Showing papers by "Heather D. Willauer published in 2012"
TL;DR: In this article, a computational, multi-phase model was developed to study the interactions between water droplets and radial expansion of a gas cloud in a spherical chamber, and the Navier-Stokes solutions showed that the child droplets accumulate near the shock front and evaporate at a 100 times higher rate than the parent droplets.
Abstract: A computational, multi-phase, model has been developed to study the interactions between water droplets and radial expansion of a gas cloud in a spherical chamber. Initial conditions for the gas cloud are specified based on chemical equilibrium calculations for the detonation of a high explosive (RDX). Mono-dispersed water droplets are injected at uniform concentration into the chamber prior to the expansion. A Lagrangian model is used to track the breakup of the parent drops near the shock front to form child drops, which are extremely small. The Navier–Stokes solutions show that the child droplets accumulate near the shock front and evaporate at 100 times higher rate than the parent droplets. Latent heat absorption is the dominant mechanism followed by the sensible heat absorption by the water vapor (and droplets), and momentum absorption from the high velocity gases by the child droplets. The simulations also show that the water vapor formed by the evaporation increases the gas density at the shock front. The increased density and reduced gas temperature (cooling) have opposite effects on the pressure at the shock front. This leads to only a modest suppression in the pressure. At realistic droplet concentrations (0.08 kg droplets/m3 of air), the water mist is shown to evaporate completely in a short time (2.42 ms) prior to shock reflection at the chamber wall mainly due to the breakup at the shock front. High concentrations of mist may be desirable, but are difficult to achieve in practice at the total flooding conditions.
37 citations
TL;DR: In this paper, a novel electrochemical acidification process has been developed in a successful feasibility attempt to extract large quantities of CO2 in the form of bicarbonate and carbonate from seawater for potential use as a source of carbon for hydrocarbon production at sea.
Abstract: A novel electrochemical acidification process has been developed in a successful feasibility attempt to extract large quantities of CO2 in the form of bicarbonate and carbonate from seawater for potential use as a source of carbon for hydrocarbon production at sea. This indirect approach acidifies seawater by the electrolytic production of acid. Lowering seawater pH was found to be proportional to the applied current to the cell. Spontaneous degassing and recovery of CO2 below pH 4.5 was reduced from 92% in synthetic seawater to 30% in natural seawater. The effects of increased operational time, flow rate, current, and natural seawater’s complex equilibrium buffer on process performance and CO2 recovery have been shown to be essential for further improvements in future cell design, efficiency, and scale-up.
22 citations