Thermophysical properties validation for soy methyl ...

BIOFUELS, 2016 http://dx.doi.org/10.1080/17597269.2016.1187542

Thermophysical properties validation for soy methyl ester biodiesel through experimental spray data Ehsan Tootoonchi and Gerald J. Micklow

Downloaded by [Ehsan Tootoonchi] at 12:54 09 June 2016

Mechanical and Aerospace Engineering Department, Florida Institute of Technology, Melbourne, USA

ABSTRACT

ARTICLE HISTORY

The scarcity of experimental data for soy biodiesel fuel properties covering the full temperature range from injection to critical temperature reduces the reliability and accuracy of fuel property estimation techniques, and hence engine simulations. This study reviews and validates soy biodiesel fuel property estimation techniques indirectly using experimental spray data utilizing a modified version of KIVA-3V computer code. The effect of each estimation technique on spray penetration was investigated through several runs, and one set of fuel property models capable of predicting accurate liquid length for soy biodiesel is presented. The results showed in some cases a significant difference in estimation techniques available in literature with the highest discrepancy found in enthalpy calculations. The results also showed that a higher average fuel particle temperature will result in smaller spray penetration and that estimation techniques can be compared using their effect on average particle temperature. Comparing calculated spray penetration results with experimental values showed that almost all cases tend to overestimate the liquid length with some extreme cases predicting wall impingement.

Received 5 February 2016 Accepted 4 April 2016

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Nomenclature a; A; b; B; C; D Cp0 Cpl f ð0Þ ; f ð1Þ ; f ð3Þ m n M M j ; Nk

PvPr ½P R SMR T Tbr Tr Tc W w1k; w2j K; x; y; z; Δa, Δb; Δc, Δd ΔHv hl r

empirical coefficients ideal gas heat capacity, cal/ mole K liquid specific heat, cal/mole K functions in Pitzer correlation empirical temperature exponent exponent molecular weight, g/mole number of groups of type K in a molecule; Nk for First-Order groups in all methods and Mj for Second-Order groups vapor pressure, bar parachor of component gas constant, cal/mole K Sauter mean radius absolute temperature, K reduced temperature at boiling point (Tb =Tc Þ reduced temperature (T/Tc) vaporliquid critical temperature, K weight for SecondOrder groups first-order and second-order group Contributions empirical coefficients group contribution parameters latent heat of vaporization, J/g liquid viscosity, cp liquid density, g/cm3

CONTACT Ehsan Tootoonchi

etootoonchi2011@my.fit.edu

© 2016 Informa UK Limited, trading as Taylor & Francis Group

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KEYWORDS

Numerical simulation; soy biodiesel; thermophysical properties; liquid length; validation; experimental spray data

liquid density of fuel at normal boiling point, mole/ml surface tension, dynes/cm 1  Tr acentric factor exponent

Introduction Lower values for carbon monoxide, unburned hydrocarbon and particulate matter emissions along with their renewability make vegetable oil methyl esters, or biodiesel, an interesting alternative fuel source all around the world. The downsides of using biodiesel, including lower energy content, higher NOx emissions, and different spray behavior compared to regular petroleum diesel, resulted in far less biodiesel production than its real potential. For instance US biodiesel production was 1268 million gallons in 2015 (4.9% of its capacity in 2015, total of 25.8 billion gallons) [1] which shows the need for more studies and investigations to address shortcomings and present solutions. Accurate modeling of an engine’s combustion chamber sequential events is a complicated task; from modeling fuel thermophysical properties to spray modeling, combustion and emission production all should be separately verified using related experimental data. While each step has its effect on overall reliability and accuracy of the results, accurate fuel property modeling affects all other downstream events