Suchergebnisse

Plug-in hybrid electric vehicles (PHEVs) show a high pollutant emission variability that strongly depends on the operating conditions of the internal combustion engine. Additionally, studies indicate that driving situations outside of the real driving emissions boundary conditions can lead to substantial pollutant emission increases. The objective of this study is to measure and analyze the particulate number (PN) and nitrogen oxides (NOx) emissions of a Euro 6 PHEV for a selected real-world driving test route in the Stuttgart metropolitan area. For this purpose, the vehicle is set out with multiple measurement devices to monitor vehicle internal and external parameters. Particle distribution results show an overall uniform pattern, which allows a comparative analysis of the different test scenarios on the basis of the PN concentration. While the trip-average PN emissions are in good agreement, transient effects during highway driving can substantially increase emissions, whereas the fuel consumption does not necessarily increase in such situations. PN measurements including ultrafine particles (UFP) show a significant increase in urban emissions due to higher cold start emission peaks. Additionally, low ambient temperatures raise the uncertainty of NOx and PN cold start emissions. With regard to future emission regulations, which claim that vehicles need to be as clean as possible in all driving situations, PHEV emission investigations for further situations outside of the current legislations are required.

AbstractOverall, the detonation of munitions represents an environmentally clean reaction. Six kilotons of energetic materials were expended in this case study during training in 1996. These included nitrocellulose (55 percent), trinitrotoluene (TNT) (30 percent), nitroglycerine (5 percent), nitroguanidine (4 percent), dinitrotoluene (DNT) (3 percent), and Royal Dutch Explosive (RDX) (3 percent). Based on previously reported test data (BangBox), energetic detonation emissions of environmental concern were calculated to be less than 1 percent. This residue contains nitrogen oxides (88 percent), a mix of volatile organic compounds (11 percent), and possibly undetonated RDX (<1 percent). Preliminary assessment of emissions produced by munitions in this study indicates that both nitrogen oxide (NOX) and volatile organic compound (VOC) emissions are low relative to other NOX and VOC producing activities including emissions from biogenic (natural) sources. Though the amount of undetonated RDX is low, further work is needed to validate this number and determine whether this source represents any significant health or environmental impact.

AbstractAmmonia has been considered as a novel fuel for decarbonization purposes. However, emissions from combustion systems are still posing a problem. Therefore, experimental and numerical simulations have been conducted to study the concentration of exhaust emissions (Nitric oxide "NO", Nitrous oxide "N2O") from burning the ammonia/hydrogen (NH3/H2) blend 85/15 (vol%). The effects were measured at various thermal powers ranging 10 to 20 kW and with different Reynolds numbers from 20,000—40,000. The experimental points were numerically investigated in the Ansys CHEMKIN-Pro environment employing seven chemical kinetic mechanisms taken from the literature. All experiments have been undertaken at standard atmospheric conditions. The experimental results showed that both NO and N2O gradually increased when the Reynolds number increased from 20,000 to 40,000. Along with that, the concentration of NO emissions at the exhaust reported minimum level when the Re = 20,000 due to lower reactivity radical formation, all that led to a deterioration of the flame characteristics. Also, the integrated radical intensities of NO*, OH*, NH*, and NH2* demonstrate an increasing trend as Re increased from 20,000 to 40,000. In terms of thermal power, N2O suffered an abrupt decrease when the thermal power increased up to 15 kW, while the opposite occurs for NO. In addition, the radicals intensity of OH*, NH*and NH2* figures show an increase in their concentration when the thermal power increased up to 15 kW then decreased with increasing thermal intensity to reach 20 kW, reflecting into increased NO productions and decreased N2O levels. The numerical analysis showed that Stagni, Bertolino, and Bowen Mei were the most accurate mechanisms as these give a good prediction for NO and N2O. The study also showed that the chemical reaction (HNO + O2 ↔ NO + HO2) is the main source of NO formation. While the chemical reaction (NH + NO ↔ N2O + H) is responsible for the formation of N2O by consuming NO and when there will be abundance in NH radicals. Finally, dealing with a blended fuel of high ammonia concentration encourages ammonia chemistry to become more dominant in the flame. It decreases the flame temperature, hence lowering heat loss between the flame and the surrounding.

Abstract
The health risks associated with individual air pollutant exposures have been studied and documented, but in real-life, the population is exposed to a multitude of different substances, designated as mixtures. A body of literature on air pollutants indicated that the next step in air pollution research is investigating pollutant mixtures and their potential impacts on health, as a risk assessment of individual air pollutants may actually underestimate the overall risks. This review aims to synthesize the health effects related to air pollutant mixtures containing selected pollutants such as: volatile organic compounds, particulate matter, sulfur and nitrogen oxides. For this review, the PubMed database was used to search for articles published within the last decade, and we included studies assessing the associations between air pollutant mixtures and health effects. The literature search was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A number of 110 studies were included in the review from which data on pollutant mixtures, health effects, methods used, and primary results were extracted. Our review emphasized that there are a relatively small number of studies addressing the health effects of air pollutants as mixtures and there is a gap in knowledge regarding the health effects associated with these mixtures. Studying the health effects of air pollutant mixtures is challenging due to the complexity of components that mixtures may contain, and the possible interactions these different components may have.

The International Maritime Organization recently revised the regulations concerning nitrogen and sulphur oxides emissions from commercial ships. In this context, it is important to investigate how emission abatement technologies capable of meeting the updated regulation on nitrogen oxides emissions affect the performance of waste heat recovery units to be installed on board new vessels. The objective of this paper is to assess the potential fuel savings of installing an organic Rankine cycle unit on board a hypothetical liquefied natural gas-fuelled feeder ship operating inside emission control areas. The vessel complies with the updated legislation on sulphur oxides emissions by using a dual fuel engine. Compliance with the nitrogen oxides emission regulation is reached by employing either a high or low-pressure selective catalytic reactor, or an exhaust gas recirculation unit. A multi-objective optimization was carried out where the objective functions were the organic Rankine cycle unit annual electricity production, the volume of the heat exchangers, and the net present value of the investment. The results indicate that the prospects for attaining a cost-effective installation of an organic Rankine unit are larger if the vessel is equipped with a low-pressure selective catalytic reactor or an exhaust gas recirculation unit. Moreover, the results suggest that the cost-effectiveness of the organic Rankine cycle units is highly affected by fuel price and the waste heat recovery boiler design constraints.