Enhancement of boiling generally follows single phase convective augmentation added to which bubbles generated tend to be divided by the wire into smaller bubbles increasing their surface area and benefiting from their turbulent mixing behaviour. Reducing wall temperature prevents the onset of nucleate boiling. Exchanger area in sub-cooled region can be shortened, releasing more area for evaporation.
Where total vaporisation is required at high heat fluxes, enhancement is often applied to:
Enhancement mechanisms at the wall are similar to condensation, mixing / boundary layer interruption but with the elements reversed from that preferred in single phase use. In addition the hiTRAN elements effectively distribute fluid evenly over the whole tube surface compensating for any mal-distribution that may occur at the inlet.
Adding to the beneficial enhancement effects in boiling, hiTRAN Matrix Elements can be effectively used to de-entrain droplets formed towards the outlet of total vaporisers. The occurrence of droplets usually occurs under high heat flux / high throughput conditions.