Abstract
Conventional cooling-type photovoltaic/thermal-humidification-dehumidification (PV/T-HDH) desalination systems are limited by PV overheating owing to full-spectrum solar absorption, mismatch between low-grade waste heat and HDH energy requirements, and low thermal recovery efficiency in single-stage configurations. To overcome these challenges, this study proposes a novel three-stage concentrated photovoltaic/thermal-humidification-dehumidification (CPV/T-HDH) seawater desalination system integrated with spectral beam filter (SBF) technology. The proposed system enables full-spectrum cascade utilization of solar energy through the coupling of spectral splitting and three-stage thermal energy recovery. A comprehensive modeling framework was developed by integrating optical ray tracing, thermodynamic analysis of the CPV/T subsystem, and a three-stage HDH model with closed-air and open-water circulation. The effects of key external factors (solar irradiance and tracking accuracy) and operating parameters (saline water flow rate, air flow rate, and extraction rate) were systematically investigated. In addition, the operational feasibility of the system in tropical coastal regions was assessed using hourly solar irradiance data from Sanya, China, and a two-stage flow regulation strategy was proposed to improve operational stability. Results show that the designed SBF achieves an average transmittance of 90.56% in the 380–1100 nm band and a reflectance of 97.23% in the 1100–2500 nm band. Under optimal operating conditions, the system achieves a freshwater production rate of 2.3 g/s and a gain output ratio (GOR) of 3.7. These findings demonstrate the potential of the proposed system for distributed solar-driven desalination in off-grid island communities. It should be noted that the present analysis is based on an idealized steady-state model that neglects parasitic power consumption, pressure losses, and ambient heat losses. Consequently, the reported results represent an upper-bound performance benchmark, while actual system performance under transient real-world operating conditions is expected to be lower.
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•A three-stage CPV/T-HDH system enables full-spectrum solar utilization for desalination.•A spectral beam filter achieves 90.56% transmittance and 97.23% reflectance.•The system delivers 2.3 g/s freshwater production with a GOR of 3.7.•The system achieves high freshwater production in Sanya during spring and summer.•A flow regulation strategy improves stability under varying solar irradiance.