并中颗粒间相互作用的动力学行为。