Exploring Direct Parabolic Trough Supercritical Brayton Cycle with Direct Contact Membrane Distillation (DCMD) for co-generation of Power and Water

The quest for energy sustainability and clean water is at the forefront of humanity’s challenge today. This research aims to utilize an integration of parabolic trough solar power plant with sCO₂ Brayton cycle coupled with a direct contact desalination system. An integrated model was developed to achieve the aim. The results illustrated that thermal and exergetic efficiency increased with Pressure Ratio (PR) increment and peaked at around PR of 3.2 and decreased thereafter. The change in net work output (ΔWnet), transitioning from 101 kW to 7 kW as PR increases from 2.7 to 3.2, indicates a reducing rate of increment. However, from PR 3.2 to 3.7, ΔW_net showed negative values, from -1 kW to -74 kW, reflecting not only reducing efficiencies, but also an increasing rate of its reduction. Increasing the bottoming cycle pressure continuously reduces efficiency, with minor declines between pressures of 7400 to 7600 kPa due to sCO₂ density changes near the critical point. Furthermore, the interplay between pressure ratio (PR) and the bottoming cycle (P1) affects both water production and the number of DCMD units required. Water production and DCMD units required showed an inverse relationship with sCO₂’s cycle efficiencies.