Paper Title
Analysis of Mechanical and Thermal Stresses on Connecting Rod/Piston of a Variable Compression Ratio Engine Powered by Biodiesel
Abstract
Use of alternative fuels in internal combustion engines has become a prime interest for researchers and
industrialists as the conventional fuels continue to have higher costs and bigger impact on the environment. However, not
too many research works address the analysis of mechanical and thermal stresses in essential components of engines running
on alternative fuels. In this work, the fairly new engine technology, Variable Compression Ratio, powered by the alternative
fuel biodiesel is considered in terms of the analysis of mechanical and thermal stresses on the connecting rod/piston.
Modelling the performance of a biodiesel-powered VCR engine using available software in addition to the modelling the
stresses induced on the piston/connecting rod for a variable stroke engine powered by biodiesel using finite element analysis
(FEA) software is presented in this work. Experimental work was carried out where biodiesel was injected in a diesel engine
and the values of the power and torque were monitored using appropriate measuring devices. Verification of the work was
then carried out using special software (Diesel RK) by simulating the same test with similar engine specifications and engine
conditions. Temperature and pressure values where then obtained from Diesel RK and applied as boundary conditions in the
finite element analysis simulation on the piston and connecting rod. Results showed that using biodiesel fuel increases both
the mechanical and thermal stresses in the piston and connecting rod at an earlier stage of the engine stroke due to the
characteristics of biodiesel when compared to diesel fuel; this increase in stresses reduces the lifetime of the piston and
connecting rod which affects the engine on the long run. Furthermore, an increase in compression ratios results in higher
values of stress for both types of fuel. These are significant findings for the industry which indicate that modifications to the
engine operation are necessary to reduce stresses on these main engine components.
Keywords - Biodiesel, Modelling, Variable Compression Ration, stresses, Finite Element Analysis