04 Fakultät Energie-, Verfahrens- und Biotechnik
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/5
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Item Open Access Feasibility study on the use of NO2 and PM2.5 sensors for exposure assessment and indoor source apportionment at fixed locations(2024) Chacón-Mateos, Miriam; Remy, Erika; Liebers, Uta; Heimann, Frank; Witt, Christian; Vogt, UlrichRecent advances in sensor technology for air pollution monitoring open new possibilities in the field of environmental epidemiology. The low spatial resolution of fixed outdoor measurement stations and modelling uncertainties currently limit the understanding of personal exposure. In this context, air quality sensor systems (AQSSs) offer significant potential to enhance personal exposure assessment. A pilot study was conducted to investigate the feasibility of the NO2 sensor model B43F and the particulate matter (PM) sensor model OPC-R1, both from Alphasense (UK), for use in epidemiological studies. Seven patients with chronic obstructive pulmonary disease (COPD) or asthma had built-for-purpose sensor systems placed inside and outside of their homes at fixed locations for one month. Participants documented their indoor activities, presence in the house, window status, and symptom severity and performed a peak expiratory flow test. The potential inhaled doses of PM2.5 and NO2 were calculated using different data sources such as outdoor data from air quality monitoring stations, indoor data from AQSSs, and generic inhalation rates (IR) or activity-specific IR. Moreover, the relation between indoor and outdoor air quality obtained with AQSSs, an indoor source apportionment study, and an evaluation of the suitability of the AQSS data for studying the relationship between air quality and health were investigated. The results highlight the value of the sensor data and the importance of monitoring indoor air quality and activity patterns to avoid exposure misclassification. The use of AQSSs at fixed locations shows promise for larger-scale and/or long-term epidemiological studies.Item Open Access Meteorological and air quality measurements in a city region with complex terrain : influence of meteorological phenomena on urban climate(2023) Samad, Abdul; Kiseleva, Olga; Holst, Christopher Claus; Wegener, Robert; Kossmann, Meinolf; Meusel, Gregor; Fiehn, Alina; Erbertseder, Thilo; Becker, Ralf; Roiger, Anke; Stanislawsky, Peter; Klemp, Dieter; Emeis, Stefan; Kalthoff, Norbert; Vogt, UlrichItem Open Access Novel metal mesh filter using water-based regeneration for small-scale biomass boilers(2020) Baumgarten, Björn; Grammer, Peter; Ehard, Ferdinand; Winkel, Oskar; Vogt, Ulrich; Baumbach, Günter; Scheffknecht, Günter; Thorwarth, HaraldParticulate matter emissions are a key issue of modern biomass boilers. A novel gas cleaning method using a metal mesh filter combined with water-based cleaning was developed and tested. The filter was tested batch-wise. Flue gas of a commercial 50-kW boiler was filtered until a pressure drop of 2000 Pa was reached. Afterwards, the filter was regenerated. The initial prototype used ultrasound in order to remove the filter cake from the filter candles. Regeneration was complete and, even after boiler malfunctions producing tar, the filter cake could still be removed. Given the good results, a second cleaning mode, flushing the filter candles with water, was tested. The results were as good as with ultrasonic cleaning. Peak mass collection efficiency was very high with 98 ± 2% (burning wood pellets). However, directly after cleaning, the first layer of filter cake has to be developed. In this initial phase, collection efficiency is low. Service time until maximum pressure drop was reached depended on the gas velocity. Using pellets as fuel, at a gas velocity of 66.6 m/h, 12-h service time was reached and 4.1 g dust was collected per square meter filter surface, while at 33.3 m/h, service time increased to 55 h and collected dust to 13.9 g/m2. Using low-quality wood chips, the raw gas dust loading was much higher but also the maximum loading of the filter was higher with 13.3 to 28.9 g dust separated per square meter. Still, the service time decreased to 3.4 respective 38 h. Peak collection efficiency increased to 99.5 ± 0.8%. The overall collection efficiency including the buildup of the filter cake depends on the gas velocity and fuel. It ranges from 74 ± 4 to 91 ± 1%. The feasibility of the filter concept could be proven, and further development towards a commercial application is in progress. Metal mesh filters with countercurrent cleaning showed a high potential given their simple and robust design, as well as high collection efficiency.Item Open Access Evaluation of a metal mesh filter prototype with wet regeneration(2021) Baumgarten, Björn; Grammer, Peter; Ehard, Ferdinand; Winkel, Oskar; Vogt, Ulrich; Baumbach, Günter; Scheffknecht, Günter; Thorwarth, HaraldWood combustion is a major part of the current efforts to reduce CO2 emissions. However, wood combustion leads to emissions of other pollutants like fine particulate matter. A new option to reduce particulate matter emissions is a metal mesh filter with counter current flushing. An automatic prototype was tested under realistic conditions including starts and stops of the boiler. For regeneration, the filter was flushed using water in opposite flow direction. The water was recycled multiple times to limit water consumption. The results are very promising. Regeneration was successful and no signs of decay could be observed over 419.5 h of operation and 234 regenerations. The filter can be operated during all phases of boiler operation, which is a major step forward compared to alternative secondary measures. Separation efficiency was high with 80-86%, even though the filter showed internal leakage, which reduced the separation efficiency. Additionally, waste products were examined. About 1000 l wastewater can be expected to be produced every month, which could be disposed using the communal waste water system, given the low heavy metal loading. A part of the fine particulate matter is unsoluble and has to be removed from the regeneration water before reuse. The unsoluble fraction contains the majority of heavy metals and has to be disposed as fly ash or used for urban mining. Generally spoken, the metal mesh filter is a new, promising option which can overcome limitations of current secondary measures without increasing costs given its simple and robust construction.Item Open Access Calibration method for particulate matter low-cost sensors used in ambient air quality monitoring and research(2021) Venkatraman Jagatha, Janani; Klausnitzer, André; Chacón-Mateos, Miriam; Laquai, Bernd; Nieuwkoop, Evert; Mark, Peter van der; Vogt, Ulrich; Schneider, ChristophOver the last decade, manufacturers have come forth with cost-effective sensors for measuring ambient and indoor particulate matter concentration. What these sensors make up for in cost efficiency, they lack in reliability of the measured data due to their sensitivities to temperature and relative humidity. These weaknesses are especially evident when it comes to portable or mobile measurement setups. In recent years many studies have been conducted to assess the possibilities and limitations of these sensors, however mostly restricted to stationary measurements. This study reviews the published literature until 2020 on cost-effective sensors, summarizes the recommendations of experts in the field based on their experiences, and outlines the quantile-mapping methodology to calibrate low-cost sensors in mobile applications. Compared to the commonly used linear regression method, quantile mapping retains the spatial characteristics of the measurements, although a common correction factor cannot be determined. We conclude that quantile mapping can be a useful calibration methodology for mobile measurements given a well-elaborated measurement plan assures providing the necessary data.