In [1] a simulation of yearly performance of the ASD was presented. The modifications made to the model, would yield a different estimate. Below we attempt a new prediction of performance on a yearly basis, for present state ASD, even though we do not have the results from sunnier and warmer days. This estimate can be seen in Fig. 6, also showing what would be the production in a conventional open pond, with the same size.

These results show that the yearly performance of the prototype, as it is now, should be at least on the order of 2 times (evaporation enhancement factor) the performance of a
conventional salt works. The modifications discussed above should at least bring us to a performance, at least 6 times better than the conventional salt works solution, according to the result of a simulation for yearly operation of a lowered evaporation channel ASD (0.3 m channel height).

4. Conclusions

Preliminary performance measurements of our ASD prototype showed that there is no sufficient air flow at the brine/air boundary, hindering the results. Two major modifications of the design were identified and proposed, and will be implemented as soon as possible. These are a reduction of the height of the evaporation channel and the adoption of CPC type non-imaging optics for full illumination of the solar chimney, increasing airflow velocities over the brine surface, with consequent improved convection conditions, and increase of the airflow driving force.

It was shown that a description of ASD operation can be well modelled by introducing in it internal airflow dynamics into the numerical model, namely after a more suitable calculation of head loss and airflow velocity profile around the interface region brine/air. Monitoring is on allowing for assessment of ASD operation under spring and summer conditions, permitting an even better tuning of head loss and velocity profile calculations over a more representative set of data.

Conclusion of ASD prototype testing will lead us to a final design for optimized (passive) brine evaporation, applicable to MED plant effluent treatment and salt production, as well as a software tool for ASD proper modelling.

These results will certainly be the staring point for the application of the concept and in other applications, such as wood or food drying or even in (direct) water distillation.