A comprehensive review of biodiesel property prediction models for combustion modeling studies. (15th October 2021) - Krishnasamy, Anand
Highlights: Models to predict biodiesel properties for combustion modeling reviewed in detail. Based on several statistical parameters best models to predict thermophysical properties of biodiesel suggested. Experimental data base for critical properties of methyl ester constituents of biodiesel need to be developed. To extend the applicability of property prediction models, there is a need to develop experimental data in the high temperature range. Abstract: Among the various alternative fuel options for diesel, biodiesel has emerged as the most promising fuel because of its renewable origin, availability, biodegradability, high combustion efficiency and lower emissions. Although, experimental investigations on biodiesel combustion in different engine types are exhaustive, corresponding numerical investigations are sparse. The underlying mechanisms behind the combustion trends with biodiesel can be better understood through numerical modeling of combustion processes. Further, numerical modeling should be an integral part of engine design and development work with alternative fuels like biodiesel that is subjected to composition variability. Arriving at optimal biodiesel composition for engine applications through experimental measurements is time consuming and laborious and thus, the role of computational fluid dynamic investigation (CFD) is imperative. For biodiesel spray and combustion modeling studies, the liquid and vapor phase thermophysical properties of biodiesel at different temperatures ranging from ambient to critical conditions are required which are impossible to measure experimentally. Thus, there are sustained interests in developing numerical models for predicting thermophysical properties of biodiesel from combustion modeling standpoint. There are various approaches and models developed to estimate the thermophysical properties of biodiesel. In the present review, approaches and models available to estimate the important thermophysical properties of biodiesel including density, viscosity, surface tension, latent heat of vaporization and vapor pressure are comprehensively analyzed using various statistical parameters. Further, available approaches to predict the critical properties which are required for predicting the thermophysical properties of biodiesel are also reviewed. Based on several parameters such as reported deviation, method of validation, simplicity, and applicable range, the most suitable approach and the corresponding model for estimating the thermophysical properties of biodiesel are suggested for spray and combustion modeling studies.