Condensation is critical for a wide range of applications such as electrical power generation,distillation,natural gas processing,dehumidification and water harvest,and thermal management.Compared with‘‘filmwise&quo...Condensation is critical for a wide range of applications such as electrical power generation,distillation,natural gas processing,dehumidification and water harvest,and thermal management.Compared with‘‘filmwise"mode of condensation(FWC)prevailing in industrial-scale systems,dropwise condensation(DWC)can provide an order of magnitude higher heat transfer rate owing to drastically reduced thermal resistance from the formation of discrete and mobile droplets.In the past,promoting DWC by controlling surface wetting has attracted wide attention,but DWC highly relies on non-wetting surfaces and only lasts days under practical conditions due to the poor reliability of coatings.Here,we developed nanostructured graphene coatings on nickel(Ni)substrates that we can control and enhance the nucleation of water droplets on graphene grain boundaries.Surprisingly,this enables DWC even under normal‘‘wetting"conditions.This is contradictory to the widely accepted DWC mechanism.Moreover,the Nigraphene surface enables exceptional long-term condensation from days to more than 3 years under practical or even more aggressive testing environments.展开更多
Moisture removal and water recovery from the air are vital for regulating indoor humidity and mitigating water scarcity.Most atmospheric water harvesters(AWH)focus primarily on increasing the moisture capture rate,but...Moisture removal and water recovery from the air are vital for regulating indoor humidity and mitigating water scarcity.Most atmospheric water harvesters(AWH)focus primarily on increasing the moisture capture rate,but for it to be economical and sustainable,it is essential to consider the energy required to recover and harvest the captured water.Here,a mechanically flexible,biphilic sorption-based AWH made of green,environmentally friendly material is presented.It consists of a hygroscopic chitosan polymer embedded within a flexible,hydrophobic silica xerogel that can harvest 86.3 g water/g chitosan at 97%relative humidity and 25℃reaching saturation after 30 days(i.e.2.88 g water/g chitosan/day).Roughly 88%of the sorbed moisture was recovered by mechanical squeezing(ca.0.020 MPa)within 150 s.Repeated water harvesting experiments and uniaxial compression tests demonstrate that chitosan-silica xerogel is durable for longterm operations,providing a fast,reliable,and sustainable moisture removal and water harvesting tool.展开更多
基金supported by the National Science Foundation(NSF)Program of thermal transport processes under Grant No.1336443。
文摘Condensation is critical for a wide range of applications such as electrical power generation,distillation,natural gas processing,dehumidification and water harvest,and thermal management.Compared with‘‘filmwise"mode of condensation(FWC)prevailing in industrial-scale systems,dropwise condensation(DWC)can provide an order of magnitude higher heat transfer rate owing to drastically reduced thermal resistance from the formation of discrete and mobile droplets.In the past,promoting DWC by controlling surface wetting has attracted wide attention,but DWC highly relies on non-wetting surfaces and only lasts days under practical conditions due to the poor reliability of coatings.Here,we developed nanostructured graphene coatings on nickel(Ni)substrates that we can control and enhance the nucleation of water droplets on graphene grain boundaries.Surprisingly,this enables DWC even under normal‘‘wetting"conditions.This is contradictory to the widely accepted DWC mechanism.Moreover,the Nigraphene surface enables exceptional long-term condensation from days to more than 3 years under practical or even more aggressive testing environments.
基金Innovation and Technology Commission,Grant/Award Number:ITS/022/15Research Grants Council,University Grants Committee,Grant/Award Number:E-HKUST601/17+2 种基金The European Union-Hong Kong Research and Innovation Cooperation Co-funding Mechanism,Grant/Award Number:E-HKUST601/17The European Union's Horizon 2020,Grant/Award Number:BIORIMAthe Project of Hetao Shenzhen-Hong Kong Science and Technology Innovation Cooperation Zone,Grant/Award Number:HZQB-KCZYB-2020083。
文摘Moisture removal and water recovery from the air are vital for regulating indoor humidity and mitigating water scarcity.Most atmospheric water harvesters(AWH)focus primarily on increasing the moisture capture rate,but for it to be economical and sustainable,it is essential to consider the energy required to recover and harvest the captured water.Here,a mechanically flexible,biphilic sorption-based AWH made of green,environmentally friendly material is presented.It consists of a hygroscopic chitosan polymer embedded within a flexible,hydrophobic silica xerogel that can harvest 86.3 g water/g chitosan at 97%relative humidity and 25℃reaching saturation after 30 days(i.e.2.88 g water/g chitosan/day).Roughly 88%of the sorbed moisture was recovered by mechanical squeezing(ca.0.020 MPa)within 150 s.Repeated water harvesting experiments and uniaxial compression tests demonstrate that chitosan-silica xerogel is durable for longterm operations,providing a fast,reliable,and sustainable moisture removal and water harvesting tool.
