PERFORMANCE SIMULATION OF THE HEAT ACCUMULATOR OF THE ABU-DHABI SOLAR DESALINATION PLANT

The Solar Desalination Plant in Abu Dhabi has been in operation since September 1984 and has been running continuously since then. The plant has a capacity of 120 m3/d and uses seawater as the feed to a multieffect-stack (MES) distillation unit. The thermal energy requirement of this distiller is provided by a bank of evacuated-tube, flat-plate collectors having a total collector area of 1862 m2. The plant consists also of a heat-accumulator system which allows the solar energy collected during the day to be utilized at nighttime, thus allowing the plant to run continuously 24 hours per day. The heat accumulator is of the thermally stratified type and uses distilled water as the heat-storage medium. The temperature distribution inside this heat accumulator affects significantly the performance of the MES evaporator and its water production. To be able to predict accurately how this temperature distribution varies throughout the day remains a matter of importance to the designer of such solar desalination plant. Our main aim in this paper is to develop a one-dimensional, unsteady-state heat-transfer computer model and compare the results of this model with the actual temperature measurements taken at the solar plant. The model was developed in such a way as to take into consideration the different modes of operation of the heat accumulator, namely, charging, discharging, combined charging/discharging, and free cooling. A comparison between the calculated and measured temperature distributions indicates that the accuracy of the model is reasonably good. © 1990.