Emissions and In-Cylinder Combustion Characteristics of Fischer-Tropsch and Conventional Diesel Fuels in a Modern CI Engine

Abstract

Increasingly stringent emissions regulations, rising oil prices, and an increased focus on environmental awareness are driving the search for clean, alternative fuels. Derived from natural gas, coal, and even biomass Fischer-Tropsch (FT) fuels are one such alternative. The inherently clean nature of FT diesel coupled with the fact that FT diesel exhibits similar physical properties to those of conventional diesel make FT diesel an ideal candidate as both a blending agent with and eventual replacement for conventional petroleum-based diesel fuels.The potential for emissions reduction with FT diesel fuels in laboratory engine tests and on-road vehicle tests is well documented. While a number of chemical and physical characteristics of FT fuels have been attributed to the observed reduction in emissions, the actual effects of both the fuel properties and in-cylinder combustion characteristics in modern diesel engines are still not well understood. In this study a 2002, six-cylinder, 5.9 liter, Cummins ISB 300 diesel engine, outfitted with an in-cylinder pressure transducer, was subjected to a subset of the Euro III 13-mode test cycle under steadystate operating conditions. Emissions and in-cylinder pressure measurements were conducted for neat FT diesel, low sulfur diesel (LSD), ultra-low sulfur diesel (ULSD), and a blend of FT/LSD. The experimental results show a significant reduction in regulated emissions with the neat FT fuel and a more than proportional reduction in particulate emissions for the blend. In order to provide further insight into the emissions behavior of the fuels, combustion characteristics were determined from a heat release analysis based on the in-cylinder pressure measurements. In addition, a detailed chemical analysis of the fuels and particulate emissions was carried out. The differences in the measured combustion characteristics and fuel properties were compared to the emissions variations between the fuels studied, and an explanation for the observed emissions behavior of the fuels was developed.

Load-Dependent Emission Factors and Chemical Characteristics of IVOCs from a Medium-Duty Diesel Engine

“…This trend is consistent with differences in combustion efficiency at different engine loads. Because the engine is optimized for high-load conditions and is least efficient at engine idle, IVOC emissions (at least those that are directly related to fuel combustion) are expected to decrease with increasing load. We have observed a similar relationship between IVOC emissions and engine load in our previous study of aircraft exhaust; similar load-dependent trends in POA and THC emissions have also been observed from heavy-duty direct-injection diesel engines …”

“…Exhaust emissions were sampled from an unheated dilution tunnel built and designed specifically for emissions characterization . A schematic of the experimental setup is provided in Figure S1.…”

“…Exhaust emissions were sampled from an unheated dilution tunnel built and designed specifically for emissions characterization. 27 A schematic of the experimental setup is provided in Figure S1. Briefly, engine exhaust is subsampled into the dilution tunnel from which IVOC emissions are sampled and characterized.…”

Investigation on the spray development, the combustion characteristics and the emissions of Fischer–Tropsch fuel and diesel fuel from direct coal liquefaction

“…Similar results have also been obtained by several groups of researchers. 5–10 In comparison with F–T diesel, DDCL has a lower cetane number and thus prolonged ignition delay, according to Zhuang et al 11–13 However, with increasing CO and HC emissions, low PM emissions can be achieved similar to those from F–T fuel. In spite of these contributions, the fuel properties can vary from manufacturer to manufacturer, and more experiments are necesssary in order to obtain more information about F–T diesel and DDCL.…”