Transient modeling and performance evaluation of a solar-driven HDH desalination system with phase change material storage

Freshwater scarcity in arid and semi‑arid regions calls for compact, low‑temperature desalination systems suitable for off‑grid operation. This study numerically investigates a solar‑driven humidification–dehumidification (HDH) desalination system integrated with phase change materials (PCMs) for thermal energy storage. A transient model was developed to couple solar collection, PCM charging–discharging, and the HDH cycle under variable weather conditions. Two PCMs with different melting temperatures (PCM45 and PCM60) were examined. Results indicate that freshwater production is approximately 2.1 L/h during low‑irradiance morning hours and reaches a peak of about 3.9 L/h under maximum solar input. PCM integration increases the average daily freshwater yield by nearly 10.5% compared to the non‑PCM system by extending operation into late afternoon and evening hours. While both PCMs provide similar daily enhancement, PCM45 exhibits more stable late‑hour performance due to its higher latent heat contribution. Model predictions show good agreement with experimental data, confirming the reliability of the proposed framework for performance optimization of decentralized solar desalination systems.