Effect of Operating and Sampling Conditions on the Exhaust Gas Composition of Small-Scale Power Generators

Small stationary diesel engines, like in generator sets, have limited emission control measures and are therefore responsible for 44% of the particulate matter (PM) emissions in the United States. The diesel exhaust composition depends on operating conditions of the combustion engine. Furthermore, the measurements are influenced by the used sampling method. This study examines the effect of engine loading and exhaust gas dilution on the composition of small-scale power generators. These generators are used in different operating conditions than road-transport vehicles, resulting in different emission characteristics. Experimental data were obtained for gaseous volatile organic compounds (VOC) and PM mass concentration, elemental composition and nitrate content. The exhaust composition depends on load condition because of its effect on fuel consumption, engine wear and combustion temperature. Higher load conditions result in lower PM concentration and sharper edged particles with larger aerodynamic diameters. A positive correlation with load condition was found for K, Ca, Sr, Mn, Cu, Zn and Pb adsorbed on PM, elements that originate from lubricating oil or engine corrosion. The nitrate concentration decreases at higher load conditions, due to enhanced nitrate dissociation to gaseous NO at higher engine temperatures. Dilution on the other hand decreases PM and nitrate concentration and increases gaseous VOC and adsorbed metal content. In conclusion, these data show that operating and sampling conditions have a major effect on the exhaust gas composition of small-scale diesel generators. Therefore, care must be taken when designing new experiments or comparing literature results

The possible role of microfibril angle of Hemp fibre during fatigue tests and its determination using Wide-Angle X-ray diffraction

The orientation of the microfibril of cellulose in cell wall undeniably plays a predominant role in the elastic properties of natural fibres. In particular, the reorientation of the microfibrils is supposed to be involved in the stiffening phenomena of fibres under cyclic loading. In order to measure the MFA on natural fibres, this work proposed a method based on Wide Angle X-ray Scattering (WAXS). The ultimate goal of this work is to couple cyclic loading and MFA measurement in the near future

Sandwich panels with Arundo Donax core and flax fibre skins

Sandwich panels are structures employed in many different applications. Here, sandwich panels with the core made of Arundo donax rings and the skins made of flax fibre-reinforced epoxy composites are proposed. The influence of the surface roughness of the rings on the mechanical properties is investigated. Pull-off tests between the ring and the skin were carried out to understand how sandpaper polishing can affect the adhesion between the skin and the core. The sandwich panel is characterized by three points bending tests. The results show a significant influence of the polishing treatment on the ring lateral surfaces

Nonlinear tensile behaviour of elementary hemp fibres: a numerical investigation of the relationships between 3D geometry and tensile behaviour

International audienc

Towards the design of high-performance plant fibre composites

For the past 15 years, there has been tremendous interest and technological development concerning biocomposites. Plant fibres can be derived from a multitude of natural agro-sources, with the preferred choice as a composite reinforcement often being driven by abundance, geographical location, and historical use. While from a product designer's or engineer's point of view, all plant cell walls are 'similar', they have indeed substantial morphological and mechanical diversity linked to their structure, biochemical composition and the plant growing conditions. Here, we provide a holistic overview of the main types of plant cell walls used as polymer reinforcements. The relationship between their structures and properties, in constant link with potential associated composite, is specifically discussed. Then, the fibre extraction and cultivation modes are compared, through an environmental assessment. We also show how a scientist's point of view on cell wall structure and associated experimental approach lead to distinct results; following a critical review, we make recommendations on appropriate characterisation. A final discussion highlights the pertinent parameters that accurately define a composite reinforcement fibre. The review will serve as a handbook reference for researchers and designers in the field of biomaterials for appropriate selection of plant cell walls for specific composite applications

Model-based decision support for assessing the playability of heritage musical instruments

International audienc