Experimental analysis of the influence of urea injection upon NOx emissions in internal combustion engines fueled with biodiesels

• The effect of urea injection on NOx emissions in a biodiesel fueled diesel engine shows a decrease in NOx production.
• By increasing injection temperature, the NOx emissions amount is reduced.
• Increasing urea mass flow rate results in more reduction of NOx emissions.
• Lower NOx emission has been reported by increasing injection angle.
• Increasing the number of nozzles leads to drop in NOx emissions.

The effect of urea injection on NOx emissions in a six-cylinder, four-stroke internal combustion engine fueled with B80 biodiesel has been experimentally investigated. The results reveal that urea injection leads to a reduction of NOx emissions of B80 biodiesel fuel. Moreover, the influence of injection parameters on NOx reductions has been studied. The findings show that increasing the injection temperature results in lower NOx emissions. Also urea mass flow rate increment leads to more NOx reduction. The same result has been obtained by an increase in spray angle. In addition, increasing the number of nozzles indicates more depletion in NOx emissions while a “three-nozzles spray system” has the most considerable effect on NOx reductions.