• Energy Research

{"references": ["M. Salamanca, F. Mondragon, J. R. Agudelo, P. Benjumea, and A. Santamaria, \"Variations in the chemical composition and morphology of soot induced by the unsaturation degree of biodiesel and a biodiesel blend,\" Combust. Flame, vol. 159, no. 3, pp. 1100\u20131108, 2012.", "P. Benjumea, J. R. Agudelo, and A. F. Agudelo, \"Effect of the degree of unsaturation of biodiesel fuels on engine performance, combustion characteristics, and emissions,\" Energy and Fuels, vol. 25, no. 1, pp. 77\u201385, 2011.", "A. A. Refaat, \"Correlation between the chemical structure of biodiesel and its physical properties,\" Int. J. Environ. Sci. Technol., vol. 6, no. 4, pp. 677\u2013694, 2009.", "H. K. Imdadul, H. H. Masjuki, M. A. Kalam, N. W. M. Zulkifli, M. Kamruzzaman, M. M. Shahin, and M. M. Rashed, \"Evaluation of oxygenated n-butanol-biodiesel blends along with ethyl hexyl nitrate as cetane improver on diesel engine attributes,\" J. Clean. Prod., vol. 141, pp. 928\u2013939, 2017.", "N. Yilmaz and A. Atmanli, \"Experimental assessment of a diesel engine fueled with diesel-biodiesel-1-pentanol blends,\" Fuel, vol. 191, pp. 190\u2013197, 2017.", "C. Pagliaro, \"A deeper look at diesel fuel,\" The Chemistry of the Diesel Engine, 2012. (Online). Available: https://chembloggreen1.wordpress.com/page/2/. )Accessed: 07-Nov-2017).", "O. Bennett, \"Biofuels,\" House Commons Libr., pp. 1\u20139, 2011.", "European Parliament, \"Directive 2009/28/EC of the European Parliament and of the Council of 23 April 2009,\" Off. J. Eur. Union, vol. 140, no. 16, pp. 16\u201362, 2009.", "Volkswagen Group, \"Biodiesel statement,\" 2010.\n[10]\tS. Schober and M. Mittelbach, \"Iodine value and biodiesel: Is limitation still appropriate?,\" Lipid Technol., vol. 19, no. 12, pp. 281\u2013284, 2007.\n[11]\tG. Knothe, \"Analyzing biodiesel: standards and other methods,\" J. Am. Oil Chem. Soc., vol. 83, no. 10, pp. 823\u2013833, 2006.\n[12]\tD. Rutz and R. Janssen, \"Overview and Recommendations on Biofuel Standards for Transport in the EU (Contribution to WP 3.2 and WP 5.5),\" Munchen, Germany, 2006.\n[13]\tL. F. Ramirez-Verduzco, J. E. Rodriguez-Rodriguez, and A. del Rayo Jaramillo-Jacob, \"Predicting cetane number, kinematic viscosity, density and higher heating value of biodiesel from its fatty acid methyl ester composition,\" Fuel, vol. 91, no. 1, pp. 102\u2013111, 2012.\n[14]\tA. Sch\u00f6nborn, \"Influence of the molecular structure of biofuels on combustion in a compression ignition engine,\" University College London, 2009.\n[15]\tB. Ham, R. Shelton, B. Butler, and P. Thionville, \"Calculating the lodine value for marine oils from fatty acid profiles,\" J. Am. Oil \u2026, no. 20, pp. 1445\u20131446, 1998.\n[16]\tM. J. Murphy, J. D. Taylor, and R. L. Mccormick, \"Compendium of Experimental Cetane Number Data,\" Natl. Renew. Energy Lab., no. August, pp. 1\u201348, 2004."]} Hardly any neat biodiesel satisfies the European EN14214 standard for compression ignition engine application. To satisfy the EN14214 standard, various additives are doped into biodiesel; however, biodiesel additives might cause other problems such as increase in the particular emission and increased specific fuel consumption. In addition, the additives could be expensive. Considering the increasing level of greenhouse gas GHG emissions and fossil fuel depletion, it is forecasted that the use of biodiesel will be higher in the near future. Hence, the negative aspects of the biodiesel additives will likely to gain much more importance and need to be replaced with better solutions. This study aims to satisfy the European standard EN14214 by blending the biodiesels derived from sustainable feedstocks. Waste Cooking Oil (WCO) and Animal Fat Oil (AFO) are two sustainable feedstocks in the EU (including the UK) for producing biodiesels. In the first stage of the study, these oils were transesterified separately and neat biodiesels (W100 & A100) were produced. Secondly, the biodiesels were blended together in various ratios: 80% WCO biodiesel and 20% AFO biodiesel (W80A20), 60% WCO biodiesel and 40% AFO biodiesel (W60A40), 50% WCO biodiesel and 50% AFO biodiesel (W50A50), 30% WCO biodiesel and 70% AFO biodiesel (W30A70), 10% WCO biodiesel and 90% AFO biodiesel (W10A90). The prepared samples were analysed using Thermo Scientific Trace 1300 Gas Chromatograph and ISQ LT Mass Spectrometer (GC-MS). The GS-MS analysis gave Fatty Acid Methyl Ester (FAME) breakdowns of the fuel samples. It was found that total saturation degree of the samples was linearly increasing (from 15% for W100 to 54% for A100) as the percentage of the AFO biodiesel was increased. Furthermore, it was found that WCO biodiesel was mainly (82%) composed of polyunsaturated FAMEs. Cetane numbers, iodine numbers, calorific values, lower heating values and the densities (at 15 oC) of the samples were estimated by using the mass percentages data of the FAMEs. Besides, kinematic viscosities (at 40 °C and 20 °C), densities (at 15 °C), heating values and flash point temperatures of the biomixture samples were measured in the lab. It was found that estimated and measured characterisation results were comparable. The current study concluded that biomixture fuel samples W60A40 and W50A50 were perfectly satisfying the European EN 14214 norms without any need of additives. Investigation on engine performance, exhaust emission and combustion characteristics will be conducted to assess the full feasibility of the proposed biomixture fuels.

Reactivity-controlled compression ignition (RCCI) is a promising low-temperature combustion (LTC) strategy that results in low oxides of nitrogen (NOx) and soot emissions while maintaining high thermal efficiency. At the same time, RCCI leads to increased unburned hydrocarbon (HC) and carbon monoxide (CO) emissions in the exhaust, particularly under low loads. The current work experimented novel port-injected RCCI (PI-RCCI) strategy to overcome the high unburned emission limitations at low load conditions in RCCI. PI-RCCI is a port injection strategy in which low-reactivity fuel (LRF) is injected using a low-pressure injector, and the high-reactivity fuel (HRF) is injected through a high-pressure common rail direct injection (CRDI) injector. The low volatile HRF is injected into a heated fuel vaporizer maintained at 180°C in the intake manifold during the suction stroke. Modifying a single-cylinder, light-duty diesel engine with the necessary intake and fuel injection systems allows engine operation in both RCCI and PI-RCCI modes. Alternative fuels from waste resources such as waste cooking oil biodiesel (WCO) and plastic waste oil (WPO) are used as the HRF and LRF fuel in RCCI and PI-RCCI. To achieve maximum thermal efficiency in RCCI, the premixed energy ratio and the start of injection of the direct-injected fuel are optimized at all load conditions. The engine performance and exhaust emissions characteristics in PI-RCCI are compared with RCCI as a baseline reference. The results show a 70% and 48% reduction in CO and HC emissions, respectively, in PI-RCCI than in RCCI. Further, the brake thermal efficiency (BTE) was enhanced by around 20%, and the brake-specific fuel consumption (BSFC) was reduced by 13% in PI-RCCI. The NOx emissions decreased without any considerable changes in soot emission in PI-RCCI. The current study shows that fuels derived from waste resources can be used in RCCI and PI-RCCI modes with better engine performance and lower emissions.

Biodiesel is considered as one of the attractive alternatives to fossil diesel fuel. Although biodiesels reduces most of the harmful gas emissions, they normally releases higher NOx emissions compared to fossil diesel. The Selective Catalytic Reduction (SCR) is a well-known technique used in the OEM industry to mitigate NOx emission. However, this technique may not be suitable for application in low power density engines due to back pressure and clogging issues. On the other hand, Selective Non-Catalytic Reduction (SNCR) is used in relatively large combustion operations ie. boilers and incinerators. The main disadvantage of SNCR technique is the high temperature window for diesel engine exhaust temperature. This study introduces a new design concept, which is a combination of SCR and SNCR systems, for low power density diesel engines. The developed after-treatment system composed of two main parts, injection-expansion pipe and swirl chamber. The working principle is providing maximum mixing of the injected fluid and exhaust gas in the expansion chamber, then creating a maximum turbulence in the swirl chamber. In this regard, NOx emission can be reduced at relatively lower exhaust temperatures without using any catalyst. The CFD models of three design candidates were examined in terms of velocity magnitudes, turbulence intensity and particle residence time to select the optimum physical dimensions. The selected design was manufactured and installed to exhaust system of a 1.3 litre diesel engine. Two fluids distilled water and urea-water solution were injected separately at the same flow rate of 375 ml/min. Exhaust gas emissions of fossil diesel, sheep fat biodiesel – waste cooking oil biodiesel blend and chicken fat – cottonseed biodiesel blend were tested. No significant changes in CO2 and HC emissions were observed. However, it was found that distilled water injection reduced CO and NO emissions by about 10% and 6% for fossil diesel; and by about 9% and 7% for biodiesels operation respectively. The urea-water injection led to reductions in CO and NO emissions by about 60% and 13% for fossil diesel; and by about 45% and 15% for biodiesels respectively.

Liquids and gases produced through biomass pyrolysis have potential as renewable fuels to replace fossil fuels in conventional internal combustion engines. This review compares the properties of pyrolysis fuels, produced from a variety of feedstocks and using different pyrolysis techniques, against those of fossil fuels. High acidity, the presence of solid particles, high water content, high viscosity, storage and thermal instability, and low energy content are typical characteristics of pyrolysis liquids. A survey of combustion, performance and exhaust emission results from the use of pyrolysis liquids (both crude and up-graded) in compression ignition engines is presented. With only a few exceptions, most authors have reported difficulties associated with the adverse properties of pyrolysis liquids, including: corrosion and clogging of the injectors, long ignition delay and short combustion duration, difficulty in engine start-up, unstable operation, coking of the piston and cylinders and subsequent engine seizure. Pyrolysis gas can be used more readily, either in spark ignition or compression ignition engines; however, NO reduction techniques are desirable. Various approaches to improve the properties of pyrolysis liquids are discussed and a comparison of the properties of up-graded vs. crude pyrolysis liquid is included. Further developments in up-gradation techniques, such as hydrocracking and bio-refinery approaches, could lead to the production of green diesel and green gasoline. Modifications required to engines for use with pyrolysis liquids, for example in the fuel supply and injection systems, are discussed. Storage stability and economic issues are also reviewed. Our study presents recent progress and important R&D areas for successful future use of pyrolysis fuels in internal combustion engines.

Jatropha biodiesel was produced from neat jatropha oil using both esterification and transesterification processes. The free fatty acid value content of neat jatropha oil was reduced to approximately 2% from 12% through esterification. Aluminium oxide (Al2O3) and cerium oxide (CeO2) nanoparticles were added separately to jatropha biodiesel in doses of 100 ppm and 50 ppm. The heating value, acid number, density, flash point temperature and kinematic viscosity of the nanoadditive fuel samples were measured and compared with the corresponding properties of neat fossil diesel and neat jatropha biodiesel. Jatropha biodiesel with 100 ppm Al2O3 nanoparticle (J100A100) was selected for engine testing due to its higher heating value and successful amalgamation of the Al2O3 nanoparticles used. The brake thermal efficiency of J100A100 fuel was about 3% higher than for neat fossil diesel, and was quite similar to that of neat jatropha biodiesel. At full load, the brake specific energy consumption of J100A100 fuel was found to be 4% higher and 6% lower than the corresponding values obtained for neat jatropha biodiesel and neat fossil diesel fuels respectively. The NOx emission was found to be 4% lower with J100A100 fuel when compared to jatropha biodiesel. The unburnt hydrocarbon and smoke emissions were decreased significantly when J100A100 fuel was used instead of neat jatropha biodiesel or neat fossil diesel fuels. Combustion characteristics showed that in almost all loads, J100A100 fuel had a higher total heat release than the reference fuels. At full load, the J100A100 fuel produced similar peak in-cylinder pressures when compared to neat fossil diesel and neat jatropha biodiesel fuels. The study concluded that J100A100 fuel produced better combustion and emission characteristics than neat jatropha biodiesel.

A number of technological challenges need to be overcome if algae are to be utilized for commercial fuel production. Current economic assessment is largely based on laboratory scale up or commercial systems geared to the production of high value products, since no industrial scale plant exits that are dedicated to algal biofuel. For macroalgae (‘seaweeds’), the most promising processes are anaerobic digestion for biomethane production and fermentation for bioethanol, the latter with levels exceeding those from sugar cane. Currently, both processes could be enhanced by increasing the rate of degradation of the complex polysaccharide cell walls to generate fermentable sugars using specifically tailored hydrolytic enzymes. For microalgal biofuel production, open raceway ponds are more cost-effective than photobioreactors, with CO2 and harvesting/dewatering costs estimated to be ~50% and up to 15% of total costs, respectively. These costs need to be reduced by an order of magnitude if algal biodiesel is to compete with petroleum. Improved economics could be achieved by using a low-cost water supply supplemented with high glucose and nutrients from food grade industrial wastewater and using more efficient flocculation methods and CO2 from power plants. Solar radiation of not <3000 h·yr−1 favours production sites 30° north or south of the equator and should use marginal land with flat topography near oceans. Possible geographical sites are discussed. In terms of biomass conversion, advances in wet technologies such as hydrothermal liquefaction, anaerobic digestion, and transesterification for algal biodiesel are presented and how these can be integrated into a biorefinery are discussed.

Abstract Biodiesel produced from single feedstocks has many challenges due to variations in the oil properties. The flex-mix approach is a long-term solution for turning mixed feedstock into high-quality biodiesels. In this investigation, a pre-mixed used cooking oil and animal fat (pig fat) mixture (from 20% to 80%) was transesterified to produce flex-mix methyl ester (FMME). The FMME fuel characteristics were tested and compared to biodiesel standards. Generally, biodiesel emits higher oxides of nitrogen (NO x ) gas due to the presence of highly unsaturated compounds and oxygen. The present study aims to address this issue by adopting the flex-mix approach in combination with fuel injection strategies (400, 500 and 600 bar), exhaust gas recirculation (EGR 10%, 20% and 30%) and variable compression ratio (CR 17.5:1, 20:1 and 22:1). At a CR of 22 and an injection pressure (P inj) of 600 bar, the FMME fuel without EGR shows a minimum reduction in brake thermal efficiency of 0.15% when compared to diesel. Nitric oxide gas emissions decreased by nearly 50% for all P inj and EGR values, but they rose when the compression ratio was increased to 20 and 22. Smoke and hydrocarbon emissions also increased with the exhaust gas proportion. The engine performance with FMME fuel was found to be equivalent to that with fossil diesel fuel. According to the findings, the flex-mix approach could be a long-term alternative to producing renewable fuel for off-road diesel engine application.