Fischer-Tropsch Fuels Impact on a Diesel Engine Performance
Paper in proceedings, 2000
It has been reported that Fischer Tropsch (F-T) diesel fuel is a high quality fuel, and therefore it has received attention as a low emission alternative fuel. Having low aromatic compounds, high cetane rating and almost zero sulfur content, the F-T diesel fuel shows advantages over conventional diesel fuel. However, in order to generalize such deductions and to fill the confirmation gaps, further investigation and combustion analysis have to be conducted.
The aim of this investigation was to reveal and analyze the effects of the Fischer-Tropsch (F-T) fuels on a research diesel engine performance. Since the engine performance is closely related to in-cylinder processes, a detailed thermodynamic analysis is performed by Burst to File high frequency sampling code and by the Dragon software, revealing the real thermochemistry history. This program has been tested on thousands of measured points and is today regularly used while analyzing test results from the single cylinder diesel engine. Experimental results have shown that F-T fuels have a remarkable impact not only on the emissions levels, but also on other energetic parameters of the engine. Heat release analysis (evaluated according to the “Dragon” software program and acquisition from “Burst to File” PC based sampling system) have shown that ignition delay, cylinder peak pressure, heat release gradient and indicated efficiency are affected as well.
As F-T fuels have some other combustion characteristics than conventional diesel fuels, the most expected effect would be observed on emission levels, particularly on NOx and soot formation. However, it was observed that other emissions such as HC and CO were remarkably affected as well. Also, a combination of the different F-T fuels mixture would lead to a better engine performance and lower emission levels. Therefore, different mixtures of the F-T fuels characterized by C chain-length variation were tested and their results were compared with those obtained from conventional fuel (MK1). The selected optimized F-T fuels mixture was further tested at 13 mode ECE test cycle and is considered as a good competitive alternative diesel fuel.