# Hydrogel Fiber Evaporator with Vertical Channels Integrated with Dual Heat Supply/Insulation Model for Continuous Solar Desalination

## TL;DR

This paper introduces a new hydrogel fiber evaporator design that improves solar desalination by enhancing water transport and energy efficiency.

## Contribution

The novel dual heat supply/insulation model and vertical hydrogel fiber structure enable efficient and continuous solar desalination.

## Key findings

- The HFCA strategy creates vertical water transport channels with multiscale pores, improving siphon effect and water transport.
- The dual heat model increases evaporation rates to 8.09 kg m−2 h−1 and achieves 64.74 kg m−2 outdoor evaporation over 9 hours.
- The evaporator shows superior salt tolerance, anti-oil fouling, and self-cleaning abilities.

## Abstract

A versatile yet scalable “wet-spinning hydrogel fibers assisted with constrained alignment (HFCA)” strategy is proposed to achieve a highly vertical hydrogel fiber aggregate with multiscale pore structure.The dual “heat supply/insulation model” transforms the conventional single cold evaporation into cold/hot evaporation on the side surface for the first time, maximizing energy utilization of 3D evaporator.HFCA makes a breakthrough in verticalization of water transport channels and maximum utilization of energy, accompanied with superior salt tolerance, anti-oil fouling and self-cleaning ability.

A versatile yet scalable “wet-spinning hydrogel fibers assisted with constrained alignment (HFCA)” strategy is proposed to achieve a highly vertical hydrogel fiber aggregate with multiscale pore structure.

The dual “heat supply/insulation model” transforms the conventional single cold evaporation into cold/hot evaporation on the side surface for the first time, maximizing energy utilization of 3D evaporator.

HFCA makes a breakthrough in verticalization of water transport channels and maximum utilization of energy, accompanied with superior salt tolerance, anti-oil fouling and self-cleaning ability.

The online version contains supplementary material available at 10.1007/s40820-026-02120-z.

Hydrogel-based evaporators offer unique advantages for seawater desalination, yet the high verticalization of water transport channels remains significantly constrained by the random arrangement of polymers. Herein, a versatile and scalable “wet-spinning hydrogel fibers assisted with constrained alignment (HFCA)” strategy is proposed to fabricate hierarchically porous hydrogel fiber evaporator, achieving the perfectly vertical, large-scale spaces between adjacent fibers and small-scale pores within the hydrogel itself. The synergistic role of multiscale pores significantly enhances the siphon effect between fibers and the water transport capacity, while improving thermal localization, light absorption, and salt flux. Moreover, rather than employing the popular “heat isolation model”, a dual “heat supply/insulation model” is introduced for the first time in a three-dimensional evaporator, where a novel heating layer providing additional heat to the bulk water, along with an insulation layer minimizing heat loss. Together, these components create a positive net energy balance, transforming the single cold into a combined cold/hot evaporation manner on the side surface. Using this model, the HFCA evaporator exhibits the high evaporation rate (8.09 kg m−2 h−1, 1 KW m−2) among the reported hydrogel-based evaporators and achieves exceptional outdoor evaporation (64.74 kg m−2 for 9 h), accompanied with salt tolerance, anti-oil fouling, and self-cleaning capacities.

The online version contains supplementary material available at 10.1007/s40820-026-02120-z.