Performance and Economic Cost Evaluation of OT-MSF Desalination Unit Integrated with A Solar Collector for Basrah City Climate, Iraq

Abstract Solar power stands out as the prime choice among renewable energy sources for competing with fossil fuels in desalination due to its ability to utilize both heat and power for the process. This study introduces the concept of employing a parabolic trough solar collector (PTSC) to power a once-through multi-stage flash (OT-MSF) desalination unit in the climate of Basrah city, Iraq. The desalination system comprises two directly coupled sub-systems: the PTSC and the OT-MSF desalination unit. The preheated feed brine water coming from condenser was used as a heat transfer fluid (HTF) for PTSC, which gets heated from solar collector to a desired temperature referred to as the top brine temperature (TBT). Numerical simulations were conducted using EBSILON Professional 16.02 (2022) software to assess the system’s performance under seasonal variations in solar irradiance availability and varying values of TBT. The effects of solar irradiance availability, TBT, mass flowrate of feed brine water, last stage temperature on the economic cost of distillate water was studied. A major finding of the current study can be summarized as follows: The highest distillate output, observed in June, reaches 159.53 kg/sec with TWC of 1.79 $/m 3 , while the lowest, observed in January, is 83.42 kg/sec and TWC of 2.02 $/m 3 , when TBT of 112 ˚C and the last stage temperature of 40 ˚C. With a total solar collector area of 130,000 m 2 , the normalized yield of the distilled water per square meter per day ranges from 55.44 to 106 kg/m 2 /day. Increasing distillate production and decreasing total water cost (TWC) are observed when the final stage temperature is adjusted to 30°C instead of 40°C. In January, distillate output reaches 93.7 kg/sec, compared to 179 kg/sec in June. While, TWC is recorded at 1.97 $/m 3 in January and 1.76 $/m 3 in June. Also, it has been observed that with the increment of TBT from 90 °C to 112 °C, the production of distillate water rises from 112.87 kg/s to 161.32 kg/s, while maintaining a constant feed brine water flow rate of 1321.62 kg/s. These findings are very acceptable when compared with an existing literature.