SOME STUDIES ON SPRAY CHARACTERISTICS OF ALTERNATIVE FUEL AND THEIR EFFECT ON COMBUSTION, PERFORMANCE AND EMISSIONS

Abstract

At present, India is the fourth chief-importer of petroleum and crude products. Owing to the inadequate resource availability, India chiefly relies on its import, leading to fluidity of its overseas exchange. Abrupt hike in neat diesel fuel within a year in India isn’t well-received in agricultural domain, especially by farmers and agronomists. Over and above, it’s prognosticated that soaring energy requirements would increase petroleum diesel by 6-7% in the impending two decades. Expanded production of WCO causes serious waste disposal issues. In most situations, this waste oil discharges into water bodies. It degrades the water quality, and this contaminated water can cause many health issues. Further, oxygen deficiency in combustion of diesel fuel encourages the carbon emissions. Most of waste oils are generated from edible oils after frying or cooking operations. Approximately 70–80% of the total cost of biodiesel production is associated with feedstock cost, so the cost of biodiesel production could be reduced to 60–70% if waste cooking oil (WCO) is used as feedstock. The use of WCO as a biodiesel feedstock can mitigate issues such as water contamination and drainage systems blockages, which required additional cleaning. It is found to be a highly efficient way to deal with disposal issues with the partial fulfillment of the world’s energy demand. Therefore, the current research exhibits the conversion of waste cooking oil to diesel like fuel through transesterification method and experimental and computational study were performed to study the spray characteristics and combustion characteristics. Further, the study has been carried out in four different phases. The first phase consists of selection and production of biodiesel from waste cooking oil. The reaction parameters such as reaction temperature, reaction time, catalyst concentration and alcohol to oil molar ration were varied to get maximum yield. Where, the optimized parameters were 120min reaction time, 1200C reaction temperature and 1:6 oil to alcohol molar ratio. Then, the approval experiment was performed using above reaction parameter and found 89.5%

conversion efficiency. The physico- chemical properties like density, viscosity, surface tension, calorific value, distillation temperature etc. were estimated and got the value within the limit as per ASTM standards. The second phase of work contains mixing of biodiesel with diesel in different proportions and spray visualization was performed to validate the computational model. the computational study consists of linear instability sheet atomization model and taylor’s analogy and that imparted the acceptable agreement with standard data and the deviation presented was within 5% limit. The grid convergence test was also performed and found to be 1.96 million cells with residual of 10-6 to converge the solution. The results showed that as the injection pressure increases from 110MPa to 160MPa, the spray tip penetration was increases while the spray cone angle decreases with constant ambient pressure. The maximum increase in tip penetration was recorded by 19.86% for B100, while highest decrease in cone angle was seen by 6% for B100, however, the lowest in both conditions is for diesel fuel. The reduction in sauter mean diameter from 110MPa to 160MPa was observed for B25 by 33% followed by B100 and diesel. The third phase of testing consist the determination of rheological properties especially surface tension. Since, the surface tension of biodiesel is depending on production process and also it plays a major role in atomization characteristics and combustion characteristics. The theoretical and experimental investigation on fuels such as soyabean, jatropha, Karanja, Palm, rapeseed, sunflower was done at wide range of temperature. The results showed that Gibbs free model exhibited lowest error1.6-6.8% than Dalton type mass average model (9.52-14.16%) and Macleod – sudgen model (3.2-12.1%) at wide range of working temperature. The modification in double bonds in unsaturated FAME able to improve the accuracy towards standard data. The last phase of investigation is to examine spray combustion characteristics of waste cooking oil (WCO) using swirl nozzle (SN) and conventional nozzle (CN) with same cross-

section area. Surrogates of WCO were used in simulation such as n-heptane, methyl decanoate and methyl-9-decenoate. The computation consists Eularian- Lagrangian approach to emphasize multiphase flow and linearized instability sheet atomization model model, Taylor analogy break up model to identify atomization, film formation and sheet breakup. Further, to identify the model’s strength, validation of spray tip penetration, and kinetic solver for heat release rate and maximum temperature was accomplished against experiment and previous work and that permitted for further investigation at all injection pressures. The cool flame temperature was identified by formaldehyde (CH2O) species, where main ignition was by formation of OH species. The results revealed that evaporative spray tip penetration through SN was little lower than CN at all injection pressures (100 MPa, 200 MPa, 300MPa), however, cone angle was higher for same. Axial and circumferential motion of spray volume exhibited early disintegration of fuel jet and that causes more air entrainment. Generation of OH* has been considered for ignition, lift-off and combustion. SN showed decrease in ignition delay by 3.26%, 4.65% and 8.97% and lift-off length by 1.78%, 5.88% and 8.43% at 100 MPa, 200MPa and 300MPa respectively as compared to CN, and this is due to shorter primary break-up length in SN. An Increment in Heat release rate and Temperature was observed for SN than CN, and also soot was reduced by 3.20%, 4.81% and 6.72% with increase in injection pressure from 100MPa to 300MPa. This is due to better air -fuel mixing through swirl nozzle as compared to conventional nozzle. It was observed that influence of SN became strong with increasing injection pressure because rheological properties of WCO were decreased at ultra-high injection pressures.