The Experimental Investigations of Dielectric Barrier Discharge and Pulse Corona Discharge in Air Cleaning

The dielectric barrier discharge (DBD) and pulse corona discharge(PCD) plasma generator was used to remove NH3, H2S, C7H8 etc. from atmosphere. The principle and characteristic of the two ways was discussed in the article. The test shows the result of PCD is better than that of DBD.

Warp Air Clean产品特征及其减排效果研究

传统机动车研究假设发动机进气为新鲜空气,但在实际道路环境中,大量污染物会改变发动机的进气质量,从而影响燃烧。Warp Air Clean(WAC)技术通过在硅橡胶中填充碳颗粒,利用碳颗粒的导电性去除进气中的带电粒子,从而达到净化进气、改善燃烧进而减少尾气排放的目的。本研究多种材料检测技术,研究了WAC材料的基本特征,并基于实际道路测试及台架测试,验证了该技术的减排效果。研究结果表明,WAC技术能够有效地减少机动车的THC、CO、NOx和颗粒物排放。

不同技术路线Warp Air Clean材料对机动车尾气减排效果研究

传统机动车尾气减排技术经过长期发展,取得了较好效果,但在短期难以获得更大的突破。Warp Air Clean(WAC)技术通过对发动机的进气进行净化,提高发动机内燃烧效率,从而减少尾气排放,是解决机动车尾气排放的新途径。本研究对比了四种不同合成方案WAC材料的减排效果,为该技术的进一步完善优化提供了基础。研究发现:采用加成型硅橡胶合成方案的合成材料效果最好,在怠速与高怠速工况下均能有效降低机动车排放的CO、THC和NO。

Key Technology and Experimental Results of the Clean Air Heated Facility for Supersonic Combustion

The scramjet, which is the propulsion of hypersonic vehicle, has become the focus in many military developed countries. The ground tests play an important role in the research of scramjet. There is defect of test medium contamination （the thermochemical characteristic of the ground test medium is different from that of the flight medium） in existing ground test facilities for scramjet combustor experiment. To solve the problem of test medium contamination, the first clean air heated facility of China for scramjet combustor experiment is designed. The key technology of designing the clean air heated facility is summarized. By using bypass duct, combustor model is protected from high temperature. To reduce the switching time between main duct and bypass duct, solenoid valve and water-cooled system were used. Having centrosymmetric structure, the heat radiating area of the facility and heat loss of the facility are much lower than others. Clean air heated facility is adopted to conduct experiment, which is the first experiment of China in clean air inflow, research on hydrogen-fueled and ethylene-fueled ignition and combustion for scramjet combustor at different equivalence ratio. Successful ignition and sustained combustion of hydrogen has been achieved. Successful ethylene ignition and sustained main stream combustion is achieved with normal fuel injection and taking hydrogen as pilot flame. Experiment result shows that the wall pressure of combustor model rises when the equivalence ratio of hydrogen rises. As the wall pressure of combustor model rises, the pressure disturbance influences the shock train in the upstream.

Performance and Effectiveness of Portable Air Cleaners in an Office Room： An Experimental Study

Nowadays, many people work in an office environment. Air pollutants, including particles and gases, are generated by humans and by different devices that are used in offices. Pollutants can also enter an office room with the air supplied from outdoors. It has been established that air pollutants have adverse health effects on human body. Air cleaning devices are commonly marketed as being beneficial for the health by removing air pollutants and consequently improving indoor air quality. The performance of five air cleaning technologies was tested in order to determine the generation of ozone and particles in an office room. The particle removal effectiveness of the technologies was also determined in order to clarify their ability to remove UFPs （ultrafine particles） in the office room. The tested five air cleaning technologies are non-thermal plasma, corona discharge ionizer, portable air purifier, electrostatic fibrous filter and three-dimensional fibrous filter. The interior surfaces of the office room emit low levels of volatile organic compounds, since the office room has not been refurbished for about two decades. The results showed that the particle removal effectiveness of the technologies was ranged between 0.2 and 0.45 for the office room. The three technologies using/generating ozone significantly increased the ozone level in the office room. However, no increase of the UFP concentration was detected.

Clean Air Act:Awareness and Opinions Among Marine Engineering Students

This study aims to determine the awareness and opinions on Clean Air Act among marine engineering students at maritime university,specifically,John B.Lacson Foundation Maritime University-Molo,Iloilo City,Philippines.The participants of this study were 30 marine engineering students of the maritime university,especially JBLFMU-Molo for school year 2014-2015.Participants of the study were enrolled at the College of Maritime Education,JBLFMU-Molo,Iloilo City,Philippines.The researchers employed quantitative research design.The respondents’comments,suggestions,observations,and remarks on the perceived awareness and opinions on Clean Air Act were captured in this study.After gathering the qualitative information,the researchers classified and categorized the write-ups of the respondents into different categories.The results reveal that the participants of the present study were aware of the Clean Air Act as an entire group and when classified according to different categories.Most of the participants said that Clean Air Act protects the environment,followed by the participants who said that Clean Air Act can prevent air pollution.Next,in rank,the participants who said“it is good because you can go everywhere to inhale fresh air,followed by participants who said Clean Air Act can reduce the things that can harm the ozone layer,the last participants said that they never heard of Clean Air Act.

The 2022 report of synergetic roadmap on carbon neutrality and clean air for China:Accelerating transition in key sectors

China is now confronting the intertwined challenges of air pollution and climate change.Given the high synergies between air pollution abatement and climate change mitigation,the Chinese government is actively promoting synergetic control of these two issues.The Synergetic Roadmap project was launched in 2021 to track and analyze the progress of synergetic control in China by developing and monitoring key indicators.The Synergetic Roadmap 2022 report is the first annual update,featuring 20 indicators across five aspects:synergetic governance system and practices,progress in structural transition,air pollution and associated weather-climate interactions,sources,sinks,and mitigation pathway of atmospheric composition,and health impacts and benefits of coordinated control.Compared to the comprehensive review presented in the 2021 report,the Synergetic Roadmap 2022 report places particular emphasis on progress in 2021 with highlights on actions in key sectors and the relevant milestones.These milestones include the proportion of non-fossil power generation capacity surpassing coal-fired capacity for the first time,a decline in the production of crude steel and cement after years of growth,and the surging penetration of electric vehicles.Additionally,in 2022,China issued the first national policy that synergizes abatements of pollution and carbon emissions,marking a new era for China's pollution-carbon co-control.These changes highlight China's efforts to reshape its energy,economic,and transportation structures to meet the demand for synergetic control and sustainable development.Consequently,the country has witnessed a slowdown in carbon emission growth,improved air quality,and increased health benefits in recent years.

Benefit of aerosol reduction to winter wheat during China's clean air action:A case study of Henan Province

A strongly declining aerosol radiative effect has been observed in China since 2013 after implementing the clean air action,yet its impact on wheat(Triticum aestivum L.)production remains unclear.We use satellite measures and a biophysical crop model to assess the impact of aerosol-induced radiative perturbations on winter wheat production in the agricultural belt of Henan province from 2013 to 2018.After calibrating parameters with the extended Fourier Amplitude Sensitivity Test(EFAST)and the generalized likelihood uncertainty estimation(GLUE)method,the DSSAT CERES-Wheat model was able to simulate crop biomass and yield more accurately.We found that the aerosol negatively impacted wheat biomass by 21.87%and yield by 22.48%from 2006 to 2018,and the biomass effects from planting to anthesis were more significant compared to anthesis to maturity.Due to the strict clean air action,under all-sky conditions,the surface solar shortwave radiation(SSR)in 2018 increased by about 7.08%over 2006-2013 during the wheat growing seasons.As a result of the improvement of crop photosynthesis,winter wheat biomass and yield increased by an average of 5.46%and 2.9%,respectively.Our findings show that crop carbon uptake and yield will benefit from the clean air action in China,helping to ensure national food and health security.

Reduction in polycyclic aromatic hydrocarbon exposure in Beijing following China’s clean air actions

Exposure to polycyclic aromatic hydrocarbons(PAHs)in the Chinese population was among the highest globally and associated with various adverse effects.This study examines the impact of China’s twophase clean air initiatives,namely the Air Pollution Prevention and Control Action Plan(APPCAP)in2013–2017 and the Blue-Sky Defense War(BSDW)in 2018–2020,on PAH levels and human exposures in Beijing.To evaluate the effects of APPCAP,we measured 16 PAHs in 287 PM_(2.5)samples collected in Beijing and 9 PAH metabolites in 358 urine samples obtained from 54 individuals who traveled from Los Angeles to Beijing between 2014 and 2018.The concentration of PM_(2.5)-bound benzo[a]pyrene equivalents(BaPeq)decreased by 88.5%in 2014–2018 due to reduced traffic,coal,and biomass emissions.PAH metabolite concentrations in travelers’urine decreased by 52.3%in Beijing,correlated with changes in PM_(2.5)and NO2levels.In contrast,no significant changes were observed in Los Angeles.To evaluate BSDW’s effects,we collected 123 additional PM_(2.5)samples for PAH measurements in 2019–2021.We observed sustained reductions in BaPeq concentrations attributable to reductions in coal and biomass emissions during the BSDW phase,but those from traffic sources remained unchanged.After accounting for meteorological factors,China’s two-phase clean air initiatives jointly reduced Beijing’s PM_(2.5)-bound BaPeq concentrations by 96.6%from 2014 to 2021.These findings provide compelling evidence for the effectiveness of China’s clean air actions in mitigating population exposure to PAHs in Beijing.

Aerosol Filtration Application Using Fibrous Media—An Industrial Perspective

Filtration of aerosol particles using non-woven fibrous media is a common practice for air cleaning. It has found wide applications in industries and our daily lives. This paper overviews some of these applications and provides an industrial perspective. It starts from discussing aerosol filtration theory, followed by a brief review on the advancement of filtration media. After that, filtration applications in respiratory protection, dust collection, and engine in-take air cleaning are elaborated. These are the areas that the author sees as the typical needed ones in China's fast pace economical development endeavor, where air filtration enables the protection of human health, environment and equipment for sustainability.

Synergetic roadmap of carbon neutrality and clean air for China

It is well recognized that carbon dioxide and air pollutants share similar emission sources so that synergetic policies on climate change mitigation and air pollution control can lead to remarkable co-benefits on greenhouse gas reduction,air quality improvement,and improved health.In the context of carbon peak,carbon neutrality,and clean air policies,this perspective tracks and analyzes the process of the synergetic governance of air pollution and climate change in China by developing and monitoring 18 indicators.The 18 indicators cover the following five aspects:air pollution and associated weather-climate conditions,progress in structural transition,sources,inks,and mitigation pathway of atmospheric composition,health impacts and benefits of coordinated control,and synergetic governance system and practices.By tracking the progress in each indicator,this perspective presents the major accomplishment of coordinated control,identifies the emerging challenges toward the synergetic governance,and provides policy recommendations for designing a synergetic roadmap of Carbon Neutrality and Clean Air for China.

Cleaning Up the Air

The Minister of Environmental Protection pushes for cleaner communities in China Environmental Protection

Quantification of emission reduction potentials of primary air pollutants from residential solid fuel combustion by adopting cleaner fuels in China

Residential low efficient fuel burning is a major source of many air pollutants produced during incomplete combustions, and household air pollution has been identified as one of the top environmental risk factors. Here we compiled literature-reported emission factors of pollutants including carbon monoxide（CO）, total suspended particles（TSPs）, PM2.5, organic carbon（OC）,elemental carbon（EC） and polycyclic aromatic hydrocarbons（PAHs） for different household energy sources, and quantified the potential for emission reduction by clean fuel adoption. The burning of crop straws, firewood and coal chunks in residential stoves had high emissions per unit fuel mass but lower thermal efficiencies, resulting in high levels of pollution emissions per unit of useful energy, whereas pelletized biofuels and coal briquettes had lower pollutant emissions and higher thermal efficiencies. Briquetting coal may lead to 82%–88% CO, 74%–99%TSP, 73%–76% PM2.5, 64%–98% OC, 92%–99% EC and 80%–83% PAH reductions compared to raw chunk coal. Biomass pelletizing technology would achieve 88%–97% CO, 73%–87% TSP, 79%–88%PM2.5, 94%–96% OC, 91%–99% EC and 63%–96% PAH reduction compared to biomass burning. The adoption of gas fuels（i.e., liquid petroleum gas, natural gas） would achieve significant pollutant reduction, nearly 96% for targeted pollutants. The reduction is related not only to fuel change, but also to the usage of high efficiency stoves.

A new pin-to-plate corona discharger with clean air protection for particulate matter removal

High concentration particulate matter(PM)has been a serious environmental problem in China and other devel-oping countries.Electrostatic-based purification technology is a method to remove airborne particles,and can reduce the energy consumption of ventilation fans in buildings because of its low pressure drop.In this study,we developed a new pin-to-plate corona discharger with particle-free external air protection to prevent particles polluting the surface of discharge pins.By using an optical microscope,we observed a certain number of parti-cles deposited on the non-protected(exposed pins)and few particles deposited on the protected pins after they operating for 3 weeks.We experimentally studied the long-term performances of the exposed and protected pins in single-pass PM removal efficiency and ozone production.The results showed that the protected pins produce less ozone and have higher breakdown voltage than the exposed pins.Experimental results indicated that the im-proved pin-to-plate corona discharger has better long-term performance and is safer than the exposed one.The results of the research can give an understanding of how to improve electrostatic-based purification technologies toward stable discharging for high removal efficiency of particles.

Research on Relation between Air Anions and Environment in Shanghai City

By measuring the concentration of air anions, thermal-temperature, tree-coverage and bio-diversity in major city greenbelt in Shanghai, this paper analyzed thecorrelativity between air cleaning index and its influential factorsof thesecity greenbelt, and found that less than 60% of parks’ concentration of air inions anions arrived at the general level. There is negative correlation between CI(air clean index) and thermal- temperature, and there is negative correlation between CIand bio-diversity too. Thereis Positivecorrelation between CI and tree-coverage.

Experimental characterization of the removal efficiency and energy effectiveness of central air cleaners

This study assessed six commercially available in-duct air cleaning devices which are designed to be mounted in the central ventilation system of offices or commercial buildings.The selected devices use different air cleaning technologies:mechanical filtration,electrostatic precipitation,gas filtration,ionization/cold plasma,photocatalytic oxidation(PCO)and catalysis under UV light.They were tested against particles,a mixture of volatile organic compounds containing acetone,acetaldehyde,toluene,heptane and formaldehyde,and two bio-contaminants:Aspergillus brasiliensis(fungus)and Staphylococcus epidermidis(bacteria).Two different test rigs were used.The single pass efficiency of each device was determined for three airflow rates,corresponding to face velocities ranging from 0.9 to 2.7 m/s,and two sets of temperature and humidity that are representative of indoor air conditions in wintertime and summertime.The concentration of the chal-lenge volatile organic compounds was also varied in the 30 to 100μg/m^(3)range as a way to characterize their influence on efficiency at realistic concentration levels for non-industrial buildings.Measurements of ozone and formaldehyde concentration downstream of the air cleaners were carried out to determine the emission rate of by-products into the air stream.Finally,the energy issue was addressed by measuring the electric power drawn and pressure loss of the devices.The results showed that two devices,namely a radiant catalytic ionizer and a plasma ionizer,had a very low single pass efficiency against all the challenge pollutants.The association of the plasma ionizer and the electrostatic precipitator did not produce a synergetic effect between the two technologies either,contrary to what their manufacturer claims.Finally,three of the six devices tested were effective in terms of pollutant removal,but only two had an acceptable energy effectiveness in view of their use in low or zero energy buildings.Their energy effectiveness ranged from a few thousand m^(3)/kWh for VOCs at the highest airflow rate(3600 m^(3)/h),to more than 60000 m^(3)/kWh for particles and bio-contaminants at 1200 or 1600 m^(3)/h.These results are at least one order of magnitude higher than the majority of stand-alone air cleaners.Moreover,they suggest that optimal IAQ and energy conditions can be achieved if variable air volume control methods are used to maintain indoor temperature and humidity.