A monodisperse-aerosol generation system： Design, fabrication and performance

Monodisperse aerosols are essential in many applications, such as filter testing, aerosol instrument calibration, and experiments for validating models. This paper describes the design principle, construction, and performance of a monodisperse-aerosol generation system that comprises an atomizer, virtual impactor, microcontroller-based isokinetic probe, wind tunnel, and velocity measurement device. The size distribution of the produced monodisperse aerosols was determined by an optical particle counter. The effects of atomizer characteristics, the rates of minor and major flow, and solution criteria were investigated. It was found that all these parameters affect the generation of monodisperse aerosol. Finally, the expected geometric standard deviation （〈1.25） of monodisperse aerosol particles was obtained with the most suitable atomizer for 10% oleic acid in ethyl alcohol solution with 5%-15% minor flow, where the ratio between the nozzle-to-probe distance and acceleration-nozzle-exit diameter was 0.66. The con- structed monodisperse-aerosol-generation system can be used for instrumental calibration and aerosol research.

Key Technologies for Preparing Nanoparticles of Hydrogen Storage Material by Combining Ball Milling with Aerosol Generation

The developing trend of vehicle is electrical vehicle in future, and fuel cell will become the one of the main batteries of electrical vehicle because of its the prominent properties. The one of current obstacle for fuel cell in popularization and applications is lacking of excellent performance hydrogen storage materials and advanced technologies of preparing nanoparticles for hydrogen storage materials. The principles, typical classifications and characteristics of chemically and physically preparing nanoparticles for hydrogen storage materials are briefly introduced. And it predicts that physical method is going to be the major developing direction for nanoparticles for hydrogen storage material fabrication. The principle, the system composition ＆ characteristics of method by means of combining ball milling with aerosol generation preparing nanoparticles for hydrogen storage materials are expounded. The ball milling process for hydrogen storage material is needed to conduct effective cooling process, and the lower cooling temperature has better milling results. The cooling media for ball milling include room temperature water, ice water, pure ethanol with dry ice and liquid nitrogen. The proper level of vacuum in canister is significant for injecting aerosol particles during the ball milling. In order to maximize the friction force, it is better to design multi-level stirring rod and the profile of stirring rod with large contact area, therefor stirring rod with cylinder has less grinding effect than with ring profile. The more stirring rod with more layers will obtain higher stirring efficiency. The distance between each layer of branches is 2.5 times larger than diameter of the ball. The simulation results show that the average speed has 120% increases from 400 rpm to 800 rpm. Based on the kinetic energy equation, it is obtained that there is 350% increase in energy from 400 r/min to 800 r/min. The higher stirring speed will generate the finer material. And the discussion of this article provides a favorable basis of preparing nanoparticles for hydrogen storage materials in fuel cell vehicle.

Design and Characterization of an Aerosol Test Chamber for Emergency Response Patient Contamination Control Simulation and Research

Contaminated or infected patients present a risk of cross-contamination for emergency responders, attending medical personnel and medical facilities as they enter a treatment facility. The controlled conditions of an aerosol test chamber are required to examine factors of contamination, decontamination, and cross-contamination. This study presents the design, construction, and a method for characterizing an aerosol test chamber for a full-sized manikin on a standard North Atlantic Treaty Organization litter. The methodology combined air velocity measurements, aerosol particle counts and size distributions, and computational fluid dynamics modeling to describe the chamber’s performance in three dimensions. This detailed characterization facilitates future experimental design by predicting chamber performance for a variety of patient-focused research.

Theoretical Study on Efficiency of Anti-explosion and Fireproof Agents

Multi-protection is a principle in security management, and the use of anti-explosion and fireproof agents is a crucial part of it. In this paper, the properties of nano-oxide particles in the field of anti-explosion and fireproof were analyzed. The sedimentation velocity of nanometer particles was calculated. CH4 was taken as an example, and its combustion mechanism of the initial stages was concluded. The effects of 15 oxides on molecular energies of the reaction system were calculated with program Hyperchem 6, and the possible contact manner between radi- cals and oxides was got. It was concluded that oxides, such as ZrO2, could combine with radicals, and thus prevent the combustion reaction. It was found that the nano-ZrO2 eruptively generated aerosol is superior to other counterparts in serving as the anti-explosion and fireproof agent, and therefore, will play an increasingly important role in the security management.