The internal combustion engine requires clean air in order to operate without problems the entire service life. The air filter acts as a barrier between the ambient air ridden with particulate matter, and the sensitive interior of the engine. Several factors affect the air filter performance, such as pressure drop, efficiency, and dust holding capacity. Many external factors affect the air filter too, such as driving style, engine type, if the car is equipped with hybrid propulsion et cetera. The scope for this thesis work aims to extend the knowledge of air filtration for the customer, in this case, Volvo Cars. A comprehensive literature study along with benchmarking of competitors acts as a foundational approach. Regarding air filter service life, three parameters are identified as the most significant: dust holding capacity, efficiency and pressure drop over the filter element. Reverse engineering shows some competitor design decisions. A model of estimating air consumption is developed using a data-driven approach with real-world driving data as a basis. The model shows how much the actual air consumption varies between different markets and various engines. As a result, the service lifetime of air filters in certain cars with certain engines may be extended or allow for a smaller filter size for the same service lifetime.

Scania has identified a problem among certain costumers in very dusty environments. The air filters for their truck’s climate system need extensive maintenance, replacement or manual cleaning, because of dust frequently loading up the filters. In this thesis the problem has been analyzed in order to find a solution. The process was initiated by the usage of the black box method, where needed transformations were found, resulting in three needed technical systems. Thereafter, brainstorming was used to find concepts for each technical system. Concepts were compared and ranked against each other. For the most critical of the three systems, the cleaning action, prototypes were built of the four highest ranked concepts. These prototypes were then used to compare the performance between the concepts. The selected filter cleaning device consists of a method to analyze filter blockage, alert the driver when cleaning is needed and a system to clean the filter for the Scania climate system. The system consists of a pressure sensor used to measuring filter blockage, an air pulse system which cleans the filter and a controller unit to control the cleaning cycle and to inform the driver. The air pulse system has two main parts, a pulse valve and an air tank. The pulse valve is used for releasing the air accumulated in the air tank. The complete system is supplied with 8.5 bar from the internal air pressure system in the truck and a 24 V power supply, also located in the truck. A suggestion on how a final implementation can be done has been developed, with a minimized number of variants and modifications of parts already in production. A proof of concept was built and mounted in a truck to validate the complete system. Numbers on cleaning performance and sound levels have been produced. The proof of concept manages to remove the restriction created from dust by approximately 50 %. Aside from developing a suitable filter cleaning device, figures on when the filter needs to be cleaned have been identified. To keep a good working environment within the cab a pressure drop over the filter of 936 Pa is recommended as a point of cleaning. This is to maintain the needed airflow of at least 123 m3/h with two persons seated in the cab to not exceed regulated levels of CO2 within the truck cab.

<p>Aerosols are solid or liquid particles that span in size from a few nanometers to tens of micrometers. They are important in both outdoor and indoor environments due to their impact on climate and human health. Many aerosol processes of interest to the environment, health, and filtration are strongly size-dependent. Aerosol particle size distributions (PSDs) provide a basis to better understand outdoor and indoor air pollution sources, evaluate human exposure to air pollution, and aerosol deposition in the human respiratory tract and filters in building ventilation systems. Monitoring the temporal evolution of aerosol PSDs enable for characterization of dynamic aerosol transport and transformation processes, such as direct emissions, nucleation, condensation, coagulation, resuspension, deposition, and filtration. This thesis presents three studies on the PSDs of: (i.) urban aerosols in cities around the world in order to identify geographical trends in the shape and magnitude of PSDs and to frame future research needs for PSD observations at a global-scale, (ii.) synthesized salt particles from a novel thermal aerosol generator to evaluate its suitability for air filter testing, and (iii.) indoor biological particulate matter (<i>bio</i>PM) to characterize transient inhalation exposures of infants and adults to resuspended <i>bio</i>PM from carpet dust induced by crawling and walking.</p> <p>First, this thesis presents the current state-of-knowledge of urban aerosol PSDs by critically analyzing <i>n</i>=793 urban aerosol PSD observations made between 1998 to 2017 in <i>n</i>=125 cities in <i>n</i>=51 countries across the following regions of the world: Africa (AF), Central, South, and Southeast Asia (CSSA), East Asia (EA), Europe (EU), Latin America (LA), North America, Australia, and New Zealand (NAAN), and West Asia (WA). Prominent geographical variations in the shape and magnitude of urban aerosol number and mass PSDs were identified and significant variations in number PSDs were found between cities in EU and NAAN with those in CSSA and EA. Most PSD observations published in the literature are short-term, with only 14% providing data for longer than six months. There is a paucity of PSDs measured in AF, CSSA, LA, and WA, demonstrating the need for long-term aerosol measurements across wide size ranges in many cities around the globe. Inter-region variations in PSDs have important implications for population exposure, driving large differences in the urban aerosol inhaled deposited dose rate received in each region of the human respiratory system. Similarly, inter-region variations in the shape of PSDs impact the penetration of urban aerosols through filters in building ventilation systems, which serve as an important interface between the outdoor and indoor atmospheres. The results of this critical review demonstrate that global initiatives are urgently needed to develop infrastructure for routine and long-term monitoring of urban aerosol PSDs spanning the nucleation to coarse modes.</p> <p>Second, this thesis evaluates a newly designed commercially available thermal aerosol generator for ageing air filters in building heating, ventilation, and air-conditioning (HVAC) systems. The physical characteristics of the synthesized salt aerosol (NaCl and KCl) under different generator operational conditions were evaluated. The shape of the number and mass PSD output of the thermal aerosol generator are similar to those found in outdoor (urban) and indoor air and can be modulated by varying the rate at which the salt stick is fed into the flame. The morphology of the NaCl and KCl particles varied with size, with compact spherical or cubic structures observed below 100 nm and agglomerates observed above 100 nm. The thermal aerosol generator is a cost-effective technique for rapid ageing of HVAC filters with a PSD that more accurately represents, compared to conventional loading dusts, what filters encounter in real HVAC installations.</p> <p>Lastly, this thesis characterizes infant and adult inhalation exposures and respiratory tract deposited dose rates of resuspended <i>bio</i>PM from carpets. Chamber experiments were conducted with a robotic crawling infant and an adult performing a walking sequence. Breathing zone (BZ) size distributions of resuspended fluorescent biological aerosol particles (FBAPs), a <i>bio</i>PM proxy, were monitored in real-time. FBAP exposures were highly transient during periods of locomotion. Both crawling and walking delivered a significant number of resuspended FBAPs to the BZ, with concentrations ranging from 0.5-2 cm^-3. Infants and adults are primarily exposed to a unimodal FBAP size distribution between 2 and 6 μm, with infants receiving greater exposures to super-10 μm FBAPs. In just one minute of crawling or walking, 10²-10³ resuspended FBAPs can deposit in the respiratory tract, with an infant receiving much of their respiratory tract deposited dose in their lower airways. Per kg body mass, an infant will receive nearly four times greater respiratory tract deposited dose of resuspended FBAPs compared to an adult.</p>

Original equipment manufacturers (OEMs) spend plenty of resources in developing products and establishing a profitable market. This includes time-consuming investigations, costly research and development processes, as well as a great deal of risk-taking. In comparison, certain companies specialise in fitting aftermarket merchandise to established markets of products. These companies copy existing aftermarket products as they supply the consumer an alternative that is often cheaper. These are regarded as ‘will-fitters’. Not only do will-fitters act within the market without the need for a lengthy R&amp;D process, or exposure to high risk, but they also seize market share and thereby compromise OEM part sales. Will-fitters pose a concrete competitive threat to an automotive OEM in the aftermarket. The aftermarket is considered highly lucrative, as profitability is relatively high when compared to the car sales market. As will-fitters are active in the market, spare part market share is lost and pieces of a highly profitable market are seized by such competitors. This study investigates relevant OEM competition barriers for will-fitter deterrence and analyses the effects of implementing these barriers. The findings are based upon a case study performed at an automotive OEM, i.e. Volvo Cars. The case focuses on the OEM’s engine air filter, which is currently highly exposed to competition from alternative suppliers. Through combining theory regarding product development and entry barriers along with empirical findings at the case company, the study concludes six competition barriers that are relevant for the OEM as it faces will-fitters. These barriers are: patenting a utility, increasing the level of product complexity, raising the necessary financial investments, delivering additional value offerings, obtaining a strong customer value perception, and pricing competitively. The study concludes each of the barriers’ potency in competition deterrence and discusses the effects of implementing those barriers on the products’ underlying costs. Finally, it is concluded that these barriers could be implemented in order to deter competition. However, none of the discussed competition barriers has shown to yield complete market dominance for the OEM, i.e. a market without competitors. Rather, an effect in the form of decreasing the amount of competitors has been noted. Admittedly, reducing the sheer quantity of active market players seems favourableto the OEM, but a direct correlation with increased market share cannot be concluded. / Tillverkare av originalutrustning (Original Equipment Manufacturer, OEM) spenderar stora mängder resurser för att utveckla produkter och etablera vinstdrivande marknader. Detta kräver ett stort risktagande då tid och kostsam utveckling utförs utan garanterade intäkter. Till skillnad från OEM-företagen finns företag som enbart fokuserar på att producera eftermarknadsprodukter till redan etablerade marknader. Dessa företag, benämnda “will-fitters”, kopierar existerande eftermarknadsprodukter och erbjuder kunden ett, oftast, billigare alternativ. Will-fitters affärsmodell utgörs därmed av att agera inom etablerade marknader vilket medför drastiskt minskade produktutvecklingskostnader samt lägre risk. Som en konsekvens av will-fitters intåg i marknaden reduceras försäljningen för OEM-företagen. Will-fitters utgör därmed ett konkret hot inom eftermarknaden för en OEM såsom en biltillverkare. Eftermarknaden är en lukrativ marknad då vinstmarginalerna är höga relativt nybilsförsäljning. Då will-fitters är verksamma i marknaden tar de marknadsandelar och därmed tappar OEM en del av en lukrativ marknad. Denna studie undersöker konkurrenshinder relevanta för en OEM att implementera mot will-fitters och analyserar effekterna av att implementera dessa hinder. Resultaten baseras på en fallstudie utförd hos en biltillverkare, Volvo Cars. Studien fokuserar på biltillverkarens motorluftfilter, vilken är utsatt för konkurrens av will-fitters. Genom att kombinera teori gällande produktutveckling och konkurrenshinder med empiri från det studerade företaget togs sex relevanta konkurrens hinder fram för en OEM som konkurrerar med will-fitters. Dessa hinder är: patentering av en produkt, öka produktens komplexitet, höja de nödvändiga investeringarna, bidra med ökat värde, förbättra kundens uppfattning av produkten, sätta ett konkurrenskraftigt pris. Studien konkluderar konkurrenshindrens potential i att avskräcka konkurrens samt diskuterar hur implementation av hindren påverkar produktens underliggande kostnader. Slutligen påvisar studien att konkurrenshindren kan implementeras i syfte att avskräcka konkurrenter. Dock visar studien även att ingen av konkurrenshindren skapar en marknad utan några konkurrenter. Snarare, så är den påvisade effekten att antalet konkurrenter minskar. Visserligen är en reduktion av antalet konkurrenter i marknaden positivt för en OEM men en direkt korrelation med ökad marknadsandel har inte kunnat påvisas.

Clean air is a global health concern. Each year more than seven million people across the globe perish from breathing poor quality air. Development of high efficiency particulate air (HEPA) filters demonstrate an effort to mitigate dangerous aerosol hazards at the point of production. The nuclear power industry installs HEPA filters as a final line of containment of hazardous particles. Advancement air filtration technology is paramount to achieving global clean air. An exploration of analytical, experimental, computational, and machine learning models is presented in this dissertation to advance the science of air filtration technology. This dissertation studies, develops, and analyzes alternative air filtration materials and methods of analysis that optimize filtration efficiency and reduce resistance to air flow. Alternative nonwoven filter materials are considered for use in HEPA filtration. A detailed review of natural and synthetic fibers is presented to compare mechanical, thermal, and chemical properties of fibers to desirable characteristics for air filtration media. An experimental effort is undertaken to produce and evaluate new nanofibrous air filtration materials through electrospinning. Electrospun and stabilized nanofibrous media are visually analyzed through optical imaging and tested for filtration efficiency and air flow resistance. The single fiber efficiency (SFE) analytical model is applied to air filtration media for the prediction of filtration efficiency and air flow resistance. Digital twin replicas of nonwoven nanofibrous media are created using computer scripting and commercial digital geometry software. Digital twin filters are visually compared to melt-blown and electrospun filters. Scanning electron microscopy images are evaluated using a machine learning model. A convolutional neural network is presented as a method to analyze complex geometry. Digital replication of air filtration media enables coordination among experimental, analytical, machine learning, and computational air filtration models. The value of using synthetic data to train and evaluate computational and machine learning models is demonstrated through prediction of air filtration performance, and comparison to analytical results. This dissertation concludes with discussion on potential opportunities and future work needed in the continued effort to advance clean air technologies for the mitigation of a global health and safety challenge.

Technische Systeme nutzen sich ab. Dadurch bedingt kommt es zu Ausfällen. Um die Funktionstüchtigkeit von abgenutzten technischen Systemen wiederherzustellen, werden Instandsetzungsmaßnahmen durchgeführt. Da die Folgen eines unerwartet eintretenden Ausfalls drastisch sein können, ist es sinnvoll, das Abnutzungsverhalten eines technischen Systems vorherzusagen und so den Zeitpunkt von Instandsetzungsmaßnahmen zielgerichtet zu planen. Die Erstellung von Abnutzungsprognosen wird dadurch erschwert, dass sich technische Systeme oft variabel, in Abhängigkeit von auf sie einwirkenden Beanspruchungen, abnutzen. Außerdem wird diese Abnutzungsvariabilität von betriebsbedingten Einflüssen überlagert, was deren Modellierung erschwert. Im Rahmen dieser Arbeit wurden deshalb Lösungsansätze entwickelt, die es ermöglichen, die Abnutzungsvariabilität eines technischen Systems in Abnutzungsprognosen zu integrieren und dabei betriebsbedingte Einflüsse zu berücksichtigen. Somit können Instandsetzungsmaßnahmen präziser geplant, Ressourcen geschont sowie Kosten reduziert werden. / Technical systems are prone to deterioration. This leads to negative consequences like break-downs. Maintenance actions are executed in order to transfer technical systems back into healthy states. If break downs occur suddenly, the consequences can be dramatic. Therefore, it is reasonable to schedule maintenance actions based on health-state predictions. Thereby, health state predictions are impeded by the fact that technical systems often deteriorate variably, depending on certain stress factors. Furthermore, the effects of variable deterioration behavior can be hidden by system specific behavior. Thus, approaches are shown which integrate variable deterioration behavior into healthstate predictions while influences caused by the system specific behavior are considered. Consequently, maintenance actions can be scheduled more efficiently which spares resources and reduces costs.

The aim of this thesis is to description and comparison of solutions, demountable connection of the lid and box enclosure air filters for motor vehicles, developed and used by the manufacturing concern MANN + HUMMEL, for which air filtration only one part of a broad portfolio of filtration systems for the automotive industry in the world scale. Another part of this thesis will be one of the chosen optimization methods of connection and implementation of alternative proposals design solutions, including the selection of the best solution, creating design calculation, 3D design, FEA analysis and prototyping of an alternative connection method laser sintering. When creating the optimization and design of alternative design solutions can count on the possibility that existing solutions are taking all possible factors and that the best alternative design proposals show an improvement over existing at the expense of all other cells throughout the development of the product.

Technische Systeme nutzen sich ab. Dadurch bedingt kommt es zu Ausfällen. Um die Funktionstüchtigkeit von abgenutzten technischen Systemen wiederherzustellen, werden Instandsetzungsmaßnahmen durchgeführt. Da die Folgen eines unerwartet eintretenden Ausfalls drastisch sein können, ist es sinnvoll, das Abnutzungsverhalten eines technischen Systems vorherzusagen und so den Zeitpunkt von Instandsetzungsmaßnahmen zielgerichtet zu planen. Die Erstellung von Abnutzungsprognosen wird dadurch erschwert, dass sich technische Systeme oft variabel, in Abhängigkeit von auf sie einwirkenden Beanspruchungen, abnutzen. Außerdem wird diese Abnutzungsvariabilität von betriebsbedingten Einflüssen überlagert, was deren Modellierung erschwert. Im Rahmen dieser Arbeit wurden deshalb Lösungsansätze entwickelt, die es ermöglichen, die Abnutzungsvariabilität eines technischen Systems in Abnutzungsprognosen zu integrieren und dabei betriebsbedingte Einflüsse zu berücksichtigen. Somit können Instandsetzungsmaßnahmen präziser geplant, Ressourcen geschont sowie Kosten reduziert werden. / Technical systems are prone to deterioration. This leads to negative consequences like break-downs. Maintenance actions are executed in order to transfer technical systems back into healthy states. If break downs occur suddenly, the consequences can be dramatic. Therefore, it is reasonable to schedule maintenance actions based on health-state predictions. Thereby, health state predictions are impeded by the fact that technical systems often deteriorate variably, depending on certain stress factors. Furthermore, the effects of variable deterioration behavior can be hidden by system specific behavior. Thus, approaches are shown which integrate variable deterioration behavior into healthstate predictions while influences caused by the system specific behavior are considered. Consequently, maintenance actions can be scheduled more efficiently which spares resources and reduces costs.

Denna rapport presenterar en utvärdering av en centrifugal luftrenare från företaget Airission som användes i en infektionsavdelning på Karolinska Universitetssjukhuset. Airissions luftrenare rensar bort partiklar och aerosoler, genom så kallad centrifugalteknologi, en relativt oprövad teknologi för luftrening. Målet var att undersöka och försöka verifiera luftrenarens funktion och prestanda samt jämföra den med en konventionell luftrenare som använder traditionella tvåstegsfilter för att rena luft.För att utföra studien användes ett bioaerosolmätinstrument som i realtid mäter partikelnivåerna i rummet. Testerna utfördes under olika driftförhållanden och tidsintervall med luftrenare påslagen respektive avstängd. Datainsamlingen och analysen inkluderade beräkningen av medelvärdet, jämförelse av partikelnivåerna mellan de olika testfallen och beräkning av standardavvikelsen.Resultaten visade att Airissions centrifugala luftrenare fungerar väl för rening av luft från partiklar och aerosoler. Reningseffektiviteten var jämförbar med en konventionell luftrenare. Den var mer effektiv än en konventionell luftrenare utan användning av högeffektiva luftfilter, mer allmänt känt som HEPA-filter. En signifikant minskning av antalet partiklar i luften observerades medan luftrenaren var i drift. Det uppstod dock en del komplikationer vid appliceringen av HEPA-filtret, vilka kunde ha haft en negativ påverkan på båda luftrenarna. Sammanfattningsvis visar analysen att den tillämpade centrifugalteknologin hos Airissions luftrenare fungerar väl. Jämförelsen av den konventionella luftrenaren visar vissa fördelar med en luftrenare som använder centrifugal teknologi - både gällande effektivitet och kvalitet.Denna rapport bidrar till kunskapen om luftreningslösningar för att förbättra luftkvaliteten och minska spridningen av luftburna sjukdomar, framför allt i sjukhusmiljöer. Resultaten kan vara till nytta för fortsatt forskning och utveckling av mer effektiva luftrenare som i sin tur ger ett bättre skydd för patienter och sjukhuspersonal som exponeras för luftburna smittämnen. / This report presents an evaluation of a centrifugal air purifier from the company Airission used in an infectious ward at Karolinska University Hospital. Airission's air purifier removes particles and aerosols using centrifugal technology, a relatively untested technology for air purification. The goal was to investigate and attempt to verify the functionality and performance of the air purifier and compare it to a conventional air purifier that uses traditional two-stage filters for air purification.To conduct the study, a bioaerosol measuring instrument was used to measure real-time particle levels in the room. The tests were performed under different operating conditions and time intervals with the air purifier turned on and off. Data collection and analysis included calculating the mean values, comparing the particle levels between different test cases, and calculating the standard deviation.The results showed that Airission's centrifugal air purifier effectively purifies air from particles and aerosols. The purification efficiency was comparable to a conventional air purifier. It was more effective than a conventional air purifier without the use of highefficiency air filters, commonly known as HEPA filters. A significant reduction in the number of particles in the air was observed while the air purifier was in operation. However, some complications arose during the application of the HEPA filter, which could have had a negative impact on both air purifiers.In summary, the analysis demonstrates that the applied centrifugal technology in Airission's air purifier works well. The comparison with the conventional air purifier shows certain advantages of an air purifier that uses centrifugal technology - in terms of both efficiency and quality.This report contributes to the knowledge of air purification solutions to improve air quality and reduce the spread of airborne diseases, especially in hospital environments. The results can be useful for further research and development of more effective air purifiers, which in turn provide better protection for patients and hospital staff exposed to airborne pathogens.