Abstract:
Despite diesel engines being highly efficient, with low fuel consumption and
reduced carbon dioxide emissions, they emit relatively high levels of particu
late matter and oxides of nitrogen (NOx) due to high exhaust gas tempera
tures. Engine emissions show the quality and completeness of combustion.
This paper aims to present the results of a study comparing exhaust emissions
from a diesel and syngas powered engine. Syngas was produced from co-firing
coal and biomass in a gasifier then cleaned, cooled and applied as an alterna
tive fuel in an engine operated from 0 - 100% load. Exhaust-emissions were
monitored at this load conditions. The exhaust-temperature was measured
using thermocouples and the emission gases were analyzed using Testo 350.
The emissions were lower and decreased as the engine load increased, except
for sulphur dioxide and NOx. The study shows that levels of carbon monox
ide, were higher in a range of 46.5 - 80.2%, while carbon dioxide was 3.3 -
18% higher compared to those from diesel. Hydrocarbon emissions were 480
and 1250 ppm for diesel and syngas respectively. The study reveals that the en
gine operates optimally at higher loads since hydrocarbons and oxides of car
bon are low due to complete combustion at higher temperatures. Exhaust gas
temperature was higher in the syngas fuel and increased as the engine load
increased in the range of 455.83 - 480.03˚C which influenced the formation of
NOx. NOx from diesel was found to be higher, ranging from 32.5 - 40.5%,
compared to those from syngas with an engine load of 75%. The study observed
that relative to diesel, the emissions of sulfur dioxide at 50% engine load were
lower in a range of 23.7 - 57.1%. Emissions of hydrocarbons depended on the
degree of substitution of diesel and engine load. The study therefore shows
that, relative to diesel, emissions decreased when syngas was used with up
DOI: 10.4236/jpee.2024.128003 Aug. 16, 2024
30
Journal of Power and Energy Engineering
B. Kariuki et al.
graded syngas from Prosporis juliflora presenting as the best alternative fol
lowed by Hyphanae compressa, and lastly rice husk. For optimal performance
of the syngas fuelled engine, the study reports that the engine should be oper
ated at engine loads above 50% with strategies on NOx emissions considered.
