Reducing electric energy consumption in linear Fresnel collector solar fields coupled to thermal desalination plants by optimal mirror defocusing.

In many parts of the world, desalination is the only viable and economic solution to the problem of fresh water shortage. The current commercial desalination technologies rely on fossil fuels and are thus associated with high greenhouse gas emissions that are a major cause of climatic changes. Solar thermal-driven multi-effect distillation with thermal vapor compression is a clean alternative to conventional desalination technologies. To comprehend this process, as well as its features and limitations, extensive modeling is required. In this work, we proposed a plant design based on a solar field with a linear Fresnel collector that supplies heat to a multi-effect distillation plant with thermal vapor compression. The solar desalination plant model is implemented in the Engineering Equation Solver (EES). The system performance is investigated and a control strategy for reducing electric pumping is proposed. Results showed that 1 m2 of the solar field produces 8.5 m3 of distillate per year. The proposed control strategy resulted in a 40% reduction in electric pumping energy. Our results highlight the versatility of the linear Fresnel collector when coupled with thermal desalination.