Efficient passive solar desalination using cooling tower integration and thermal insulation

Area of Science:

• Environmental Engineering
• Renewable Energy Systems
• Water Treatment Technologies

Background:

• Freshwater scarcity is a critical global challenge, especially in arid regions with limited infrastructure.
• Conventional desalination methods often rely on fossil fuels or external electricity, increasing costs and environmental impact.

Purpose of the Study:

• To design and evaluate a passive, solar-powered desalination system for continuous freshwater production.
• To enhance water recovery efficiency during both day and night cycles.
• To assess the system's environmental footprint and economic viability for decentralized water generation.

Main Methods:

• Integration of a solar water heater, thermally insulated evaporation chamber, and spiral condenser coil with a water-based cooling tower.
• Field testing in Tehran, Iran, during August and September 2023 to measure daily water output.
• Analysis of water quality, embodied carbon footprint, and economic performance (cost, IRR).

Main Results:

• The integrated cooling tower increased daily water output by 231-287% (p < 0.0001).
• Overnight production yielded approximately 1936 mL of distilled water due to effective thermal insulation.
• The system demonstrated zero operational emissions, a low embodied carbon footprint (0.139 kg CO2/L), and a favorable 5-year cost of 0.105 USD/L with a 26.50% IRR.

Conclusions:

• The passive solar desalination system with a cooling tower and thermal insulation significantly enhances water yield and operational efficiency.
• The system provides a scalable, sustainable, and cost-effective solution for decentralized freshwater generation in off-grid, water-stressed regions.
• This innovation outperforms conventional passive desalination systems in distillate output and energy conservation.