Harnessing the cold of outer space to meet our growing water needs

Sergio working at desk

Students

2020
Engineering and Applied Sciences

Faculty

Assistant Professor Electrical and Systems Engineering

Project Summary

This summer I worked with Dr. Aaswath Raman of ESE. One of his lab's topics is radiative sky cooling and its potential uses. I focused in this area of research, particularly with how radiative sky cooling can be used for dew condensation. Dr. Raman and I found that although there is a fair amount of literature on the topic of dew condensation and dew condensation with sky cooling, there was little to no information regarding the theoretical limit of this technique. In other words, what is the best way to collect the most water from the air, and how do we do this?

Usually, dew condensation with a radiative surface is done by placing the surface, tilted at an angle, on a roof and letting water condense on it. We saw this method as inefficient, since a 2016 paper by Dr. Raman showed how one needs to minimize parasitic heat losses to make radiative cooling as efficient as possible, and this method of dew condensation was not minimizing parasitic heat losses.

With this in mind, we set about creating a concept of a device that would minimize parasitic heat losses by isolating the radiative surface on the top, and pump air from the atmosphere into a chamber below the surface. The surface and this volume of air would be in thermal contact, and this is where the condensation would occur. After a certain period of time, there would be fresh air pumped into the chamber and the process would start again. A Matlab model was developed and using real data, results were found.

Steps in the future would be to better understand the calculation of the parasitic heat transfer coefficients, since there is certainly convection inside of the chamber as the air closer to the surface cools down. Another, more ambitious task, is to improve the model from treating the surface and the air underneath it as one thermal object to separating them thermally and understanding the heat gradient that would occur as the air would get progressively colder the closer it is to the radiating surface.

This project taught me a great deal about the field I worked in and has motivated me to probe it further. When I decided I wanted to study and become an engineer it was to work on project like this which have potential to do a lot of good in the world, so I'm happy of my participation in it.