The Impact of the Bulk Modulus of Diesel Fuels on Fuel Injection Timing

Abstract

In this paper, we examine the interaction between the bulk modulus of compressibility of various fuel samples and its effect on fuel injection timing. The fuels considered range from soy oilderived biodiesel, unrefined soybean oil, and paraffinic solvents to ultralow-sulfur and conventional diesel fuels. Both the impact on injection timing and the variation in the bulk modulus of compressibility are measured. The present work confirms that the higher bulk modulus of compressibility of vegetable oils and their methyl esters leads to advanced injection timing with in-line pump-line-nozzle fuel injection systems. This has been shown in the literature to contribute to the well-documented increase in NO x emissions with the use of biodiesel fuel. An opposite trend, a retarding of injection timing, is observed with paraffinic fuels, because they have a lower bulk modulus of compressibility than conventional diesel fuels. This supports the observation that paraffinic fuels such as Fischer-Tropsch diesel yield lower NO x emissions.

The effect of injection timing on the performance and emission of direct injection CI engine running on diethyl ether-diesel blends

“…Ignition delay and combustion characteristics are very sensitive to changes in injection timings, as the temperature and pressure changes significantly close to TDC [21][22][23]. The effect of injection timing on the performance and emission of direct injection CI engine running on diethyl etherdiesel blends heat release rate.…”

Temperature and pressure dependence of density of a shale oil and derived thermodynamic properties

“…[35][36][37][38][39] These equations have also been used before by other researchers for calculating the speed of sound or the bulk modulus from density data and vice versa. 40 The experimental density data were fit with a polynomial equation (Equation 6) to describe both the temperature and pressure dependence of the density, and then this equation was used to calculate the necessary partial derivatives. To calculate the heat capacity at the temperatures at which the density data had been measured a linear equation was fit to the experimental heat capacity data (Equations 7 and 8).…”

The Use of Biodiesel in Diesel Engines

“…Biodiesel feedstock does not inherently contain sulphur but however, it may be present in biodiesel because of prior contamination during the transesterification process and in storage (EMA, 2003). Some other physical properties of biodiesel affect characteristics of the combustion in diesel engine such as density and viscosity (Rakopoulos & Hountalas, 1996) and bulk modulus of compressibility (Tat & Van Gerpen, 2002;Boehman et al, 2004). The bulk modulus of compressibility of biodiesel (property not shown in Table 3) is higher than that of fossil diesel.…”

“…The advanced injection timing and increased injection pressure (and thereby increased fuel injection rate) have been frequently reported for the use of biodiesel (Szybist & Boehman, 2003). The main reasons are due to their differences in density (Rakopoulos & Hountalas, 1996) and bulk modulus of compressibility (Boehman et al, 2004). Chuepeng et al (2007) studied quantitative impacts on combustion characteristics and exhaust emissions by the use of high proportion biodiesel blends.…”