An evaluation of neat biodiesel/diesel performance, emission pattern of NOx and CO in compression ignition engine

Abstract

Oxides of nitrogen (NOx) and carbon (II) oxide (CO) emissions from engine running on pure biodiesel constitute one of the environmental challenges to its application as fuel. Verifying their sources and production pattern is an essential first step to tackling the challenge. 100% biodiesel derived from moringa, jatropha and waste oil along with petroleum diesel were evaluated in a single cylinder diesel engine. It was observed that oxygen concentration and combustion temperature are the primary drivers of a kinetically determined process. NOx emission trended with Zeldovich mechanism prediction and thus increases with increasing O2 concentration and temperature. CO2 dissociation at elevated combustion temperature in a suppressed O2 concentration regime governs CO production for normal diesel running at high load but, low temperature and high viscosity account for same effect in biodiesel runs. CO therefore increases with increasing temperature and decreasing O2 concentrations for petroleum diesel but for biodiesel, the reverse is the case. Novel exhaust gas recirculation (EGR) and low temperature combustion (LTC) engine therefore holds the key to unlocking biodiesel potential and remediating some of the difficulties observed with petroleum diesel.