Performance and cost assessment of a solar HDH desalination system integrated with thermal storage: a case study

Abstract

Solar desalination systems often have limited operating hours and their operation is significantly affected by the variation of solar radiation intensity. A model of a humidification-dehumidification (HDH) desalination system integrated with evacuated tube solar collectors and thermal storage is developed and validated against available data in the literature. Operating parameters such as the maximum temperature of water heater and the mass flow rate ratio of the HDH component are optimized. The thermal storage unit consists of separate hot and cold-water storage tanks, which allow control of the water temperature leaving the storage unit. Furthermore, performance of the system for six different geographical locations in Saudi Arabia, namely Riyadh, Jeddah, Dhahran, Qassim, Sharurah, and Tabuk, is studied. The system is evaluated for four different scenarios as follows: (i) 24-h operation; (ii) with the ideal flow rate; (iii) with the average flow rate; and (iv) with the maximum flow rate. The effect of flow rate on the number of operating hours and the rate of freshwater production is also evaluated. The maximum freshwater production is 9.346 L/h and the minimum is 3.01 L/h. For a service life of 20 years, the cost of freshwater produced varies from 0.021 to 0.034 $/L considering interest rate of 2%.