Investigations on Reactivity Controlled Compression Ignition Combustion with Different Injection Strategies using Alternative Fuels Produced from Waste Resources

Reactivity-controlled compression ignition (RCCI) is a promising low-temperature combustion (LTC) strategy that results in low oxides of nitrogen (NOx) and soot emissions while maintaining high thermal efficiency. At the same time, RCCI leads to increased unburned hydrocarbon (HC) and carbon monoxide (CO) emissions in the exhaust, particularly under low loads. The current work experimented novel port-injected RCCI (PI-RCCI) strategy to overcome the high unburned emission limitations at low load conditions in RCCI. PI-RCCI is a port injection strategy in which low-reactivity fuel (LRF) is injected using a low-pressure injector, and the high-reactivity fuel (HRF) is injected through a high-pressure common rail direct injection (CRDI) injector. The low volatile HRF is injected into a heated fuel vaporizer maintained at 180°C in the intake manifold during the suction stroke. Modifying a singlecylinder, light-duty diesel engine with the necessary intake and fuel injection systems allows engine operation in both RCCI and PI-RCCI modes. Alternative fuels from waste resources such as waste cooking oil biodiesel (WCO) and plastic waste oil (WPO) are used as the HRF and LRF fuel in RCCI and PI-RCCI. To achieve maximum thermal efficiency in RCCI, the premixed energy ratio and the start of injection of the direct-injected fuel are optimized at all load conditions. The engine performance and exhaust emissions characteristics in PI-RCCI are compared with RCCI as a baseline reference. The results show a 70% and 48% reduction in CO and HC emissions, respectively, in PI-RCCI than in RCCI. Further, the brake thermal efficiency (BTE) was enhanced by around 20%, and the brake-specific fuel consumption (BSFC) was reduced by 13% in PI-RCCI. The NOx emissions decreased without any considerable changes in soot emission in PI-RCCI. The current study shows that fuels derived from waste resources can be used in RCCI and PI-RCCI modes with better engine performance and lower emissions

Production of biofuel from AD digestate waste and their combustion characteristics in a low-speed diesel engine

Anaerobic digestion biogas plants generate large amounts of digestate that cannot always be valorised as fertilizer. This study proposes an alternative use through pyrolysis of the digestate for the production of liquid fuels for compression ignition engines. The digestate pyrolysis oil (DPO) and two types of biodiesel were produced and mixed with different alcohols. A total of five blends of DPO, biodiesel and alcohol were prepared and characterized, showing that their acidity and viscosity were higher than for pure diesel, and their heating value was lower. Blends containing 60 % biodiesel, 20 % DPO, and 20 % butanol were then tested in an engine, showing that the maximum in-cylinder pressure and heat release rate were 4.6 % and 3 % lower, respectively, compared to diesel, and the engine thermal efficiency at full load was 6–8% lower. The nitric oxide and smoke emissions were 7 % and 40 % lower, respectively, but the carbon dioxide emissions were 7–10 % higher than with diesel. The blends showed retarded start of combustion by 1.5° crank angle, which delays the ignition by about 6.4 %. This study concludes that blends can be used as a fuel for agriculture and marine diesel engines, although their viscosity should be reduced by improving the pyrolysis conditions

Plastic waste to liquid fuel: A review of technologies, applications, and challenges

One of the most promising approaches for converting waste plastics into oil is fast pyrolysis. This study reviews the current state of the art and recent progress made on the thermal conversion of plastic to oil technologies, and their uses as alternatives to fossil fuels. The fuel properties of waste plastic pyrolysis oil (WPPO) are close to the diesel fuel. The WPPO produced from high-density polyethylene, low-density polyethylene, polypropylene, and polystyrene have higher heating values ranging from 40 to 43 MJ/kg. The thermal efficiency of neat WPPO (or blends) was slightly lower than diesel or gasoline. The WPPO has a shorter ignition delay than diesel due to its high cetane number. The WPPO fuels have a lower peak in-cylinder pressure and heat release rate than diesel. Engine-out emissions such as smoke, CO, and CO 2, are lower than diesel. The NO x emissions are higher than diesel, which can be reduced with exhaust gas recirculation or use of additives. Our study reveals that the WPPO is a promising alternative fuel for diesel engine applications

A generic controller for managing TCP transfers in IEEE 802.11 infrastructure WLANs

In this paper, we present a generic controller that ensures fair and efficient operation of IEEE 802.11 infrastructure wireless local area networks (WLANs) with multiple co-channel access points. Our controller addresses performance issues of long-lived TCP transfers in multi-AP WLANs, by overlaying a coarse time slicing scheduler on top of a cascaded fair queuing scheduler. The time slices and queue weights, used in our controller, are obtained from the solution of a constrained utility optimization formulation. A study of the impact of coarse time-slicing on TCP is also presented in this paper. We also present a methodology to improve the performance of co-existing short-lived and interactive TCP flows. Finally, we report the results of experiments performed on a real testbed, demonstrating the efficacy of our controller

Preparation and characterization of alumina membranes by anodic oxidation of aluminium

161-164<span style="font-size:11.0pt;line-height:115%; font-family:" calibri","sans-serif";mso-ascii-theme-font:minor-latin;mso-fareast-font-family:="" "times="" new="" roman";mso-fareast-theme-font:minor-fareast;mso-hansi-theme-font:="" minor-latin;mso-bidi-font-family:arial;mso-ansi-language:en-us;mso-fareast-language:="" en-us;mso-bidi-language:ar-sa"="">Inorganic membranes of alumina have been prepared by anodic oxidation of aluminium. The kinetics of the growth of alumina layer in phosphoric acid has been studied at four different temperatures, viz., 20, 30, 40 and 50<span style="font-size:11.0pt; line-height:115%;font-family:" calibri","sans-serif";mso-ascii-theme-font:minor-latin;="" mso-fareast-font-family:"times="" new="" roman";mso-fareast-theme-font:minor-fareast;="" mso-hansi-theme-font:minor-latin;mso-bidi-theme-font:minor-latin;mso-ansi-language:="" en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">ᵒC. The coating ratio, coating thickness, and weight of alumina formed at different time intervals, have been measured. The effect of formation current on the coating thickness has been elucidated. Separating the alumina layer from metal by specifically dissolving the later in bromine and methanol mixture, the surface structures of the oxide layer has been studied by scanning electron microscopy.</span