Real Driving NOx Emission Measurements of Vehicles with ICAD instruments for Plume Chasing

<p>Nitrogen Oxide (NO<sub>x</sub>) emissions from vehicles are a major cause of poor air quality in urban areas. The emissions per vehicle are regulated by the EURO Norm (EURO V: 2000mg/kWh, EURO VI: 460mg/kWh). Existing possibilities to measure whether the vehicles comply with the regulations (e.g. PEMS: Portable Emission Measurement System) are rare and costly. Within the framework of the EU project CARES (City Air Remote Emission Sensing) different remote emission sensing techniques and instruments are further developed. ‘Plume Chasing’ is one of them. With the Plume Chasing method, the emissions of a vehicle are measured in the wake of the investigated vehicle, i.e. in the diluted emission plume. This is done with a for this purpose optimized ICAD NO<sub>x</sub>-CO<sub>2</sub> instrument (Airyx GmbH), that allows fast (1s time resolution) and simple measurements with high accuracy (sub ppb for NO<sub>x</sub>) with a high measurement range (0-5000ppb). With these characteristics, it is perfectly suitable to detect malfunctioning or illegally manipulated emission control systems like SCR (selective catalytic reduction).</p><p>Several validation studies of Plume Chasing against the established PEMS have shown very good correlations. During a 3-day study in Sweden in November 2019, Plume Chasing measurements of a EURO V and a EURO VI truck were performed with activated as well as deactivated emission control system for several hours in different driving conditions. The derived Plume Chasing NO<sub>x</sub> emission values even for short measurement times of one and two minutes showed excellent correlation with the averaged PEMS NO<sub>x</sub> data of the trucks with R<sup>2</sup>~0.9. The study demonstrated the robustness of the Plume Chasing method in detecting high emitter trucks. To further test and optimise different measurement configurations and data analysis algorithms, within the CARES project several ICAD NO<sub>x</sub>-CO<sub>2 </sub>instruments are installed together with e.g. LICOR CO2-sensors or Condensation Particle Counters in a measurement vehicle from TNO, Netherlands.</p><p>Studies on German and Austrian highways in 2018 and 2019 showed that among several hundreds of trucks up to 35% of the EURO V trucks and up to 25% of the EURO VI trucks showed consistently high emissions exceeding the EURO norm limit, which provides strong evidence for a high number of defect or manipulated emission control systems. A recent study in Denmark showed 9,7% of the vehicles exceeding the standards. The vehicles were afterwards inspected by the police and defects or manipulations of the emission control system could be confirmed.</p>

Deactivation of a Vanadium-Based SCR Catalyst Used in a Biogas-Powered Euro VI Heavy-Duty Engine Installation

We have investigated how the exhaust gases from a heavy-duty Euro VI engine, powered with biogas impact a vanadium-based selective catalytic reduction (SCR) catalyst in terms of performance. A full Euro VI emission control system was used and the accumulation of catalyst poisons from the combustion was investigated for the up-stream particulate filter as well as the SCR catalyst. The NOx reduction performance in terms of standard, fast and NO2-rich SCR was evaluated before and after exposure to exhaust from a biogas-powered engine for 900 h. The SCR catalyst retains a significant part of its activity towards NOx reduction after exposure to biogas exhaust, likely due to capture of catalyst poisons on the up-stream components where the deactivation of the oxidation catalyst is especially profound. At lower temperatures some deactivation of the first part of the SCR catalyst was observed which could be explained by a considerably higher surface V4+/V5+ ratio for this sample compared to the other samples. The higher value indicates that the reoxidation of V4+ to V5+ is partially hindered, blocking the redox cycle for parts of the active sites.

Experimental adsorption and desorption characterization of a gasoline-fueled vehicle carbon canister for European application filled with n-butane and nitrogen mixtures

The evaporative emission control system (EVAP system) is the most commonly used strategy to limit the unburned petrol vapor emissions from a gasoline-fueled vehicle fuel tank, in order to comply with the international regulations on Volatile Organic Compounds (VOCs) emission. A carbon canister is used to collect and store the gasoline vapors generated in the tank, then it is purged by the engine intake manifold depression and the vapors are burned in the engine along with the fresh charge. In this activity, a 1.0 L carbon canister for European gasoline vehicles, provided by FCA, has been used for an experimental analysis, in order to characterize its adsorption and desorption behavior. A standard mixture of n-butane and nitrogen (40 g/h of n-butane, 50% vol. with nitrogen) has been used for loading the canister to breakthrough (2 g); canister purging has been performed with 3000 bed volumes of nitrogen flux at 25 L/min. Tests have been performed in FCA laboratories, at the Pomigliano Technical Center. Canister mass gain has been measured during the tests and after each test with a precision weight scale. Internal temperatures have also been measured by K-type thermocouples placed inside the carbon bed; due to the adsorption process, bed temperatures can reach 70 °C. After several tests, results on mass gain show an “aging” trend of the activated carbons.