Abstract

This study evaluates the recent investigations and economic assessments on using the solar-driven organic Rankine cycle (ORC) as a power source for membrane-based desalination systems, specifically reverse osmosis (RO) systems. Several numerical and experimental studies from the last decade on the design and performance of RO-ORC desalination systems have comprehensively been reviewed. This intensive study aims to critically review RO-ORC systems and update on the recent advancements in systems performance, design, and characteristics. It also focuses on the main challenges, limitations, improvements, and techno-economic factors affecting RO-ORC performance. Four categories were used to group the investigations: the RO desalination process, the Organic Rankine cycle (ORC), the solar ORC-powered RO desalination, and economic assessment criteria. RO-ORC performance is affected by the system design parameters, RO unit characteristics, feed water qualities, climatic conditions, and the ORC process’s working fluid. The assessment focuses on recovery ratios, water quality, system efficiency, system, and plant design and the SEC as performance evaluation measures. The literature review declared that improved membrane materials and module designs have reduced energy usage because of the continual process improvements and cost savings. These advances cut membrane costs per unit of water produced in half. In addition, many modern technology combinations have been studied and used to boost efficiency and reduce energy needs in reverse osmosis plants. Using solar-driven ORC-RO has shown promising results in places with ample solar resources or low-grade thermal energy. Many conclusions and expected remaining challenges are highlighted in the study.

The design of water structures is crucial for efficient hydraulic performance. Open irrigation canals are designed with specific inside slopes to ensure maximum stability, while the wing walls of water structures constructed across the canal are designed to maximize hydraulic performance. Therefore, ensuring compatibility between the canal inside slopes and the wing wall types used on both the upstream and downstream sides is of great importance for achieving optimum hydraulic performance. However, our literature review indicates that this necessary compatibility between the canal inside slope and the wing wall type has not been adequately researched and studied. This present study aims to numerically investigate the relationship between open canals inside slopes and wing wall types, as well as examine the impact of using different wing wall types with varying canals inside slopes on hydraulic performance efficiency. Four canal inside slope ratios (Z) (H: V = 2:1, 1.5:1, 1:1, and 0.75:1) are simulated using the HEC-RAS program, along with two types of water structure wing walls (box and broken). The HEC-RAS numerical model provides accurate and reliable estimations of the hydraulic characteristics of flowing water through the structure, and the results are verified using previous experimental measurements available in the literature. The variation (ε%) between the measured and computed results is consistent for estimating specific energy, velocity, heading (afflux), and water depths. The simulation results demonstrate that changing the canal inside slope (Z) from 0.75:1 to 2:1 results in a relative increase of approximately 27.84% in heading up and 15.06% in velocity. Additionally, the broken wing wall proves to be more effective than the box type. The study confirms that the optimal configuration for the most efficient performance of water structures involves utilizing broken-type wing walls on the upstream side, along with a 1H:1V canal inside slope. This configuration reduces the relative velocity and relative heading by approximately 12% and 20%, respectively, which is considered highly favorable.