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. International Journal of Engine Research. 14(4):373-390. https://doi.org/10.1177/1468087412456688S373390144(2009). World Energy Outlook 2009. World Energy Outlook. doi:10.1787/weo-2009-enMonyem, A., & H. Van Gerpen, J. (2001). The effect of biodiesel oxidation on engine performance and emissions. Biomass and Bioenergy, 20(4), 317-325. doi:10.1016/s0961-9534(00)00095-7LAPUERTA, M., ARMAS, O., & RODRIGUEZFERNANDEZ, J. (2008). Effect of biodiesel fuels on diesel engine emissions. Progress in Energy and Combustion Science, 34(2), 198-223. doi:10.1016/j.pecs.2007.07.001Fisher, B. T., Knothe, G., & Mueller, C. J. (2010). Liquid-Phase Penetration under Unsteady In-Cylinder Conditions: Soy- and Cuphea-Derived Biodiesel Fuels Versus Conventional Diesel. Energy & Fuels, 24(9), 5163-5180. doi:10.1021/ef100594pFang, T., Lin, Y.-C., Foong, T. M., & Lee, C. (2009). Biodiesel combustion in an optical HSDI diesel engine under low load premixed combustion conditions. Fuel, 88(11), 2154-2162. doi:10.1016/j.fuel.2009.02.033Pastor, J. V., García-Oliver, J. M., Nerva, J.-G., & Giménez, B. (2011). Fuel effect on the liquid-phase penetration of an evaporating spray under transient diesel-like conditions. Fuel, 90(11), 3369-3381. doi:10.1016/j.fuel.2011.05.006Fisher, B. T., & Mueller, C. J. (2010). Liquid penetration length of heptamethylnonane and trimethylpentane under unsteady in-cylinder conditions. Fuel, 89(10), 2673-2696. doi:10.1016/j.fuel.2010.04.024Kim, H. J., Park, S. H., Suh, H. K., & Lee, C. S. (2009). Atomization and Evaporation Characteristics of Biodiesel and Dimethyl Ether Compared to Diesel Fuel in a High-Pressure Injection System. Energy & Fuels, 23(3), 1734-1742. doi:10.1021/ef800811gSuh, H. K., Roh, H. G., & Lee, C. S. (2008). Spray and Combustion Characteristics of Biodiesel∕Diesel Blended Fuel in a Direct Injection Common-Rail Diesel Engine. Journal of Engineering for Gas Turbines and Power, 130(3). doi:10.1115/1.2835354Pickett, L. M., & Siebers, D. L. (2006). Soot Formation in Diesel Fuel Jets Near the Lift-Off Length. International Journal of Engine Research, 7(2), 103-130. doi:10.1243/146808705x57793Pickett, L. M., Kook, S., Persson, H., & Andersson, Ö. (2009). Diesel fuel jet lift-off stabilization in the presence of laser-induced plasma ignition. Proceedings of the Combustion Institute, 32(2), 2793-2800. doi:10.1016/j.proci.2008.06.082Yoo, C. S., Richardson, E. S., Sankaran, R., & Chen, J. H. (2011). A DNS study on the stabilization mechanism of a turbulent lifted ethylene jet flame in highly-heated coflow. Proceedings of the Combustion Institute, 33(1), 1619-1627. doi:10.1016/j.proci.2010.06.147Pastor, J. V., Payri, R., Gimeno, J., & Nerva, J. G. (2009). Experimental Study on RME Blends: Liquid-Phase Fuel Penetration, Chemiluminescence, and Soot Luminosity in Diesel-Like Conditions. Energy & Fuels, 23(12), 5899-5915. doi:10.1021/ef9007328Benajes, J., Molina, S., Novella, R., & Amorim, R. (2010). Study on Low Temperature Combustion for Light-Duty Diesel Engines. Energy & Fuels, 24(1), 355-364. doi:10.1021/ef900832cPickett, L. M., & Siebers, D. L. (2002). An investigation of diesel soot formation processes using micro-orifices. Proceedings of the Combustion Institute, 29(1), 655-662. doi:10.1016/s1540-7489(02)80084-0Siebers, D. L., & Pickett, L. M. (2004). Injection Pressure and Orifice Diameter Effects on Soot in DI Diesel Fuel Jets. Thermo- and Fluid Dynamic Processes in Diesel Engines 2, 109-132. doi:10.1007/978-3-662-10502-3_7Pickett, L. M., & Siebers, D. L. (2004). Soot in diesel fuel jets: effects of ambient temperature, ambient density, and injection pressure. Combustion and Flame, 138(1-2), 114-135. doi:10.1016/j.combustflame.2004.04.006Cheng, A. S., Upatnieks, A., & Mueller, C. J. (2006). Investigation of the impact of biodiesel fuelling on NOx emissions using an optical direct injection diesel engine. International Journal of Engine Research, 7(4), 297-318. doi:10.1243/14680874jer05005Cheng, A. S. (Ed), Upatnieks, A., & Mueller, C. J. (2007). Investigation of Fuel Effects on Dilute, Mixing-Controlled Combustion in an Optical Direct-Injection Diesel Engine. Energy & Fuels, 21(4), 1989-2002. doi:10.1021/ef0606456Klein-Douwel, R. J. H., Donkerbroek, A. J., van Vliet, A. P., Boot, M. D., Somers, L. M. T., Baert, R. S. G., … ter Meulen, J. J. (2009). Soot and chemiluminescence in diesel combustion of bio-derived, oxygenated and reference fuels. Proceedings of the Combustion Institute, 32(2), 2817-2825. doi:10.1016/j.proci.2008.06.140Fang, T., & Lee, C. F. (2009). Bio-diesel effects on combustion processes in an HSDI diesel engine using advanced injection strategies. Proceedings of the Combustion Institute, 32(2), 2785-2792. doi:10.1016/j.proci.2008.07.031Payri, F., Pastor, J. V., Nerva, J.-G., & Garcia-Oliver, J. M. (2011). Lift-Off Length and KL Extinction Measurements of Biodiesel and Fischer-Tropsch Fuels under Quasi-Steady Diesel Engine Conditions. SAE International Journal of Engines, 4(2), 2278-2297. doi:10.4271/2011-24-0037Kook, S., & Pickett, L. M. (2012). Liquid length and vapor penetration of conventional, Fischer–Tropsch, coal-derived, and surrogate fuel sprays at high-temperature and high-pressure ambient conditions. Fuel, 93, 539-548. doi:10.1016/j.fuel.2011.10.004Settles, G. S. (2001). Schlieren and Shadowgraph Techniques. doi:10.1007/978-3-642-56640-0Pickett, L. M., Manin, J., Genzale, C. L., Siebers, D. L., Musculus, M. P. B., & Idicheria, C. A. (2011). Relationship Between Diesel Fuel Spray Vapor Penetration/Dispersion and Local Fuel Mixture Fraction. SAE International Journal of Engines, 4(1), 764-799. doi:10.4271/2011-01-0686MUSCULUS, M., & PICKETT, L. (2005). Diagnostic considerations for optical laser-extinction measurements of soot in high-pressure transient combustion environments. Combustion and Flame, 141(4), 371-391. doi:10.1016/j.combustflame.2005.01.013Williams, T. C., Shaddix, C. R., Jensen, K. A., & Suo-Anttila, J. M. (2007). Measurement of the dimensionless extinction coefficient of soot within laminar diffusion flames. International Journal of Heat and Mass Transfer, 50(7-8), 1616-1630. doi:10.1016/j.ijheatmasstransfer.2006.08.024Kook, S., & Pickett, L. M. (2011). Soot volume fraction and morphology of conventional and surrogate jet fuel sprays at 1000-K and 6.7-MPa ambient conditions. Proceedings of the Combustion Institute, 33(2), 2911-2918. doi:10.1016/j.proci.2010.05.073De Francqueville, L., Bruneaux, G., & Thirouard, B. (2010). Soot Volume Fraction Measurements in a Gasoline Direct Injection Engine by Combined Laser Induced Incandescence and Laser Extinction Method. SAE International Journal of Engines, 3(1), 163-182. doi:10.4271/2010-01-0346Musculus, M. P. B., & Kattke, K. (2009). Entrainment Waves in Diesel Jets. SAE International Journal of Engines, 2(1), 1170-1193. doi:10.4271/2009-01-1355Desantes, J. M., Pastor, J. V., García-Oliver, J. M., & Pastor, J. M. (2009). A 1D model for the description of mixing-controlled reacting diesel sprays. Combustion and Flame, 156(1), 234-249. doi:10.1016/j.combustflame.2008.10.008Idicheria, C. A., & Pickett, L. M. (2011). Ignition, soot formation, and end-of-combustion transients in diesel combustion under high-EGR conditions. International Journal of Engine Research, 12(4), 376-392. doi:10.1177/1468087411399505Aizawa, T., & Kosaka, H. (2008). Investigation of early soot formation process in a diesel spray flame via excitation—emission matrix using a multi-wavelength laser source. International Journal of Engine Research, 9(1), 79-97. doi:10.1243/14680874jer01407Bruneaux, G. (2008). Combustion structure of free and wall-impinging diesel jets by simultaneous laser-induced fluorescence of formaldehyde, poly-aromatic hydrocarbons, and hydroxides. International Journal of Engine Research, 9(3), 249-265. doi:10.1243/14680874jer0010

A systems approach to risk and resilience analysis in the woody-biomass sector: A case study of the failure of the South African wood pellet industry

© 2017 Elsevier Ltd Currently more than 600 million of the 800 million people in SSA are without electricity, and it is estimated that an additional 2500 GW of power is required by 2030. Although the woody-biomass market in the developed world is relatively mature, only four woody-biomass plants in SSA have been established, all of which were closed by 2013. With its affordable labour, favourable climate and well-established forestry and agricultural sectors, South Africa appears to have the potential for a successful woody-biomass industry. This paper documents a first attempt at analysing why these plants failed. It aims to contextualise the potential role of a sustainable woody-biomass sector in South Africa, through firstly developing a SES-based analytical framework and secondly, using this to undertake a retrospective resilience-based risk assessment of the four former woody-biomass pellet plants in order to identify strategies for increasing the resilience of the industry. The SES-based framework advances previous theory, which usually focuses on natural resources and their supply, by introducing a production process (with inputs and outputs), internal business dynamics and ecological variable interactions. The risk assessment can be used at a broad level to highlight important aspects which should be considered during feasibility assessments for new plants. Further work is proposed to focus on splitting the social-ecological system at different scales for further analysis, and to investigate the long-term ecological impacts of woody-biomass utilisation

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.