Comparative investigation of crude and waste soyabean oil biodiesel blends in a VCR engine

Abstract

Biodiesel presents itself as a promising and environmentally friendly alternative fuel source, derived from both edible and non-edible oils, attainable through the process of transesterification. This fuel source exhibits the potential for integration into diesel engines, whether with modifications or in their existing state. The impending scarcity of conventional diesel fuel, which carries significant implications, propels biodiesel into a role as a feasible remedy that can offset the adverse impacts on our lifestyle. The creation of biodiesel entails the transformation of waste soybean oil (WSOBD) and crude soybean oil (CSOBD) into a practical fuel solution. The density and viscosity attributes of the resulting biodiesel hold considerable importance, aligning with industry standards. The density and viscosity values for WSOBD fall within the prescribed parameters, whereas those for CSOBD slightly surpass those of WSOBD while maintaining acceptable levels. The evaluation of biodiesel's combustion characteristics involves an analysis of two blends—5% and 10% biodiesel—in conjunction with traditional diesel fuel. This assessment takes place within a four-stroke VCR Diesel engine, under varying load conditions (zero and full). Experiments are conducted at different compression ratios (15 to 18). The investigation focuses on comparing the highest pressures reached during combustion and the values of Net Heat Release. Notably, WSOBD5 displays a slight enhancement in peak pressure when compared to the CSOBD blend under no load conditions. Meanwhile, WSOBD10 surpasses the CSOBD blend in full load conditions. A scrutiny of NHR values between crude and waste biodiesel reveals minor variations. The duration of combustion displays negligible differences between the biodiesel blends, with WSOBD demonstrating a tendency toward superior performance relative to CSOBD. At distinct load points— Zero, 25%, 50%, 75%, and full load—CSOBD5 consistently presents the highest NHRmax values within the realm of crude biodiesel blends, showcasing its robust combustion characteristics. Nevertheless, in multiple scenarios, WSOBD10 maintains a competitive stance by exhibiting commendable NHRmax values. The recorded cylinder pressure for biodiesel blends in relation to crank angle is consistently lower than that of diesel fuel under all load conditions. Particularly noteworthy is the observation that at a compression ratio (CR) of 17, both CSOBD and WSOBD exhibit maximum pressures that closely approach those of diesel. Moreover, at a load condition of 75%, the biodiesel blends demonstrate their most favorable results in this regard. Minor variations in Net Heat Release (NHR) become apparent when comparing the two biodiesel types, crude (CSOBD) and waste (WSOBD). There's an observable pattern of fluctuations as the compression ratio (CR) increases, with some decreases followed by increases in NHR. Notably, at a compression ratio of 17 and under a 25% load, the maximum NHRmax for both CSOBD and WSOBD approaches that of diesel, highlighting their competitive performance in these conditions. The measured peak pressure of biodiesel blend is lower than diesel fuel at all load conditions and increases with at higher CRs. Throughout various compression ratios (CRs), except for CR 15, it is observed nearly identical values for cylinder pressure relative to cylinder volume. However, at CR 17 and CR 18, under a 75% load, the maximum cylinder pressure for both CSOBD and WSOBD closely matches that of diesel, signifying their comparable performance in these specific conditions. When considering Specific Fuel Consumption (SFC), the CSOBD5 blend achieves its highest value at 0.77 kg/kWhr, while at a load of 3, WSOBD5 reaches 0.67 kg/kWhr, at a load of 75%, the CSOBD10 blend records its lowest fuel consumption rate, measuring at 0.17 kg/kWhr and the WSOBD10 blend reaches its minimum fuel consumption rate of 0.05 kg/kWhr when the engine is operating at full load . In terms of Break Thermal Efficiency (BTE), the CSOBD5 blend attains its peak efficiency at 29.73, while WSOBD5 reaches 29.36 under full load and at compression ratio 17. This study underscores the potential of biodiesel, especially that derived from waste soybean oil, as an alluring option due to its promising combustion properties. While distinctions exist between crude and waste biodiesel, both exhibit the capacity to address the mounting apprehensions associated with the depleting supply of conventional diesel. It is evident from the through literature study that waste cooking oil will be a prospective feedstock for biodiesel production specifically for developing nations like India