Flash atomisation of saltwater through convergent-divergent nozzles: implications for marine cloud brightening

Abstract

The potential feasibility of Marine Cloud Brightening (MCB) is currently limited by the efficiency and practicalities of technologies to generate the required flux of correctly sized aerosol particles. We studied the aerosols formed by the spray from superheated salt water through two convergent-divergent (de Laval) nozzles between 5 nm and 50 μm dry aerosol diameter. We found that they do not produce more particles useful for MCB (30-100 nm) than currently deployed effervescent nozzles. A significant portion of the mass flow through these nozzles was contained in particles larger than 2 μm. However, the production rate from these de Laval nozzles appeared unaffected by the reduction of throat diameter despite a fourfold reduction in water flow and thus power usage.