Essence (hydrocarbure) | EPFL Graph Search

L'essence est un liquide inflammable, issu de la distillation du pétrole, utilisé comme carburant dans les moteurs à combustion interne. C'est un carburant pour moteur à allumage commandé (moteur essence). C'est un mélange d’hydrocarbures, auxquels peuvent être ajoutés des additifs pour carburants. De nombreux types d'essence (dont essences spéciales) sont fabriqués et mis sur le marché. On y trouve en moyenne :

20 à 30 % d’alcanes, hydrocarbures saturés de formule CnH2n+2 ;
5 % de cycloalcanes, hydrocarbures saturés cycliques ;
30 à 45 % d’alcènes, hydrocarbures insaturés ;
30 à 45 % d’hydrocarbures aromatiques, de la famille du benzène

L'énergie contenue dans l'essence est d'environ , ou (de pouvoir calorifique supérieur). C'est une forte densité d'énergie : environ plus d'énergie par kilogramme que le bois sec par exemple. Rôles particuliers des composants Parmi les alcanes, deux jouent un rôle particulier : l’octane et l’heptane . En effet, ces deux alca

This Intriguing Aircraft Concept Aims to Eliminate Airport Lines and Terminals

Claudio Leonardi

Conceived by Switzerland’s Ecole Polytechnique Fédérale de Lausanne, Clip-Air proposes a plane with a single flying wing encompassing the airframe, cockpit, and three engines, attached to a maximum of three interchangeable capsules a more flexible and efficient method of fleet management and a faster loading rate, Clip-Air would drastically cut travelling time and costs and reduce the likelihood of vacant flights. The system would also be more eco-friendly than existing technology, with a trio of pods flying beneath one wing set to generate fewer emissions and consume less fuel than three individual planes with the same capacity flying at equal altitude and speed. EPFL is also exploring the idea of using cleaner fuel types such as liquid hydrogen and biofuels in lieu of traditional gasoline.

2016

A high-resolution historical record of nutrients, trace elements and organochlorines (DDT and PCB) deposition in a drinking water reservoir (Lake Brêt, Switzerland) points at local and regional pollutant sources

Luiz Felippe De Alencastro, Dominique Grandjean

The 137Cs and 210Pb dating of a 61-cm long sediment core retrieved from a drinking water reservoir (Lake Bret) located in Switzerland revealed a linear and relatively high sedimentation rate (∼1 cm/year) over the last decades. The continuous centimeter scale measurements of physical (porewater and granulometry), organic (Corg, P, N, HI and OI index) and mineral (Cmin and lithogenic trace elements) parameters therefore enables reconstructing the environmental history of the lake and anthropogenic pollutant input (trace metals, DDT and PCBs) at high resolution. A major change in the physical properties of the lowermost sediments occured following the artificial rise of the dam in 1922. After ca. 1940, there was a long-term up-core increase in organic matter deposition attributed to enhance primary production and anoxic bottom water conditions, due to excessive nutrient input from a watershed predominantly used for agriculture that also received domestic effluents from two wastewater-treatment plants. This pattern contrasts with the terrigenius element input (Eu, Sc, Mg, Ti, Al, and Fe) which doubled after the rising of the dam but continuously decreased during the last 60 years. By comparison, the trace metals (Cu, Pb and Hg) present a slight enrichment factor (EF) only during the second part of the 20th century. Although maximum EF Pb (>2) occurred synchronously with the use of leaded gasoline in Switzerland (between ca. 1947 and 1985) the Hg and Cu profiles exhibited a relatively similar trend than Pb during the 20th century, therefore excluding the alkyl-lead added to petrol as the dominant (atmospheric) source of lead input to Lake Brêt. Conversely, the Cu profile that did not follow the decrease registered in Pb and Hg, suggesting an additional source of Cu probably linked to the impact of agricultural activities in the area. In absence of heavy industries in the catchment, the atmospheric deposition of DDT and PCBs via surface runoff follows the historical emissions of POPs in Switzerland. Such result highlights the regional contamination of freshwater resources by the large-scale emission of toxic industrial chemicals in the 1960s and 1970s as well as the efficiency of the regulatory measures subsequently taken.

Pergamon-Elsevier Science Ltd2013

Gasoline hybrid pneumatic engine for efficient vehicle powertrain hybridization

Zlatina Kirilova Dimitrova, François Maréchal

The largest applied convertors in passenger cars are the internal combustion engines – gasoline, diesel, adapted also for operating on alternative fuels and hybrid modes. The number of components that are necessary to realize modern future propulsion system is inexorably increasing. The need for efficiency improvement of the vehicle energy system induces the search for an innovative methodology during the design process. In this article the compressed air is investigated as an innovative solution for hybridization of small gasoline engine. The combination of a conventional IC engine and a pneumatic short-term storage system is an interesting approach to achieve lower fuel consumption. Instead of using a battery, a hybrid pneumatic vehicle uses a robust and inexpensive air pressure tank for energy storage. The fuel consumption benefit of the hybrid air system is assessed and the vehicle usages leading to the maximal fuel consumption benefits of the hybrid pneumatic powertrain are investigated. The hybrid pneumatic concept is applied on a largely deployed C Segment commercial vehicle with 3 cylinder gasoline engine. The lowest fuel consumption results are investigated on the usage of this vehicle.

Elsevier2015

Luiz Felippe De Alencastro, Dominique Grandjean

Pergamon-Elsevier Science Ltd2013