Fundamental spray and combustion measurements of soy methyl-ester biodiesel

Although biodiesel has begun to penetrate the fuel market, its effect on injection processes, combustion and emission formation under diesel engine conditions remains somewhat unclear. Typical exhaust measurements from engines running biodiesel indicate that particulate matter, carbon monoxide and unburnt hydrocarbons are decreased, whereas nitrogen oxide emissions tend to be increased. However, these observations are the result of complex interactions between physical and chemical processes occurring in the combustion chamber, for which understanding is still needed. To characterize and decouple the physical and chemical influences of biodiesel on spray mixing, ignition, combustion and soot formation, a soy methyl-ester (SME) biodiesel is injected into a constant-volume combustion facility under diesel-like operating conditions. A range of optical diagnostics is performed, comparing biodiesel to a conventional #2 diesel at the same injection and ambient conditions. Schlieren high-speed imaging shows virtually the same vapour-phase penetration for the two fuels, while simultaneous Mie-scatter imaging shows that the maximum liquid-phase penetration of biodiesel is higher than diesel. Differences in the liquid-phase penetration are expected because of the different boiling-point temperatures of the two fuels. However, the different liquid-phase penetration does not affect overall mixing rate and downstream vapour-phase penetration because each fuel spray has similar momentum and spreading angle. For the biodiesel and diesel samples used in this study, the ignition delay and lift-off length are only slightly less for biodiesel compared to diesel, consistent with the fuel cetane number (51 for biodiesel, 46 for diesel). Because of the similarity in lift-off length, the differences in equivalence ratio distribution at the lift-off length are mainly affected by the oxygen content of the fuels. For biodiesel, the equivalence ratio is reduced, which, along with the fuel molecular structure and oxygen content, significantly affects soot formation downstream. Spatially resolved soot volume fraction measurements obtained by combining line-of-sight laser extinction measurements with planar laser-induced incandescence imaging show that the soot concentration can be reduced by an order of magnitude for biodiesel. These integrated measurements of spray mixing, combustion and quantitative soot concentration provide new validation data for the development of computational fluid dynamics spray, combustion and soot formation models suitable for the latest biofuels.This work was supported by the Spanish Ministry of Science and Innovation for Jean-Guillaume Nerva's visiting research, through the OPTICOMB project [TRA2007-67961-C03-01].Nerva, J.; Genzale, CL.; Kook, S.; García Oliver, JM.; Pickett, LM. (2013). Fundamental spray and combustion measurements of soy methyl-ester biodiesel. 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Resolving the policy paradox: the case of biofuel production in Ireland

Purpose The purpose of this paper is to determine the status of policy design and policy implementation in the biofuel sector in Ireland. The focus of the work addresses the overarching operational context of the biofuel sector in Ireland and the role of different actors in shaping and resolving inconsistencies in policy outlook and practice. Design/methodology/approach This study used a qualitative research approach involving a series of semi-structured interviews with members of the relevant sub-groups concerned. This study sought to address two questions – whether current or proposed policy is likely to affect consumption of indigenous biofuel feedstocks in the biofuel sector and what are the controlling factors in the demand for indigenous feedstocks for biofuel. Findings Outcomes suggest that while Irish government policy recognises the need to support the development of renewable energy, it also operates under a number of parallel and potentially inconsistent paradigms in relation to biofuels as a renewable energy commodity. It is contended that the outcome of this position is a lack of coherent and coordinated policy in the area of biofuel production, including second generation biofuel using indigenous feedstocks. Originality/value This paper provides a new cross sectoral perspective on the status of biofuel policy in Ireland with particular reference to second generation biofuel feedstocks. It focuses analysis on the nature of policy-operational inconsistencies and the need for a deeper ecological perspective in governance

Is our everyday comfort for sale? : Preferences for demand management on the electricity market

In a European perspective, the electricity markets have been experiencing major changes via deregulation, new technologies and changes in the production mix. Together with the daily and seasonal peak hours on the demand side, the changing markets put pressure on increased flexibility to handle and sustain balance in the grid systems. This paper focuses on the demand side and analyzes preferences related to demand management of Swedish households energy use. Preferences are analyzed within the framework of choice experiments and people are faced with hypothetical electricity contracts. The respondents reveal their preferences for attributes related to external control of heating, household electricity and information dissemination (integrity). The results show that people put a substantial value on not being controlled, illustrated by compensations up to thousands of SEK for accepting a contract characterized by external control of energy use in various dimensions. In addition, the results show that household composition, age, gender and income play a role for the perceived discomfort from the external control and information dissemination.