Comparative study of three ways of using Jatropha curcas vegetable oil in a direct injection diesel engine

International audienc

Characterization, at Partial Loads, of the Combustion and Emissions of a Dual-Fuel Engine Burning Diesel and a Lean Gas Surrogate

For decentralized power generation in West Africa, gas from a small biomass gasification unit can be used as the main fuel in a dual-fuel engine with diesel as the pilot fuel. To study the combustion in this type of engine (Lister Petter), experiments were conducted with a surrogate gas composed of liquefied petroleum gas and nitrogen (LPGN2), the energy context of which is similar to that of syngas. The tests were conducted at different loads and for different diesel substitution rates. The combustion analysis showed that the LPGN2 mixture had an overall behaviour similar to neat diesel, while the pressure peaks were lower in dual-fuel mode. The results also indicated a longer ignition delay and a pronounced diffusive combustion phase leading to a lower indicated mean effective pressure with gas. The fuel efficiencies remained low in both mono- and dual-fuel operation. The relative instability of the combustion in dual-fuel mode gave rise to an increase in the coefficient of variation (COVIMEP). Compared to neat diesel, the engine running at low loads in dual-fuel mode showed higher emission levels of CO, a slight reduction of 2.5% of CO2 and a sub-stantial decrease of 73% for nitrogen oxides

Performance evaluation of satellite-based rainfall estimation across climatic zones in Burkina Faso

Satellite-based rainfall estimates are a good and cost-effective alternative to low-density rain gauges because they provide information for these areas. In this study, the accuracy of seven satellite-based precipitation datasets SPDs (TRMM-3B42v7, CHIRPSv2, RFEv2, ARC2, PERSIANN-CDR, GPCPv3.1, and TAMSATv3.1) was evaluated against ground-based observations. The performance of these datasets was evaluated at daily, dekadal, and monthly time scales from 2001 to 2014 using continuous and categorical statistical indicators. The results showed that CHIRPS and TAMSAT slightly underestimate precipitation in the Sahelian and Sudano–Sahelian zones by 2.1 to 8.3%, while the other datasets overestimate by between 3.7 and 13.2%. In the Sudanian zone, they all underestimated rainfall by 1.8 to 9.4%, except for GPCP and PERSIANN-CDR, which slightly overestimated rainfall in the range of 1.7 to 4.9%. The best performance was attributed to TAMSAT on the daily scale, while GPCP showed the weakest performance. CHIRPS dataset demonstrated the most accurate estimate of ground precipitation across all zones on the dekadal time scale, whereas TAMSAT showed unsatisfactory performance. On the monthly scale, CHIRPS again exhibits strong performance in the Sahelian and Sudano–Sahelian zones, ahead of TRMM-3B42. In the southernmost area, PERSIANN-CDR consistently exhibits good agreement with ground rainfall. In contrast to the results for the Sahelian and Sudano–Sahelian zones, larger errors were found for all SPDs within the Sudanian zone. The results suggest that the TAMSAT and CHIRPS datasets appear to be a good alternative source of information to rain gauge data. Therefore, these datasets could be valuable for different stakeholders such as meteorologists, hydrologists, and agronomists in Burkina Faso and support operational applications

Assessment of carbon dioxide emission factors from power generation in Burkina Faso

Power generation is the second largest source of greenhouse gases (GHGs), particularly carbon dioxide (CO2), in Burkina Faso's energy sector. When preparing the National Communications on Climate Change, Burkina Faso uses the default emission factors of the Intergovernmental Panel on Climate Change (IPCC) to estimate emissions from power generation. This study presents an assessment of CO2 emission factors from power generation for 2018 in Burkina Faso and an assessment of the contribution of renewable energy to the reduction of CO2 emissions. The national electricity company of Burkina Faso was chosen as the scope for this study. The estimation of emission factors for combustion is based on an analysis of fuels which are characterised in terms of molecular composition, density and water content. For CO2, the emission factor is 76 903 kg/TJ for the combustion of Heavy Fuel Oil (HFO) and 73 525 kg/TJ for that of Distillate Diesel Oil (DDO). Using these emission factors, the CO2 emissions attributable to power generation in 2018 were estimated at almost 580 Gg. The CO2 emission factor for thermal power generation was estimated at 0.663 kg/kWh and that of the electricity generation mix at 0.569 kg/kWh. Finally, the use of 14.25% renewable energy in electricity generation avoided 16.7% of CO2 emissions in 2018. The emission factor of electricity production decreases with the increase in the share of renewable energy in the energy mix

A New Experimental Method to Determine the Evaporation Coefficient of Trichloroethylene (TCE) in an Arid Soil

International audienceThis paper presents a new method to determine the evaporation coefficient of trichloroethylene using a new experimental device called " activity-meter ". This device and the associated method have been developed in the Laboratory of Mechanical Engineering of the University of Montpellier 2 (France). The influence of diffusion on the vapor pressure of trichloroethylene and the influence of temperature at the liquid-gas interface were first determined. The results show that diffusion phenomena have no influence on the vapor pressure of trichloroethylene beyond 400 seconds of experimental time and the temperature is almost constant during experiments. Thus, in order to take into account the effects that are only due to the variation of partial pressure of trichloroethylene at the liquid-gas interface, the time interval used is between 400 seconds and the time required to reach equilibrium. The influence of pressure and temperature on the evaporation coefficient of pure trichloroethylene in an arid soil was then highlighted. The results show that the evaporation coefficient of trichloroethylene decreases with total vapor pressure but increases with temperature. A comparative study on evaporation coefficients conducted on water, heptane and trichloroethylene shows that our results are in good agreement with results on volatility

Vers une génération plus « verte » de biodiesels

International audienceIn the world, oil provides 96% of transport needs, which mobilize 65% of the oil consumed and contribute 20% to CO2 emissions. One of the alternatives to reduce the consumption of fossil resources is the use of "biofuels". These biofuels are classified into three successive generations. The first generation biofuels come from the food parts of field crops: bioethanol and biodiesel. Second generation "advanced" biofuels come from lignocellulosic resources (wood, agricultural residues, etc.) valued either as bioethanol or synthetic hydrocarbons. A third generation is based on the culture of micro-algae producing fatty acids transformed into biodiesel. The first generation biodiesels, like those of the second and third generations, are subject to certain criticisms in particular the LUC (Land-Use Change) and the food versus energy competition. The objective of this work is to examine the interest of two promising ways. Biodiesel based on dedicated crops lead to reduced environmental impacts but play a role in the problem of LUC. While those based on residues are not part of the problem and show levels of reduction of greenhouse gas emissions between 83 and 90% against 60 to 80% for a conventional biodiesel compared to a fossil diesel fuel. Butyl esters of used edible oils and animal fats are displayed as "greener" biodiesels and represent an opportunity for second generation biofuels and for a greener oleochemistry.Dans le monde, le pétrole assure 96% des besoins des transports, lesquels mobilisent 65% dupétrole consommé et participent à hauteur de 20% aux émissions de CO2. Afin de réduire la consommationde ressources fossiles, une des alternatives est notamment l’utilisation de « biocarburants ». Cesbiocarburants sont classés en trois générations successives. Les biocarburants de première génération sontissus des parties alimentaires de plantes de grande culture : le bioéthanol et le biodiesel. Les biocarburantsdits « avancés » de seconde génération sont issus de ressources lignocellulosiques (bois, résidus agricoles...)valorisées soit en bioéthanol soit en hydrocarbures de synthèse. Une troisième génération repose sur la culture de micro-algues productrices d’acides gras transformés en biodiesel. Les biodiesels de première génération, tout comme ceux de deuxième et troisième générations, sont sujets à certaines critiques notamment le CAS (changement d’affectation des sols) et la compétition alimentaire/énergétique. L’objectif de ce travail est d’examiner l’intérêt de deux filières prometteuses. Les biodiesels basés sur des cultures dédiées conduisent à des impacts environnementaux plus réduits mais jouent un rôle dans la problématique des CAS. Alors que celles basées sur les résidus n’y entrent pas et montrent des niveaux de réduction des émissions de gaz à effet de serre entre 83 et 90% contre 60 à 80% pour un biodiesel classique par rapport à un carburant diesel fossile. Les esters butyliques d’huiles alimentaires usagées et de graisses animales s’affichent comme des biodiesels « plus verts » et représentent une opportunité pour les biocarburants de deuxième génération et pour une oléochimie « plus verte »

Study of Temperature Fields and Heavy Metal Content in the Ash and Flue Gas Produced by the Combustion of Briquettes Coming from Paper and Cardboard Waste

The present study focused on the combustion of four types of briquettes made from paper and cardboard waste produced in Ouagadougou (Burkina Faso). Rotary and tubular kilns were used to study the combustion. The combustion mean temperatures, nitrogen, phosphorus and potassium (NPK) content in the ash and heavy metals content in the ash and the flue gas were analyzed. The combustion steady phase mean temperatures ranged from 950 °C to 750 °C were obtained according to briquettes type. The temperature favored the transfer of the heavy metal in the flue gas comparatively to the ash mainly for Hg, Cd and Pb. The Pb, Hg and Mn content in flue gas and the ash are higher than their content in the parent wood used for paper production due to the additive during the manufacturing process. The results showed a high content of heavy metal in flue gas produced by combustion of briquette made with office paper and in the ash for the briquette made of corrugated cardboard. Furthermore, the low heavy metal contain in the ash allow their use for soil amendment. However, ash contained a low proportion of NPK (less than 2%) which does not allow their usage as fertilizer alone