Date of Award


Degree Type


Degree Name

Master of Science in Mechanical Engineering (MSME)


Mechanical Engineering

First Advisor

Peter H. Meckl

Committee Chair

Peter H. Meckl

Committee Member 1

Patricia Davies

Committee Member 2

Gregory Shaver


A number of factors are responsible for an increased interest in alternative fuels for transportation and other uses. Among the most widely available alternative fuels are biodiesel and vegetable oil, both of which can be used to power a diesel engine. Biodiesel has higher density, viscosity, surface tension, sound velocity, and bulk modulus of elasticity than regular diesel fuel. This affects the fuelling, injection timing, and fuel spray and consequently the emission characteristics.

Estimation of fuel type is critical to the performance of the engine. Knowing the fuel type allows the engine controller to determine the proper fuel quantity and timing to provide the best balance of performance, emissions and fuel economy. Based on the fuel type, the calorific value will change. Knowing this, the engine controller can use the best air-fuel mix, compression, and injection pressure for that type of fuel. Fuel injection characteristics depend on both the type of injection system and the fuel properties. Fuel density, viscosity, sound velocity and bulk modulus of elasticity influence the injection characteristics significantly.

The objective of this project is to estimate whether the fuel is diesel or biodiesel by identifying these critical parameters that characterize a fuel and devising suitable strategies to detect these parameters to determine the fuel type. Using sensors available on the XPI fuel system, this is accomplished by observing the differences that bulk modulus changes between the fuels have on pressure rise associated with pumping events. In the future, we also hope to be able to differentiate between different diesel and biodiesel blends.