Case Studies in Thermal Engineering (Nov 2023)
Performance evaluation of a diesel engine fueled with Chlorella Protothecoides microalgal biodiesel
Abstract
The main objective of the current study is to determine the engine performance, combustion, and emission analysis of compression ignition engines fuelled with Chlorella Protothecoides microalgal biodiesel (CPMB). The biodiesel was derived from Chlorella Protothecoides microalgal oil (CPMO) through transesterification. Under the specified conditions, which included a methanol-to-oil molar ratio of 7.41 (vol/vol), a reaction time of 105.6 min, a reaction temperature of 65 °C, and a catalyst concentration of 1.024 (% wt/vol) and achieved a biodiesel yield of 98.1%. The fuel properties were determined using standard methods, revealing that the density and kinematic viscosity of CPMB were significantly higher than those of diesel. However, CPMB still exhibits satisfactory fuel properties that meet most biodiesel specifications. CPMB boasts a low cloud point (CP) and pour point (PP) of 0 and -3 °C, respectively, indicating its effective usability in cold climates. The oxidation stability of CPMB, determined by the modified Rancimat method, was found to be 4.6 h, satisfying ASTM specifications. The fuel tested in this study was 20% biodiesel with diesel, 100% biodiesel, and neat diesel. These fuels had been tested on a CI engine in which the engine speed and compression ratio were fixed at 1500 rpm and 18:1, respectively. Based on the results, it is found that the indicated thermal efficiency decreases up to 3.68% and 8.22% with B20 and B100 as compared to diesel. However, mechanical efficiency, volumetric efficiency, and indicated power were estimated to be higher at peak engine load conditions when correlated with neat diesel. Furthermore, the mean effective pressure for B20 and B100 was estimated to be decreasing while the mass fraction of fuel burnt and the rate of pressure rise increased compared to diesel at peak load conditions. For exhaust emission analysis, a significant reduction was recorded in CO and UHC emissions, while NOX emission increases at peak engine loads. From the above results, it is accomplished that the performance of B20 blends is nearly identical to diesel, and it can be recommended to be used in engines without any modification.
