Stabilized Nanofluids for Enhanced Combustion Energy

Advanced Cooling Technologies, Inc. utilized the plasma enhanced chemical vapor deposition (PECVD) technique to stabilize (from agglomeration) and passivate (from oxidation) aluminum nanoparticles for dispersion into liquid fuels.  Aluminum has a higher enthalpy of combustion than liquid hydrocarbon fuels.  Thus, dispersing small quantities of aluminum nanoparticles in fuel will increase the enthalpy of combustion of the nanofuel.

However, aluminum quickly forms an aluminum oxide layer in the presence of oxygen, which does not provide any benefits during combustion.  The aluminum needs stabilization from agglomeration and passivation from oxidation in order to utilize the benefits of adding aluminum nanoparticles to the fuel.  Dispersing PECVD coated aluminum nanoparticles at 3.0% by volume in RP-2 fuel exhibited a 0.9% increase in the volumetric enthalpy of combustion (i.e. energy density) compared to baseline RP-2 fuel.  Furthermore, uncoated aluminum nanoparticles at equivalent concentration exhibited marginal improvement indicating depletion of the aluminum by oxidation.

Figure 1.  Adding 3% aluminum nanoparticles by volume increased the volumetric enthalpy of combustion by 0.9% compared with the baseline fuel.

Figure 1. Adding 3% aluminum nanoparticles by volume increased the volumetric enthalpy of combustion by 0.9% compared with the baseline fuel.

Particle size analysis of the nanofuel with PECVD coated and uncoated aluminum nanoparticles dispersed in RP-2 fuel, respectively, was conducted after initial dispersion and was repeated after one month of storage before and after sonicating; ss Figure 2.  At initial dispersion, the PECVD coated nanoparticles exhibited a median particle size that was approximately 1/3rd of the uncoated counterpart.  After one month, the median particle size increased, but after sonication, reduced to the original particle size.  However, the uncoated aluminum nanoparticles were unable to be re-dispersed indicating irreversible agglomeration.

Figure 2.  Particle size analysis of the nanofuels showed that untreated nanoparticles undergo irreversible agglomeration during storage, while the PECVD coated particles can easily be dispersed.

Figure 2. Particle size analysis of the nanofuels showed that untreated nanoparticles undergo irreversible agglomeration during storage, while the PECVD coated particles can easily be dispersed.

 

If you are interested in learning more about ACT’s nanofuels with enhanced energy density, please contact ACT today.