Nanoscale Heterostructured Films for Isothermal Droplet Formation
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Solution Overview
Problem
Conventional methods for condensation of undersaturated water vapor require energy-intensive cooling and do not effectively facilitate water harvesting or macroscopic droplet formation, especially in porous materials where condensed water is retained within voids and not easily accessible.
Innovation Solution
A heterostructured film composed of a bed of hydrophilic nanoparticles with interstitial spaces bridged by a solidified hydrophobic polymer, allowing capillary condensation to occur isothermally, forming macroscopic water droplets on the surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional cooling methodologies are used to achieve condensation of undersaturated water vapor, then condensation can be achieved, but energy consumption increases significantly
Solution Approach 1:
The patent changes the surface energy parameters by creating a heterostructured surface with specific chemical composition (hydrophobic components) and topographical features (nanoscale roughness). This modifies the vapor-liquid-solid interaction parameters, enabling condensation at higher temperatures without cooling by reducing the energy barrier for nucleation.
Solution Approach 2:
The patent exploits the phase transition from vapor to liquid through a specialized surface structure that promotes heterogeneous nucleation. The nanoscale heterostructured surface provides preferential nucleation sites that facilitate the vapor-liquid phase transition at higher temperatures, avoiding the need for cooling-induced condensation.
2Use of energy by moving object
If porous materials are used for capillary condensation, then water can be collected without cooling, but the condensed water is retained within voids and not easily accessible
Solution Approach 1:
The patent segments the porous structure into distinct functional zones: internal voids for capillary condensation and surface pores for water ejection. This segmentation allows the material to simultaneously retain water through capillary forces in the bulk while providing accessible ejection pathways at the surface, resolving the contradiction between water retention and accessibility.
Solution Approach 2:
The patent introduces surface pores as an intermediary structure that mediates between the internal capillary voids and the external environment. These surface pores act as ejection channels that allow condensed water to be expelled from the internal voids to the surface, making the water accessible for harvesting while maintaining the capillary condensation mechanism.
3Ease of operation
If a hydrophobic surface is used to induce dropwise condensation, then droplet mobility is enhanced, but nucleation is less favorable compared to hydrophilic surfaces
Solution Approach 1:
The patent applies local quality by creating nanoscale heterogeneity with distinct hydrophobic and hydrophilic regions on the surface. The hydrophobic components promote droplet mobility and coalescence, while the hydrophilic nanoscale features serve as preferential nucleation sites. This spatial variation in surface properties allows simultaneous optimization of both nucleation efficiency and droplet mobility.
Solution Approach 2:
The patent uses a composite surface structure combining hydrophobic materials (for droplet mobility) with hydrophilic nanoscale features (for nucleation). This composite heterostructured surface integrates the beneficial properties of both hydrophobic and hydrophilic surfaces, enabling effective nucleation while maintaining enhanced droplet mobility.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The film enables spontaneous formation of macroscopic water droplets at sub-saturating conditions without cooling, facilitating efficient water harvesting by exploiting capillary condensation and topographical/chemical heterogeneity.
Implementation Method 1
a heterostructured film configured to effect capillary condensation
Implementation Method 2
A different mechanism that induces the condensation of water takes advantage of capillarity and surface tension forces
Implementation Method 3
A different mechanism that induces the condensation of water takes advantage of capillarity and surface tension forces
Implementation Method 4
Condensation, the process by which a vapor transforms into a liquid as it loses energy
Implementation Method 5
Given its exothermic nature, conventional approaches for achieving condensation of undersaturated water vapor have necessitated the utilization of energy-intensive cooling methodologies
Data Source
AI summary
A heterostructured film configured to effect capillary condensation, the heterostructured film comprising: a bed of hydrophilic nanoparticles, the nanoparticles defining interstitial spaces therebetween; and a solidified hydrophobic polymer, the solidified hydrophobic polymer (i) bridging adjacent nanoparticles, (ii) partially filing some of the interstitial spaces between nanoparticles, or both (i) and (ii), and the heterostructured film having a porous surface that defines pores in fluid communication with at least some of the interstitial spaces. A method, comprising exposing a heterostructured film according to any aspect herein to an atmosphere under such conditions that water from the atmosphere isothermally forms droplets on the porous surface of the heterostructured film. A method, comprising: contacting a heterostructured film according to any aspect herein to an atmosphere so as to effect isothermal recovery of water from the atmosphere.