If you’ve delved into diesel engines, you’ve likely pondered the question, “What exactly is a DPF?” A DPF Filters, or DPF, stands as an exhaust after-treatment device designed to capture particulate matter like soot and ash. Typically composed of a ceramic material fashioned into a honeycomb structure, the DPF plays a crucial role in mitigating emissions from diesel-powered vehicles. It traps and stores exhaust soot, necessitating periodic regeneration to burn off accumulated soot. This regeneration process is vital for preventing harmful exhaust emissions and the familiar black smoke often emitted by diesel vehicles during acceleration. In adhering to EPA 2007 emission standards, engine manufacturers widely employ DPFs to effectively trap particulate matter, contributing to the overall reduction of environmental impact.
The Air Quality Challenge:
Air pollution stands as a paramount environmental threat to health, posing risks such as stroke, heart disease, lung cancer, and various respiratory ailments, including asthma. The reduction of air pollution levels holds the key to alleviating the burden of these diseases. Disturbingly, in 2019, a staggering 99% of theglobal population resided in areas where the air quality fell below the guidelines set by the World Health Organization (WHO). The collective impact of both outdoor and household air pollution results in an alarming 6.7 million premature deaths each year. Specifically, outdoor air pollution, estimated to be responsible for 4.2 million premature deaths worldwide in 2019, disproportionately affects low- and middle-income countries, with 89% of these untimely deaths occurring in these regions. The WHO Southeast Asia and Western Pacific Regions bore the brunt of the highest number of premature deaths. To combat this crisis, promoting access to DPF filter cleaner emerges as a crucial step in significantly reducing ambient air pollution in specific regions.
Mechanism and Functionality:
The prevalent Diesel Particulate Filters (DPF) in current use predominantly feature cellular ceramic honeycomb structures. These filters employ channels that are sealed at alternating ends, a configuration designed to enhance filtration efficiency. The plugged ends, arranged in a checkerboard pattern, compel the exhaust, laden with soot particles, to traverse through the porous walls of the filter. While the exhaust gas is permitted to pass through these walls, the filter effectively captures soot particles, detaining them within the filter pores and forming a layer on top of the channel walls. This honeycomb design offers a substantial filtration area while minimising pressure losses, establishing itself as the standard wall-flow filter for a wide array of diesel exhaust filtration applications. Ceramic materials, renowned for their robust thermal durability, are extensively employed in the fabrication of these particulate filters. Among the commonly used ceramic materials for DPF filters are cordierite, silicon carbide, and aluminium titanate. These materials contribute to the overall effectiveness and longevity of DPF filters, ensuring their sustained performance in diverse diesel engine applications.
Emission Reduction Benefits of DPF Filters:
The enhanced compatibility feature of the DPF filter optimises continuous soot combustion, effectively maintaining low back pressure and reducing emissions by up to 99.96%. Tailoring the silicon carbide DPF material to specific applications involves considering various factors such as durability, compatibility, back pressure, service interval, and thermal regeneration strategy, ensuring optimal performance based on individual requirements. Within the retrofit market, providers of DPF systems face challenges imposed by legislative mandates to limit the increase of NO2 emissions from their systems. To address this, compliant catalyzed diesel particulate filters (cDPF) from various sources cater to both passive and active systems. For applications involving 500 kW engines and industrial settings, modular square elements enclosed in sleeving offer convenient integration into existing systems. Recommendations for coating the particulate filter are made based on the characteristics of the feedstock and gas, aiming to effectively control emissions.
Environmental Impact Assessment:
Diesel particulate filters are specifically designed to diminish the emission of diesel particulate matter, and their effectiveness in achieving this goal has been well-established. However, there is limited knowledge regarding their impact on other unregulated chemical components. In this study, source dilution sampling techniques were employed to assess the influence of a catalyzed diesel particulate filter on a broad range of chemical emissions from a heavy-duty diesel engine. The analysis encompassed various compounds, including both regulated criteria and unregulated substances such as particulate matter (PM), carbon monoxide (CO), hydrocarbons (HC), inorganic ions, trace metallic compounds, elemental and organic carbon (EC and OC), polycyclic aromatic hydrocarbons (PAHs), and other organic compounds. The findings indicated a significant reduction in the emissions of PM mass, CO, HC, metals, EC, OC, and PAHs.
Regulatory Landscape:
Initiated by Barry Sheerman, Member of Parliament for Huddersfield, the Westminster Commission for Road Air Quality (WCRAQ) comprises a coalition of scientists, air quality experts, fleet professionals, and urban planners. The primary objective of WCRAQ is to enhance the UK Government’s air quality policies and conduct research on air pollution from road transport with the ultimate goal of improving air quality in the UK. Diesel Particulate Filters (DPF) serve as highly efficient tools for capturing harmful particulates emitted from vehicle tailpipes. However, in the event of DPF damage, the filtration efficiency is compromised, leading to elevated levels of particulate matter emissions. Drawing from the experience in The Netherlands, it is estimated that approximately 10% of diesel cars exhibit issues such as damaged, tampered, or unlawfully removed DPF filters. This poses a significant threat to human health, particularly considering that most diesel cars on the road, registered from around 2010 onwards, should be equipped with DPFs. To address this concern, rigorous testing of diesel vehicles is crucial to mitigate fine and ultrafine particulate levels, consequently contributing to the improvement of road air quality. A recent report by DEFRA on the Emission of Air Pollutants in the UK emphasises the potential health risks associated with particulate matter, suggesting that these particles may enter the bloodstream and become lodged in vital organs, contributing to conditions such as asthma, COPD, and cardiovascular disease.
Also, read: What is the importance of DPF filter?