Technological options for thermal distillate cooling and their limitations subject to field implementation constraints and climatic conditions

Several cities in the Kingdom of Saudi Arabia often receive very hot water (46 degrees C) from the water distribution network, which is supplied by a thermal desalination plant. In this work, an effort has been made to find suitable techno-economic solutions to cool hot distillate produced from thermal desalination before being sent to the water distribution network. The main constraints considered in the study were a cooled distillate temperature of 38 degrees C when air temperatures reach 45 degrees C and relative humidity reaches 70%. Several options, such as once-through seawater cooling, distillate flashing and condensing, and cooling towers have been evaluated. Wet cooling towers were able to reduce the temperature to 38 degrees C most of the time, with the cooled temperature exceeding 40 degrees C only 7.5% of the time. However, when seawater cooling was used, about 10% of the time the seawater temperature exceeded 35 degrees C, which limited the cooling to 3.57 degrees C only, that is cooled water temperature was only 40.43 degrees C because of the constraints on the amount of seawater that could be supplied. After giving due consideration to the climatic factors, field/plant constraints and their impact on the efficiency of the solutions proposed, cooling towers were found to be the most suitable option.