Application of ethanol to gasoline engines may be feasible without any modifications to port fuel injection (PFI) engines. Pure plant oil sprays with potential use in CI engines may require alternative injector technology due to slower breakup as compared to diesel. Evaporating sprays revealed that the liquid length is longer for biodiesel. As far as secondary atomization is concerned, changes in regimes are observed to occur at higher air-jet velocities for biodiesel compared to those of diesel. However, further studies on understanding primary atomization and the effect of fuel properties on primary atomization are required. Results of analytical and computational models are shown to be useful in shedding light on the actual process of atomization. Biodiesel sprays are found to penetrate faster and have narrow spray plume angle and larger droplet sizes compared to diesel. The physics of basic atomization process of sprays from various injectors is included to highlight the most recent research findings followed by discussion highlighting the effect of physico-chemical properties on spray atomization for both biofuels and fossil fuels.
Both experimental and computational research findings are reviewed in a detailed manner for compression ignition (CI) engine sprays and briefly for spark ignition (SI) engine sprays. Spray process being important in IC engine combustion, existing literature on various biofuel sprays is reviewed and summarized. To come up with the optimal solutions, the authors compared various proposed alternative fuels, alongside their advantages and drawbacks with an aim to find the most appropriate role for each fuel.Ever increasing energy requirements, environmental concerns and energy security needs are strongly influencing engine researchers to consider renewable biofuels as alternatives to fossil fuels. In this work, the authors tried to review alternative fuel characteristics, alongside their utilisation and production opportunities. Even though significant increment in biomass consumption raises serious concerns about its sustainability, and seeks for new approaches. Renewable energy source like biomass, on the other hand, is already widely used, and their role in the future system is not questionable. Fuels which can simultaneously be used for power generation and as an energy carrier will have a more important role in the future and are likely to be utilized on a greater scale. This feature might be crucial while discussing their utilisation potential and further development. Another great advantage of some alternative fuels lies in their possibilities to act as an energy carrier.
Most of the alternative fuels that are considered for future applications are already known chemicals or products, nowadays used for other purposes. These electricity surpluses that will occur more often in the future energy system could be effectively utilized for the production of alternative fuels. Higher penetration of intermittent renewable energy sources implies the installation of energy storage, to store electricity excess and enhanced system efficiency. Transition and decarbonization of the energy sector require the utilisation of new technologies and energy sources.