Three years ago, engineers from the USA and South Korea developed a prototype device capable of becoming a convenient source of water in remote and arid regions with no electricity. Now they have doubled the system’s performance and replaced expensive materials with more affordable ones. The device produces about 0.8 liters of water per square meter of surface area per day and is fully autonomous.
The device, invented by MIT specialists together with their colleagues from other countries, works on the difference of day and night temperatures. Absorbing material extracts moisture from the air and collects it as a liquid on the surface. However, the device required special materials – metal-organic frame structures (MOF) – that were expensive and difficult to access, so the economic use of the invention was not justified.
In order to correct this, scientists developed a new version of the device. It features the second stage of desorption and condensation, as well as the use of other absorbent material. The performance of the system and the possibility of mass production has increased significantly, writes MIT News.
Instead of MOF, the material used is zeolite, which, in this case, consists of microporous iron aluminum phosphate. This is a widely available, stable material with sufficient absorbent properties. The sun, heating the top plate, transmits heat to the zeolite, which emits moisture collected overnight. The moisture condenses on the copper plate, which connects to the second layer of zeolite and also serves to remove heat. Drops of water from both layers are collected in a container.
In terms of performance, the system is twice as efficient. The exact figures depend on air temperature, time of year and humidity, but are approximately 0.8 liters of water per square meter per day.
Further customization and selection of materials will further improve efficiency, the developers believe. In addition, the system operates at a humidity of only 20% and does not require any other energy than solar. That is, the system can be fully autonomous.