Prediction models for density and viscosity of biodiesel and their effects on fuel supply system in CI engines

Abstract

Biodiesel is a promising non-toxic and biodegradable alternative fuel used in the transport sector. Nevertheless, the higher viscosity and density of biodiesel poses some acute problems when it is used it in unmodified engine. Taking this into consideration, this study has been focused towards two objectives. The first objective is to identify the effect of temperature on density and viscosity for a variety of biodiesels and also to develop a correlation between density and viscosity for these biodiesels. The second objective is to investigate and quantify the effects of density and viscosity of the biodiesels and their blends on various components of the engine fuel supply system such as fuel pump, fuel filters and fuel injector. To achieve first objective density and viscosity of rapeseed oil biodiesel, corn oil biodiesel and waste oil biodiesel blends (0B, 5B, 10B, 20B, 50B, 75B, and 100B) were tested at different temperatures using EN ISO 3675:1998 and EN ISO 3104:1996 standards. For both density and viscosity new correlations were developed and compared with published literature. A new correlation between biodiesel density and biodiesel viscosity was also developed. The second objective was achieved by using analytical models showing the effects of density and viscosity on the performance of fuel supply system. These effects were quantified over a wide range of engine operating conditions. It can be seen that the higher density and viscosity of biodiesel have a significant impact on the performance of fuel pumps and fuel filters as well as on air-fuel mixing behaviour of compression ignition (CI) engine.

LHV predication models and LHV effect on the performance of CI engine running with biodiesel blends

“…The heating value was measured using the standard DIN 51900 procedures, summarised in Table 2. The density and viscosity of the biodiesel were also measured by the authors, using the EN ISO 3675:1998 and EN ISO 3104:1996 standards and these results are reported in an earlier publication [20]. …”

“…The blends were made in mixing tank with 10%, 20%, 50%, 75% and 100% biodiesel content by volume. The main physical properties such as composition, density, lower heating value (LHV) and viscosity of the rapeseed oil biodiesel were measured according to the official test standards in EU and the results were published by Tesfa et al [20]. The blends properties are presented in Table 5.…”

“…Many researchers have reported the heating value of fuel measured using experimental testing (using adiabatic bomb calorimeter, proximate and ultimate analyses) [8], [14], [15], [18]- [20]. These conventional analysis methods are complicated, time consuming and require specialised set-up, measurement and calculation procedures [8].…”

Effects of Biodiesel Blend on Marine Fuel Characteristics for Marine Vessels

“…Grun-Nissan viscosity equation applied by Tesfa et al [13] is taken to compute the kinematic viscosity of the blended fuel, which is given below:…”

“…The kinematic viscosity of the blended marine fuel with biodiesel is calculated by a Grun-Nissan viscosity equation [13]. As shown in Figure 3, the blending of residual marine fuel with biodiesel can significantly reduce its kinematic viscosity so that much less heating or pumping energy is required.…”