61st Annual Report on Research 2016

Nanofuels are liquid fuel dispersions containing metallic or metalloid nanoparticles. The development of nanofuels has great potential impacts on petroleum engineering, clean energy, aerospace engineering, and various chemical and material processing technologies. The fuel-particle mixtures may have better performance compared with the traditional liquid fuels, for examples, higher energy density, faster and easier ignition, enhanced catalytic effect, reduced emission, faster evaporation and burning rate, higher fuel oxidation rate, and thus are capable of enhancing combustion efficiency. However, challenges and problems such as basic understanding and estimation of the thermal physical properties of multicomponent nanofuels, better control of dispersion stability, and the prevention of dry mass formation need to be overcome prior to practical applications. It was found that evaporation alone (without chemical reaction) is already a very complicated problem, which is multiscale, multiphase, and multicomponent, and stongly depends on the interplay of nanoparticles, interfaces, and the relevant heat and momentum transport phenomena. This ACS project has an overarching goal on developing a simplified model system focusing on basic thermal physical properties and evaporation kinetics of multicomponent nanofuels.

The first part of the research consisted of modeling and experimental mesurement of the evaporation kinetics of binary fuel systeem. The precision measurement was carried out by using a quartz crystal resonator. The mathematical formulation, analytical approximation, numerical computation, instrument calibration, and experimental tests were completed by Prof. Fan’s group in University of Connecticut during the project years. The evaporation kinetics of a binary mixture of methanol and 1-butanol was measured by the acoustic waves emitted from a crystal resonator. The stratification of viscosity and concentration were simultaneously measured by impedance analysis through the shear wave near the crystal surface. All measurements were compared with model predictions. The experimental and theoretical details were completed and published in Int. J. Heat & Mass Transfer during the final year of the project, listed in recent publication linked to this report.

The second part is primarily on experimental analyses of the evaporation kinetics and properties of nanofuel droplets, which were carried out by Prof. Qiao’s group in Purdue University. It was found that addition of nanoparticles changes the latent heat of vaporization of water and ethanol based nanofluids. Specifically, Ag and Fe nanoparticles result in a substantial reduction of the latent heat, while Al addition increases the latent heat slightly. By computing the total enthalpy of the system before and after vaporization using molecular dynamics simulations, it was found that the bond strength between nanoparticles and fluid molecules plays the major role for the change of latent heat of vaporization. The details have been published in J. of Applied Physics linked to this report.

Overall three graduate students (two PhD and one MS students) have participated the project during the project years. All students were trained to conduct theoretical and experimental investigations, and were partly supported by this grant. Both the UConn and Purdue groups actively shared the research results. Research assistant positions have been provided to graduate students at UConn and Purdue. The financial support through this ACS PRF seed grant is very much appreciated and acknowledged in all research disseminations including journal papers, proposals, conference and seminar presentations. There is no intellectual property to disclosure for this project.