Abstract
•Thermal barrier coating was accomplished by coating the engine components with PSZ.•Under-utilized kapok oil biodiesel was used as renewable fuel in a coated engine.•The BTE of the engine was improved by 9% with reduced BSFC.•CO, HC and smoke were reduced by 40%, 35.3% and 21.4%, respectively.•After implementing SCR assembly, the NOX emission was decreased by 13.4%.
This research work has been formulated to reduce the stinging effect of NOX emission on atmospheric environment from a coated diesel engine fueled by biodiesel. As such, in the current study, we attempted to harness the renewable source of energy from in-edible kapok oil, which is normally under-utilized despite being a viable feedstock for biodiesel synthesis. Notably, steam treatment process followed by crushing of the kapok seeds in a mechanical expeller was done to extract large quantities of kapok oil for the application of diesel engine, which is quite distinct of a method adopted herein. The conventional trans-esterification process was availed to synthesize KME (kapok methyl ester) and the physical and thermal properties of it were estimated by ASTM standard methods. Subsequently, two blends of KME with diesel such as B25 (KME – 25% and diesel – 75%) and B50 (KME – 50% and diesel – 50%) were prepared and tested in a single cylinder diesel engine with thermal barrier coating. To help realize the coating process, PSZ (partially stabilized zirconia), a pertinent coating material in respect of its poor thermal conductivity and better durability, has been chosen as the coating material to be applied on engine components by plasma spray coating technique. As an outcome of the coating study, B50 was found to show improved BTE (brake thermal efficiency) than that in an uncoated engine, with notable decrease in major emissions such as HC (hydrocarbon), CO (carbon monoxide) and smoke. However, due to reduction in heat losses and increase in in-cylinder temperature, the NOX (oxides of nitrogen) emission was expected to be increased in a coated diesel engine. Therefore, in order to reduce the NOX emission, urea based SNCR system was incorporated in the exhaust pipe and by which, NOX emission was reduced.