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

Authors: E.I. Onuh; Freddie L. Inambao

Addresses: School of Engineering, University of KwaZulu-Natal, Durban, South Africa ' School of Engineering, University of KwaZulu-Natal, Durban, South Africa

Abstract: Oxides of nitrogen (NO_x) 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. NO_x 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.

Keywords: pure biodiesel; Zeldovich mechanism; dissociation; exhaust gas recirculation; EGR; low temperature combustion; LTC.

DOI: 10.1504/IJGW.2018.088643

International Journal of Global Warming, 2018 Vol.14 No.1, pp.21 - 39

Received: 18 Jul 2015
Accepted: 27 Dec 2015
Published online: 14 Dec 2017 *

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