Solar Desalination by Humidification–Dehumidification: A Review

The scarcity of drinkable water supplies is becoming a serious and troubling challenge to long-term development. This issue emphasises the urgency of implementing rapid water desalination options. However, desalination is a capital-intensive process that requires a significant amount of energy, and since it is now mostly powered by fossil fuels across the globe, it has the potential to leave a significant carbon footprint. In this light, transitioning to green energy sources for desalination is a necessity in today’s society. Humidification–dehumidification (HD) is one of the most effective desalination procedures to consider for distant places with modest fresh water demands for household and agricultural demands. This is mostly because it requires minimal operational and maintenance concerns. The current article examines the many kinds of HD desalination systems driven by solar energy sources and their key components. The current study established that the seawater HD system is viable for producing fresh water, especially for greenhouses and dispersed demand. HD is an effective technique for eluting fresh water from concentrated brines, boosting production, and minimising harmful environmental impact, benefitting ecosystems and human services. The packed bed humidifier is the most commonly used kind of humidifier in the HD water desalination system. Additionally, as compared to an indirect dehumidifier, the direct dehumidifier improves the performance of the HD desalination system. According to the findings of this research, hybrid energy systems have the greatest gain output ratio (GOR). Solar water heating significantly increases system productivity as compared to solar air heating. When combined with a heat pump, the HD delivers optimal system productivity and GOR at the lowest cost per litre. The conclusion is that, even though humidification–dehumidification is a promising method for decentralised small-scale fresh water production applications, it needs additional improvement to optimise system performance in terms of economy and gain output ratio.