First Idea and Sketch

Lab's Fog Generator Improvements : Water Level Control

My ongoing PhD thesis is about understanding fog droplets motion around obstacles and more specifically trying to use these understandings to improve fog harvester. Therefore a test bench was built in the lab that allows one to simulate real conditions and test their prototypes.

It is composed of a fog generator, a laminar air flow generator, two concentric plastic cylinders and two weighing scales. The fog created by the generator is carried away by the laminar air flow and passes around a hanging obstacle. The top weighing scale measures the mass of the fog water deposited on the obstacle while the bottom one measures the mass of the water drained and hence harvested.

The interseting datas we extract from our measurements require the value of the supplied water mass rate. However, our setup does not allow us to measure it directly therefore we estimate by measuring the water tank mass before and after our measurements.

Unfortunately the efficiency of the nebulizer that creates fog depends on the water level and the fog generation slowly diminishes the water level. Therefore the supplied water mass rate is not constant and the method we use to estimate its value is not accurate for large duration measurements.

Therefore, for my Fab Academy final project I would like to build a module that can be added to our setup that would allow one to control and maintain the water level above the nebulizers and hence make the supplied water mass rate constant.

First Sketch

Here is a sketch of my actual idea of how to do it :

Communicating Vessels

The water supplier in which the nebulizer are immersed is bubbly when working. The water level is then quite hard to measure, even for a device. I would then transform the supplier in a communicating vessel with another tank whose water surface would be quite flat and therefore whose water level would be easier to measure.

Water Level Sensor and Microcontroller

In this second tank would be immersed a water level sensor that would send its measurements to a microcontroller. The microcontroller would then compare the measurments to thresholds that activate and deactivate a pump.

Let's note that most of water level sensor works using water conductivity properties. However, we use demineralized water to avoid nebulizer damaging. Therefore we must find other ways to measure water level.

Pump

When the pump is activated by the microcontroller, it adds water in the tank at a fixed rate and the water level increases. When the water level exceeds a certain value, the microcontroller stops the pump.