Numerical Modeling and Dynamic Analysis of a Wave-Powered Reverse-Osmosis System

Abstract

A wave energy converter (WEC) system has the potential to convert the wave energy resource directly into the high-pressure flow that is needed by the desalination system to pump saltwater to the reverse-osmosis membrane and provide the required pressure level to generate freshwater. In this study, a wave-to-water numerical model was developed to investigate the potential use of a wave-powered desalination system (WPDS) for water production. The model was developed by coupling a time-domain radiation-and-diffraction method-based numerical tool (WEC-Sim) for predicting the hydrodynamic performance of WECs with a solution-diffusion model that was used to simulate the reverse-osmosis (RO) process. The objective of this research is to evaluate the WPDS dynamics and the overall efficiency of the system. To evaluate the feasibility of the WPDS, the wave-to-water numerical model was applied to simulate a desalination system that used an oscillating surge WEC device to pump seawater through the system. The hydrodynamics WEC-Sim simulation results for the oscillating surge WEC device were validated against existing experimental data. The RO simulation was verified by comparing the results to those from the Dow Chemical Company’s reverse osmosis system analysis (ROSA) model, which has been widely used to design and simulate RO systems. The wave-to-water model was then used to analyze the WPDS under a range of wave conditions and for a two-WECs-coupled RO system to evaluate the influence of pressure and flow rate fluctuation on the WPDS performance. The results show that the instantaneous energy fluctuation from waves has a significant influence on the responding hydraulic pressure and flow rate, as well as the recovery ratio and, ultimately, the water-production quality. Nevertheless, it is possible to reduce the hydraulic fluctuation for different sea states while maintaining a certain level of freshwater production, and a WEC array that produces water can be a viable, near-term solution to the nation’s water supply. A discussion on the dynamic impact of hydraulic fluctuation on the WPDS performance and potential options to reduce the fluctuation and their trade-offs is also presented.

A Stochastic Simulator of a Multi-Component Distillation Tower Built as an Excel Macro

“…Usage of simulation in specific situations are presented in [7] for sustainable plant design, in [8] for gasifier pressure modeling, and in [9] for analyzing a petrochemical process wastewater plant. Additional applications include treating a desalination plant [10], optimizing the drying of phosphates [11], analyzing the benzene-toluene-xylene separation train from a sustainable point of view [12].…”

Performance of a Swro Membrane Under Variable Flow Conditions Arising from Wave Powered Desalination

“…However, Folley et al [24] developed a numerical model for an autonomous wave-powered desalination system along with a pressure exchanger and found out that the SEC of a wave powered desalination plant is close to 2 kWh/m 3 for a wide range of sea states. Yu & Jenne [25] developed a wave-to-water numerical model to analyze a reverse osmosis-based wave energy-powered desalination plant for different sea conditions. Suchithra et al [26] designed a compact wave-powered desalination system suitable for disaster relief and performed a numerical analysis of it for different sea states.…”

“…2. Typically, the feedwater operates within a pressure range of 50-60 bar, significantly surpassing the osmotic pressure of seawater, as established in prior research [25]. Nevertheless, the feed pressure can be regulated by adjusting pipe diameters or employing valve configurations.…”

Limits on the Range and Rate of Change in Power Take-Off Load in Ocean Wave Energy Conversion: A Study Using Model Predictive Control

“…It has been argued that the application of wave energy to desalination, specifically reverse osmosis (RO) desalination, can be more economical than the production of electrical power [1] and several groups have worked to evaluate and advance the technology for that purpose [2][3][4][5]. The cited advantage of applying wave energy to reverse osmosis comes with the use of a hydraulic power take-off (PTO) with filtered seawater as the working fluid and direct coupling to the RO process; the advantage is that significant power conversion losses are avoided [3,[5][6][7].…”

“…These data were originally generated for [1] using the methods given in [28]. Bench-marking performance results of this study is facilitated by literature that has considered this WEC in design studies [1,3,7] and experimental testing [29], including results assuming the same rates of occurrence for sea conditions [1].…”