Presets
Playback
Apparatus
Model checks
The science
What is modelled
Brine is pumped to the top of a wall of blackthorn brush and trickles down in about 34 seconds. Wind brings dry air that takes up water vapour, leaving the salt behind in a more concentrated brine. A finite holdup of liquid sits in the wall at any moment.
Equations
- Evaporation potential
E = k A √(u + 0.3) psat(T) (1 - RH) w, w the wetness factor. - Tetens saturation pressure
psat = 0.61078 exp(17.27 T/(T + 237.3))kPa. - Water and salt balances with a drain rate proportional to the holdup (residence time 34 s).
- Dissolved salt is capped at 26.4 % by mass; any excess is deposited as crust.
Checks run in the page
- Mass balance closes to rounding error.
- Steady outlet salinity equals inlet salt flux over (inlet - evaporation).
- Tetens pressure against steam-table values.
- Evaporation scales with (1 - RH) and √(wind + 0.3).
Honest simplifications
One well-mixed holdup, constant mass-transfer coefficient and no heat balance of the brine (it stays at air temperature). It is an educational model, not a calibrated plant model.
What to try
- Choose Hot dry windy: evaporation climbs and the outlet salinity rises towards saturation.
- Choose Strong brine, low flow and watch a white salt crust form in the sump.
- Choose Humid and still: with no wind and nearly saturated air almost nothing evaporates.