Branched versus linear alkane adsorption in carbonaceous slit pores
- PDF / 881,440 Bytes
- 11 Pages / 595.276 x 790.866 pts Page_size
- 87 Downloads / 154 Views
Branched versus linear alkane adsorption in carbonaceous slit pores A. Harrison • R. F. Cracknell • J. Krueger-Venus L. Sarkisov
•
Received: 18 May 2013 / Accepted: 7 October 2013 / Published online: 20 October 2013 Ó Springer Science+Business Media New York 2013
Abstract The presence of carbonaceous deposits on the internal surfaces of a spark ignition engine has been linked in the literature to impaired vehicle performance, as manifested by increased knocking, higher fuel consumption, higher emissions and other adverse effects. One of the proposed mechanisms, in which the deposits affect the processes in the engine, is the adsorption and desorption of fuel components in the pores within the deposit. In this article we investigate this mechanism in more detail by considering single component adsorption of normal and branched alkanes in selected model slit pores representing the structure of the deposits. We further extend these studies to the binary mixture of normal heptane and isooctane, corresponding to a primary reference fuel blend. In particular, we show that in larger pores adsorption selectivity towards isooctane is about 1.2 on average throughout ˚ pore the pressure range. However, in the smaller 10 A selectivity towards isooctane can be in excess of three as a result of packing effects. These results are then placed in the context of engine performance issues.
Electronic supplementary material The online version of this article (doi:10.1007/s10450-013-9589-1) contains supplementary material, which is available to authorized users. A. Harrison L. Sarkisov (&) Institute for Materials and Processes, The University of Edinburgh, Edinburgh, UK e-mail: [email protected] R. F. Cracknell Shell Projects and Technology, Shell Technology Centre Thornton, Chester, UK J. Krueger-Venus Shell Projects and Technology, Shell Global Solutions (Deutschland) GmbH, Hamburg, Germany
Keywords Adsorption Simulation Slit pore Alkane Branched Engine deposit
1 Introduction This article continues a series of recent publications aimed at understanding adsorption phenomena in engine deposits (Pinto da Costa et al. 2009, 2011). These deposits are mainly carbonaceous materials which accumulate on the majority of the surfaces inside the internal gasoline combustion engine. The mechanism of their formation is not yet clearly understood. However, it is generally accepted that they derive primarily from the incomplete combustion of some of the fuel components and fuel additives (Kalghatgi 1990, 1995). Engine deposits are highly heterogeneous porous materials, both structurally and chemically, with carbon constituting only between 65 and 75 % of the material by weight depending on its location in the engine and other parameters (Pinto da Costa et al. 2011; Shu et al. 2012). Accumulation of these deposits has been linked with deterioration in engine performance, including slower response of the car when the accelerator is depressed, higher fuel consumption, and higher gaseous emissions (Kalghatgi 1990, 1995, 1996). In the
Data Loading...
