4266 This article not subject to U.S. Copyright. Published 2010 by the American Chemical Society pubs.acs.org/EF Energy Fuels 2010, 24, 4266–4276 : DOI:10.1021/ef100496j Published on Web 07/19/2010 Evaluation of the Physicochemical Authenticity of Aviation Kerosene Surrogate Mixtures. Part 1: Analysis of Volatility with the Advanced Distillation Curve Thomas J. Bruno* and Beverly L. Smith Thermophysical Properties Division, National Institute of Standards and Technology (NIST), Boulder, Colorado 80305 Received April 20, 2010. Revised Manuscript Received June 24, 2010 Because of the complexities involved in measuring and modeling the performance and properties of finished fuels, the fuel science community must often use surrogate mixtures as substitutes, especially in the absence of consensus standard mixtures. While surrogate mixtures are often formulated on the basis of the ability of a particular mixture to reproduce a particular property, there is usually a desire to employ surrogate mixtures that are physicochemically authentic. This means that, provided that the primary purpose is satisfied, researchers are inclined to choose mixtures that have physical and chemical properties appropriate to the finished fuel. In this paper, we apply the advanced distillation curve method as a means to evaluate the physicochemical authenticity of surrogate mixtures. While the strategy outlined here can be used for any family of surrogates, we apply it to surrogate mixtures for Jet-A/JP-8. Mixtures were divided into two groups: (1) simple surrogate mixtures with up to three components and (2) complex surrogate mixtures with more than three components. We found that the modified Aachen surrogate (among the simple fluids) and the Schultz surrogate (among the complex fluids) had the best physicochemical authenticity. Introduction The study of finished fuels and their performance in practical engines is necessarily a nontrivial undertaking. Fuels can contain upward of 1000 components (that can be identified), some of which can interact with one another and, thus, affect the properties of the overall mixture. 1 In addition to this complexity, which can be ascribed to each individual batch of fuel, fuels made primarily from petroleum feed stocks by refineries or blenders exhibit a pronounced batch-batch variability in composition that adds to the complexity. 2 Despite this significant chemical ambiguity, the need to optimize the performance of machinery operating with practical finished fuels is not diminished. Current pres- sures for improving efficiency while minimizing environmen- tal damage, the uncertainties in traditional supply sources, and introduction of non-traditional supply sources simply augment the need to deal with these issues. It is and will continue to be vital to measure and model such fundamental properties as the fluid thermophysics and kinetics, as well as engineering properties, such as threshold sooting index (TSI), ignitability, flame relight ability, flame propagation, etc. For some fuels, such as gasoline, reference fluid mixtures have been developed as consensus standards upon which scientists and engineers can develop and perform such pro- perty measurements. 3 The availability of such consensus stan- dard mixtures ensures that all measurements are performed on a well-understood or at least an accepted fuel. Aviation turbine kerosenes are a class of finished fuels for which no set of consensus standard fluids currently exist. This is partially because the requirements of testing protocols for turbine fuels are more diverse; consensus on a detailed set of specifications is simply more difficult to achieve. Moreover, the required knowledge base for some of the components of the real fuel (such as detailed kinetic mechanisms) is often absent. The resulting approach that has been adopted is to test and model surrogate fluids (simpler stand-in mixtures that are more easily characterized) instead of the finished fuel. 4-16 An inherent limitation of this approach is that surrogate mixtures *To whom correspondence should be addressed. E-mail: bruno@ boulder.nist.gov. (1) Edwards, J. T. Advancements in gas turbine fuels from 1943 to 2005. Trans. ASME 2007, 129 (1), 13–20. (2) Smith, B. L.; Bruno, T. J. Improvements in the measurement of distillation curves: Part 4;Application to the aviation turbine fuel Jet- A. Ind. Eng. Chem. Res. 2007, 46, 310–320. (3) Andersen, V. F.; Anderson, J. E.; Wallington, T. 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