3D-printed triply periodic minimal surface (TPMS) structures: Towards potential application of adsorption-based atmospheric water harvesting

This study proposed a scalable prototype of atmospheric water harvesting (AWH), which encompasses a triply periodic minimal surface (TPMS) structure and sorbent material. This is mainly targeted for boosting water productivity via ameliorating the heat transfer and intra/intercrystalline diffusivity inside the sorbent material (i.e., silica gel). In this respect, Gyroid as a TPMS structure was 3D-printed using AlSi10Mg powder, which has a superior surface area-to-volume ratio and elevated thermal conductivity. Additionally, the thermoelectric module was employed for dual periodic cooling and heating of the sorbent material, ensuring multi-cycling and continual water productivity. Three relative humidity levels (i.e., low, moderate, and high) were used to examine the daily water productivity and system efficiency for the AWH system with TPMS in comparison to pure sorbent. It was found that, under humid conditions (70 %RH), the utilization of TPMS indicated a daily water productivity and system efficiency of 136 L/kg m2 and 6.8 %, respectively. By contrast, the AWH system without TPMS exhibited a daily water productivity and system efficiency of 74 L/kg m2 and 3.7 %, respectively. Moreover, investigating the influence of the sorbent layer thickness indicated that decreasing the sorbent layer from 40 mm to 10 mm upgraded the water harvesting 1.9 times, achieving 391 L/kg m2. This is because of the lower vapor transport resistance of thinner sorbent layers. This research underscores the importance and proof-of-concept of incorporating TPMS-derived structures in sorbents to enhance the water productivity of AWH systems, thereby facilitating their transition to practical large-scale systems and increasing their feasibility for commercialization and real-world applications.