Remote or off-grid communities in Canada and across the world heavily rely on diesel-fueled generators to meet their electrical power and heating needs. Reducing diesel consumption of these generators with locally produced sustainable fuels such as syngas has the double benefit of reducing the greenhouse gas (GHG) emissions and the cost of transporting diesel to remote locations. In remote/off-grid areas, syngas can be produced from local biomass or waste through gasification or pyrolysis. The aim of this study was to investigate the combustion and emission performance of a syngas-diesel dual-fuel generator at a constant load condition under varying syngas flow rate and composition.
This experimental study was carried out using a 30-kilowatt (kW) generator with a four-stroke, four-cylinder, turbo-charged, and electronically controlled direct injection diesel engine. The intake manifold of the engine was modified to introduce syngas upstream of the engine’s turbocharger. Syngas was simulated using individually controlled flow rates of carbon monoxide (CO), hydrogen (H2), carbon dioxide (CO2) and nitrogen (N2) from compressed gas cylinders before their mixing and introduction into the engine intake manifold. Two practical syngas compositions with varying CO/H2 ratios were evaluated. The engine was operated with a programmable engine control unit to control the diesel direct injection events. Electrical load on the generator was controlled by a load bank set to 11 kW (5.25 bar IMEP) and the engine speed was 1800 rpm.
The experimental results revealed that increasing the syngas flow rate at a fixed diesel injection timing and duration caused the indicated thermal efficiency (ITE) of the engine to decrease. NOx emissions decreased with increasing syngas flow rate but CO, particulate matter (PM) and CO2 emissions increased. Increasing the CO/H2 ratio in the syngas caused the ITE to decrease and the CO and CO2 emissions to increase. The laminar flame speed (LFS) and ignition delay (ID) of syngas-air mixture were calculated to develop a further insight into the experimental results.