NO_x Emissions of Alternative Diesel Fuels:  A Comparative Analysis of Biodiesel and FT Diesel

Abstract

This study explores the diesel injection and combustion processes in an effort to better understand the differences in NO x emissions between biodiesel, Fischer−Tropsch (FT) diesel, and their blends with a conventional diesel fuel. Emissions studies were performed with each fuel at a variety of static fuel injection timing conditions in a single-cylinder DI diesel engine with a mechanically controlled, in-line, pump-line-nozzle fuel injection system. The dynamic start of injection (SOI) timing correlated well with bulk modulus measurements made on the fuel blends. The high bulk modulus of soy-derived biodiesel blends produced an advance in SOI timing compared to conventional diesel fuel of up to 1.1 crank angle degrees, and the lower bulk modulus of the FT diesel produced a delay in SOI timing of up to 2.4 crank angle degrees. Compared to conventional diesel fuel at high load, biodiesel fuel blends produced increases in NO x emissions of 6−9% while FT fuels caused NO x emissions to decrease 21−22%. Shifts in fuel injection timing, caused by bulk modulus differences, were largely responsible for the NO x increases, but pure FT diesel produced lower NO x emissions than expected on the basis of SOI alone. Further analysis showed that no trends were seen between NO x and either ignition delay or maximum cylinder temperature, and only weak, or fuel-specific, relationships were seen between NO x and maximum heat release rate and the timing of maximum heat release rate. The timing of the maximum cylinder temperature, however, did produce a relationship with NO x emissions that was not dependent on fuel type.

Performance Evaluation of Palm Oil-Based Biodiesel Combustion in an Oil Burner

“…Lapuerta et al [6] reported that lower emissions of soot, carbon monoxide (CO) and carbon dioxide (CO 2 ), but higher nitrogen oxides (NO x ), were achieved by using biodiesel in a diesel engine. Szybist et al [7] pointed out that compared to conventional diesel fuel (CDF) at high load, biodiesel blends generate 6%-9% higher NO x emissions. For gas turbine engines, Sequera et al [8] investigated the emissions of diesel and biodiesel using swirl burner gas turbine engines.…”

Biodiesel and FAME synthesis assisted by microwaves: Homogeneous batch and flow processes

“…Biodiesels are biodegradable and non-toxic and have lower CO and hydrocarbon emissions than petroleum-based diesel when burned [6,7]. They present, however, other technical challenges such as low cloud points and elevated NO x emissions [8].…”

Production of Biodiesel from Locally Available Spent Vegetable Oils

“…The oil, methanol, and KOH mixture was stirred for 120 min at 60-70C and 400 rpm. The trans-esterification reaction was carried out for different ratios of oil to methanol (10,15,20,30, and 40g). The amount of catalyst had a pronounced influence on the conversion to esters.…”

“…The degree of un-saturation of methyl esters affects the carbon to hydrogen ratio which is slightly different from conventional diesel fuel. The oxygen content is the important difference between conventional diesel fuel and biodiesel because biodiesel contains 10-12 wt% oxygen [13,14,15]. The burning efficiency of biodiesel is improved due to its high oxygen content; thus, it corresponds to lower particulate matter (PM), carbon monoxide (CO), and hydrocarbon (HC) emissions, however, and it produces higher NOx emissions [16].…”