G. Skevis

Assessment of Chemical Markers for Heat-Release Rate Correlations in Laminar Premixed Flames

There is considerable interest in formulating practical correlations for the quantification of heat-release rate in flames via appropriate chemical markers, mainly due to difficulties in obtaining a direct estimation of the former. Experimental and numerical studies performed in methane-air flames have identified corrections between suitable kinetic information and heat-release rate. The present work investigates the validity of corrections developed for methane to the combustion of other fuel classes (e.g., alcohols, unsaturated hydrocarbons, and aromatics), and proposes a methodological approach for the development of generic correlations. Numerical assessment of such correlations and their underlying methodology is performed on the basis of experimental data from 24 laminar premixed flames, utilizing a single, in-house, recently published C1–C6 detailed chemical kinetic model. It is shown that the proposed correlations are valid for methane-based fuels but they are largely inadequate for unsaturated fuels under rich conditions and for oxygenated fuels under most conditions. It is shown that heat-release rate is correlated with the dominant carbon path and that the oxidation chemistry of the parent alkyl radical is of pronounced importance. Alternatives to the proposed heat-release rate correlations are also proposed and assessed.

Experimental Investigation on the Influence of Simulated EGR Addition on Swirl-Stabilized CH4 Flames

AbstractLow-temperature combustion concepts for transport and power generation employ mixture dilution techniques, such as exhaust gas recirculation (EGR), that offer the potential of fuel flexibility, reduced pollutant emissions, and improved efficiency. These combustion modes, however, display a higher sensitivity to the compositional changes brought about by dilution, which in turn may have an adverse influence on the overall system performance. A fundamental study on the interactions between methane and simulated EGR was carried out on a swirl-stabilized, stoichiometric flame. The effects of varying levels and composition of diluents and preheating temperatures on flame structure and exhaust emissions, were experimentally investigated. Reductions of up to 90% and over 95% in NOx and CO emissions, respectively, where observed for higher levels of added diluents, whereas an increase in preheating temperature resulted in the opposite trends. It has been further demonstrated that, depending on fuel and th...

Potential for Implementation of Environmental Management Systems & the EU Ecolabel in the Marble Sector

Marble is a financially important and highly versatile material used extensively in construction, decoration and art. The marble industry however is generated with low production efficiency, high waste material generation, high production costs and overall lack of sustainable resources management. A step towards improving the energy efficiency and environmental performance of the marble sector would be the adoption of ecological schemes that are already into force both at national and international levels. The most commonly used schemes are Environmental Management Systems that are focused on the general environmental performance of the enterprise, such as the EU EMAS (Eco-Management and Audit Scheme) and the international EN ISO 14001:2004 standard and ecolabelling schemes, such as the EU Ecolabel, focusing on specific products or services. The present work aims to provide a concise summary of the technical requirements and procedures for obtaining such environmental certificates, assess the current state of the art in terms of environmental performance of a typical marble plant and enhance the ecological awareness of the sector. A detailed analysis of the technical requirements for achieving EMAS III registration and obtaining the EU Ecolabel for hard floor coverings is presented and the potential for a typical SME marble industry for meeting the above requirements is quantified. Possible measures that may improve the overall environmental impact are proposed. It is further shown that the process of meeting the necessary criteria for obtaining the above certificates will also lead to the adoption of best engineering practices and the production of high added value products.