A Developed Design of Thermoelectric Multi-effect Air Gap Membrane Distillation for Seawater Desalination

This work represents a paradigm breakthrough in the design of compact desalination systems by offering the first direct integration of thermoelectric elements into a multi-stage air gap membrane distillation (TE-MS-AGMD) module. Herein, the novelty lies in the dual functionality of the thermoelectric element: it simultaneously serves as a heat pump for latent heat recovery and as an integrated thermal energy source, eliminating the need for separate heat exchangers to preheat feed solution and external refrigeration systems for vapor condensation. This innovative arrangement resolves the limitations of current MD practices by enabling internal heat recovery across multiple stages while maintaining a minimal footprint. A comprehensive experimental investigation evaluated the influence of key operational parameters—energy input, average operating temperature, temperature gradient, and number of distillation stages—on system performance. Results demonstrate that the three-stage TE-MS-AGMD system, with a membrane area of 96.4 cm 2 per stage and an energy input of 40 W, stabilizes at an average temperature of 64.9°C, achieving a maximum permeate water flux of 5.7 kg/m 2 h with a corresponding Specific Energy Consumption (SEC) of 0.73 kWh/kg. At optimized conditions with reduced power input of 10 W, the system reaches a minimum SEC of 0.52 kWh/kg alongside a gain output ratio (GOR) of approximately 1.3. The obtained performance metrics, combined with the system's compact and integrated design, could bestow significant potential for sustainable, decentralized seawater desalination applications, particularly in off-grid and remote locations where conventional multi-component systems are impractical. • Novel TE-MS-AGMD system integrates thermoelectric heat recovery directly • Achieved minimum SEC of 0.52 kWh/kg with three-stage configuration • GOR of 1.3 demonstrates efficient latent heat recovery across stages • Compact design eliminates external heat exchanger and refrigeration system