Dynamic modeling and analysis of a direct contact membrane distillation system with heat recovery

Direct contact membrane distillation (DCMD) driven by low-grade heat sources respresents a sustainable solution to exisitng water scarcity challenges. However, current studies primarily focus on steady-state analyses on isolated modules, limiting the understanding of dynamic behaviors for multi-component coupled systems. The present work investigates the transient performance of a solar-powered DCMD system with heat recovery (HR). A dynamic model is established and validated with experimental data. Subsequent system analyses reveal that membrane module scale significantly influences dynamic responses under various thermal perturbations. When subjected to a 20 % stepwise heat source temperature disturbance, the response time escalates by 140.8 % as the membrane length increases from 2 m to 10 m. A longer membrane module also demonstrates remarkable capability in attenuating periodic temperature fluctuations originating from intermittent solar input. Additionally, the improved thermal storage capacity mitigates the dynamic fluctuations of the system when powered by solar energy, thus prolonging high-performance operation and reducing specific energy consumption by 4.4–13.2 %. The characteristic response time of DCMD system (100–200 s) proves to be an order of magnitude shorter than conventional desalination technologies, establishing its unique advantage in rapid-response solar applications. These findings offer valuable guidance for engineering applications and the development of control strategies for solar-powered DCMD-HR system.