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.

Biodiesel is one of the alternative fuels which is renewable and environmentally friendly and can be used in diesel engines with little or no modifications. In the present study, experimental investigations were carried out on the effects of biodiesel types, biodiesel fraction and physical properties on the combustion and performance characteristics of a compression ignition (CI) engine. The experimental work was conducted on a four-cylinder, four -stroke, direct injection (DI) and turbocharged diesel engine by using biodiesel of waste oil, rapeseed oil and corn oil and normal diesel. Based on the measured parameters, detailed analyses were carried out on cylinder pressure, heat release rate and brake specific fuel consumption (BSFC). It has been seen that the biodiesel types do not result in any significant differences in peak cylinder pressure and BSFC. The results also clearly indicate that the engine running with biodiesel have slightly higher in-cylinder pressure and heat release rate than the engine running with normal diesel. The BSFC for the engine running with neat biodiesel was higher than the engine running with normal diesel by up to 15%. It is also noticed that the physical properties of the biodiesel affects significantly the performance of the engine.

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Biodiesel is one of the most promising renewable, alternative and environmentally friendly biofuels that can be used in diesel engine without any need for any modification in the engine. However, researchers have reported that the engines running with biodiesel emit NOx in higher concentrations. To address this problem, in the present study an experimental investigation has been carried out on the combustion, performance and emission characteristics of a compression ignition (CI) engine running with biodiesel under steady state conditions with a novel NOx reducing mechanism involving a water injections system. The experimental work has been conducted on a four-cylinder, fourstroke, direct injection (DI) as well as turbocharged diesel engine. In this investigation, biodiesel (produced from the rapeseed oil by transesterfication process) has been used.During the experiments the in-cylinder pressure, specific fuel consumption, water injection flow rate, fuel flow rate and exhaust emission (NOx, CO, CO 2 and THC) were measured. The experimental results clearly indicate that water injection at a rate of 3kg/h results in the reduction of NOx emission by about 50% without causing any significant change in the specific fuel consumption. Furthermore, the water injection in the intake manifold has little effect on the in-cylinder pressure and heat release rate of the CI engine under different operating conditions. 2

This paper presents a novel technique for measuring the local axial, radial and azimuthal velocity components of the gas in bubbly gas–liquid flows using a local four-sensor conductance probe. A mathematical model is presented showing how the velocity vector of a gas bubble can be calculated from seven time intervals taken from the output signals from each of the four conductance sensors located within the probe. The paper goes on to describe the construction of a local four-sensor probe and the associated electronic measurement circuitry. Results are presented showing the distributions of the mean local axial, radial and azimuthal gas velocity components in vertical, bubbly gas–liquid flows, both with and without swirl. These results were obtained using the four-sensor probe in a vertical 80 mm diameter pipe into which a swirl generator could be installed. Additional results are presented showing the local gas volume fraction distribution, also obtained from the probe, in bubbly gas–liquid flows with and without swirl. It was found, as expected, that the presence of swirl caused a significant increase in the magnitude of the measured azimuthal velocity of the gas, particularly at the pipe walls. It was also found that, at a comparatively high water flow rate, the presence of swirl caused the gas bubbles to preferentially accumulate at the centre of the pipe.