Numerical modeling of multi-component fuel spray evaporation process O. Samimi Abianeh a , C.P. Chen b,⇑ , S. Mahalingam a a Department of Mechanical and Aerospace Engineering, The University of Alabama in Huntsville, Huntsville, AL 35899, United States b Department of Chemical and Materials Engineering, The University of Alabama in Huntsville, Huntsville, AL 35899, United States article info Article history: Received 2 August 2013 Received in revised form 4 October 2013 Accepted 5 October 2013 Available online 30 October 2013 Keywords: Spray droplet evaporation Droplets collision Multi-component fuel Diesel spray abstract The overarching goal of this study is to implement computationally effective models that can predict the evaporation of multi-component fuel droplets/spray using a multidimensional Computational Fluid Dynamics (CFD) code. The new approach for modeling heat and mass transfer inside a droplet accounts for finite thermal conductivity, finite mass diffusivity, and turbulence effects within the atomizing liquid droplet/spray for multi-component fuel droplet evaporation. This model was developed and validated against experimental measurements for single droplet vaporization and one-way evaporating sprays pre- viously, and is implemented into CFD code for two-way coupled numerical modeling study in this research. A new coalescence model for droplets with different mixture composition was also imple- mented into CFD code in this research. Thereby, the evaporation of multi-component diesel fuel surrogate spray in hot gas environment was predicted and compared with available experimental measurements. The model shows good predictive capability and was demonstrated to improve the accuracy of multi- phase flow simulations. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction In liquid fueled combustion systems such as gas turbine com- bustors, gasoline direct injection, and diesel engines, combustion performance depends strongly on the fuel type, liquid atomization, spray vaporization, and mixing process. Droplet size history during evaporation in a combustion chamber influences the dynamic behavior of droplets, while the variation of the gas-phase composi- tion determines the distribution of the fuel compounds within the combustion chamber. Thus, a fundamental understanding of these processes is essential for modeling evaporating fuel sprays. High pressure injectors, e.g., fuel line pressure of 400–1800 bars for diesel engines and 30–200 bars for Gasoline Direct Injection (GDI) engines, are utilized extensively to accomplish better and ra- pid air-fuel mixing. The fuel atomization process is influenced by a number of parameters, such as fuel property, injector geometry, combustion chamber gas density, fuel injection pressure, etc. Opti- mization of these parameters could lead to cleaner and more stable combustion. Real fuels are typically composed of hundreds of complex com- pounds with different physical properties. In order to comprehen- sively model multi-component fuel evaporation process, it is critical to include the effects of several important thermo-physical processes. These include diffusion of components both inside the droplet and on the gas side, heat transfer inside of the droplets, effects of components on each other, and non-ideality of the mixture. Thus, the evaporation of multi-component droplets is a complex process. In next section, the current state of knowledge associated with droplets/spray evaporation, droplet breakup, and droplets collision as relevant to the present paper is reviewed. 2. Literature review There are several books, papers, and reports dealing with drop- let evaporation, e.g., [3]. Most models for fuel sprays deal with sin- gle component fuels. Fuels are usually characterized by a single surrogate component in most evaporation models implemented in commercial and research computational fluid dynamic codes. However, single-component fuel models are insufficient to predict the complex behavior of complex fuels such as gasoline and diesel [4]. For predicting real fuel evaporation behavior, a method in which surrogate fuels are introduced can be used instead [5]. Sur- rogate mixtures are designed specifically to enable a reasonably accurate numerical simulation of complex mixtures using a small number of components. A multi-component fuel modeling approach can increase the accuracy of prediction of evaporation rate, engine emissions, and overall engine performance, in contrast to single-component fuel modeling. Multi-component fuel models are classified into two types: Discrete Multi-Component models (DMC) and Continuous Multi-Component models (CMC). Studies have been performed on discrete multi-component fuel vaporization, e.g., Ra and Reitz 0017-9310/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2013.10.007 ⇑ Corresponding author. Tel.: +1 (256)824 6194; fax: +1 (256)824 6839. E-mail address: chenc@uah.edu (C.P. Chen). International Journal of Heat and Mass Transfer 69 (2014) 44–53 Contents lists available at ScienceDirect International Journal of Heat and Mass Transfer journal homepage: www.elsevier.com/locate/ijhmt