Solar Evaporator with Dual Gradient Heating Effect for Sustained and Efficient Desalination

Area of Science:

• Materials Science
• Renewable Energy Engineering
• Environmental Science

Background:

• Solar desalination is crucial for addressing global freshwater scarcity.
• Current solar evaporators face challenges with heat supply, efficiency, and intermittent solar radiation.
• Salt resistance and long-term stability are critical for practical desalination applications.

Purpose of the Study:

• To develop a dual-gradient heating solar evaporator with enhanced efficiency and stability.
• To overcome the limitations of intermittent solar radiation in desalination processes.
• To improve the comprehensive performance of solar evaporators for practical seawater desalination.

Main Methods:

• Designed a dual-gradient heating system utilizing wettability differences (hydrophilic aerogel, hydrophobic film) and phase change materials.
• Integrated a phase-change film heating layer with a phase-change aerogel evaporation layer.
• Tested the evaporator's performance under solar illumination and in darkness, assessing evaporation rate, efficiency, and salt resistance.

Main Results:

• Achieved an evaporation rate of 6.84 kgm^-2h^-1 with 90.9% efficiency under one sun illumination (5.0 wt% salinity).
• Maintained a high evaporation rate of 2.61 kgm^-2h^-1 in darkness for 30 minutes.
• Demonstrated excellent solar energy storage, 7-day stable performance, and salt resistance, producing freshwater from seawater under weak light.

Conclusions:

• The dual-gradient heating solar evaporator offers superior performance and reliability for seawater desalination.
• The design effectively utilizes solar energy and mitigates issues related to intermittent solar radiation.
• This work presents a promising approach for efficient and sustainable freshwater generation.