Biodiesel production from waste cooking oil is a potential feedstock to alternative fuel sources. Produced alternative fuel sources were to have a strong emphasis on energy efficiency to substitute the declining world supply of fossil fuels while also improving emission characteristics in diesel engine applications. The development of industrialization and mechanization causes increased fossil fuel consumption and its usage. This study aimed at an experimental investigation of biodiesel blended fuel combustion efficiency for single-cylinder diesel engines under varying engine loads at constant engine speed 1500 rpm. The transesterification process was used to produce biodiesel from waste cooking oil using NaOH as catalysts. Biodiesel reaction takes place with oil to methanol ratio of 6:1 at 60 °C reaction temperature for 90 min with 600 rpm stirring speed while 90% yield gained. Eight sample biodiesel blends were prepared with percentage value B5%, B10%, B15%, B20%, B25%, B30%, B35%, B40% v/v and B100% to investigate the effect of biodiesels on engine performances. The experimental result reveals that the mixed biodiesel blends have lower average value in terms of brake torque, brake power, and brake thermal efficiency than diesel fuels as a percentage of 16.79%, 4.08%, and 27.9% respectively. In addition, the average BSFC of biodiesel blends was increased by 4.8% than baseline diesel fuel. Related to exhaust gases emission test results were shows that the average CO and HC emissions decreased by 52.2% and 60% with increasing loads and blends and the increment of CO₂ and NOx by 28.1% and 45.4% respectively than baseline fuel with increasing blends and loads. Biodiesel derived from waste cooking oil was less costly and environmentally friendly and viable to substitute petro-diesel.

Due to the popularity of diesel engines, utilization of fossil fuel has increased. However, fossil fuel resources are depleting and their prices are increasing day by day. Additionally, the emissions from the burning of petroleum-derived fuel is harming the global environment. This work covers the performance and emission parameters of a biogas-diesel dual-fuel mode diesel engine and compared them to baseline diesel. The experiment was conducted on a single-cylinder and four-stroke DI diesel engine with a maximum power output of 2.2 kW by varying engine load at a constant speed of 1500 RPM. The diesel was injected as factory setup, whereas biogas mixes with air and then delivered to the combustion chamber through intake manifold at various flow rates of 2, 4, and 6 L/min. At 2 L/min flow rate of biogas, the results were found to have better performance and lower emission, than that of the other flow; with an average reduction in BTE, HC, and NOx by 11.19, 0.52, and 19.91%, respectively, and an average increment in BSFC, CO, and CO₂ by 11.81, 1.05, and 12.8%, respectively, as compared to diesel. The diesel replacement ratio was varied from 19.56 to 7.61% at zero engine load and 80% engine load with biogas energy share of 39.6 and 16.59%, respectively.

This paper presents the impact of preheated palm oil methyl ester) (POME) properties and examines the consequences of varying fuel injection pressure (IP), fuel injection timing (IT) and injector nozzle hole number (IJNHN) for improving the combustion quality in a diesel engine, by evaluating the performance parameters, combustion characteristics and emissions. The fuel IPs changed from 188 to 224 bar (with an increment of 12 bar) at fuel ITs 19°, 23° and 27° Before Top Dead Center (BTDC) with a variation of IJNHN (3–5) each 0.3 mm in diameter. The test results revealed that the kinematic viscosity and density of POME decreased slowly with an increase in fuel temperature. At 114 °C, the viscosity and density of POME decreased to close to that of diesel fuel. Preheating POME improved engine brake specific fuel consumption (BSFC), brake thermal efficiency (BTHE) and emissions of CO and Hydro Carbon (HC), with a slight increase of NO_x. The results indicate that increased fuel IP of 212 bar and an advanced IT of 27° BTDC with a four-hole IJNHN for preheated POME (114 °C) was the best combination for overall improvement in BSFC and BTHE with reduced emissions (of CO and HC) with respect to baseline diesel.

In this study, the combined effects of fuel and intake air preheating on the performance, combustion, and emission parameters of a diesel engine running on different preheated blends of fuel are studied. The preheated Palm oil methyl ester (POME) through waste heat exhaust gases is chosen as blended fuel to achieve better fuel injection characteristics. The increase in the fuel-preheated temperature shows the drop in kinematic viscosity and density values of POME. At a fuel preheating temperature of 114 °C, the viscosity and density of POME drop to 3.74 mm²/s and 871 kg/m³ which are closer to values for mineral diesel (3.35 mm²/s at 40 °C and 842 kg/m³ at 27 °C). Preheating optimized POME at inlet temperatures of 90 °C and 102 °C in a diesel engine results in the improvement of the brake specific fuel consumption, brake thermal efficiency (BTHE), and emissions (CO, HC, and CO₂) with a slight increase in NOx compared to unheated POME at varying loads. In addition, preheated intake air at elevated temperature assisted further enhancement of the engine performance, combustion, and reduction of emission parameters of a diesel engine fueled with preheated blends of fuel.

This work covers the impact of varying injector nozzle hole numbers (INHNs) and fuel injection pressures (IPs) on fuel atomization, performance, and exhaust emission characteristics of a diesel engine. The primary goal of this research was to improve fuel characteristics. Increasing INHNs and fuel IPs have a substantial impact on the blended fuel viscosity and density, which leads to increased atomization and mixing rates, as well as combustion and engine efficiency. The fuel atomization was checked by varying the INHNs with an operating diesel fuel using the ANSYS Fluent spray simulation work. The experimental test was performed on the fuel blends of waste cooking oil (WCO)–diesel blends from 10 to 30% (with an increment of 10%) by evaluating the performance and emission parameters. The fuel IPs were altered on four, such as 190, 200 (default), 210, and 220 bar with a modification of INHN of 1 (default), 3, and 4), each 0.84, 0.33, and 0.25 mm in orifice size, respectively. The simulation result shows that the INHN-4 has better fuel atomization. Whereas the experimental test revealed that the increment in blending ratio of WCO was up to 30%, INHNs and fuel IPs enhanced the BSFC and BTE and reduced exhaust emissions. The results indicate that increasing the fuel IP up to 210 bar with a 4-hole INHN for B30 was the optimal combination for the overall enhancement of BSFC and BTE, as well as lower CO and HC emissions with a minor rise in NO_x when compared to the baseline diesel.

Plastics play a crucial role in modern human life. While plastics have versatile applications, they are mainly serving for packing purposes. Many of the plastics used for packaging applications are petrochemical derivatives. Even though they fulfill most of the criteria as good packing materials, they are not biodegradable. This causes serious environmental pollution. As a result, biodegradable plastics have emerged as an alternative to conventional plastics. Polyvinyl alcohol (PVA) is one of the biodegradable polymers that have potential applications for various purposes because of its availability, non-toxicity, and biodegradability. However, high water absorption hinders its application. To overcome this drawback, locally extracted natural biodegradable sisal fiber was used as reinforcement in this report. The sisal fiber was extracted from the sisal plant found in the Ethiopian highlands. After the extraction of the fiber, 10%NaOH was used for treatment to enhance interfacial adhesion between the sisal fiber and the matrix. Sisal fiber reinforced composites with weight percentage of 0%, 5%, 10%, 20%, and 25% sisal fiber with respect to PVA were prepared using the solution casting technique. In addition to this, a cross-linker (boric acid) was used to crosslink PVA chains. The water absorption and degradation of the samples were studied. The result showed that the water absorption PVA was reduced from 170% for pure PVA to 32% for the synergy of 25% w/w reinforcement and 5.68% w/w of cross-linker concentration. The biodegradability study showed that all the samples were degradable. However, both reinforcement and cross-linkers did not show a significant change in the degradation of PVA. The synergy between boric acid cross-linking and natural sisal fiber reinforcement might be responsible for the reduction of water absorption.