It’s estimated by the World Health Organization that only 60% of people in the world have access to clean water. This is simply unacceptable as it means that 2 800 000 000 people don’t have access to the key to life. 2 billion, 800 million people. That’s approximately 7 times the American population. This is an area that evidently needs improving, and when given the stimulus, 'use what you have to make the world a little better' these states lead us to thinking of ways to attempt to combat this problem when tasked with our IB group 4 project.
Our first idea led us to using something that resembles a solar oven. We wanted to try to develop a way to heat water without having to use firewood or a gas stove. By heating the water to a high temperature, you'd kill any harmful bacteria, and make water that would be otherwise not drinkable, potable.
For this design to work, we'd have to wrap aluminium foil around something that is a parabolic shape. This is because a parabola has a focus point; a point where parallel rays of light will all converge, once reflected.
This was where we ran into difficulties, because it was difficult to create a perfect parabolic shape with the materials that we had. This meant that when we reflected the light rays, they did not have an exact focus point, and as such, did not raise the temperature of the water by a significant amount. Although there was a raise in temperature in the solar heater compared to just remaining outdoors, it was not signifcant enough to raise the temperature of the water to a high level. We did a comparison between water being heated by just sitting out in the sun, compared to water heated using the solar heater, and there was only a difference of a few degrees, and was certainly nowhere near hot enough to boil. This was mainly due to the shape of our parabolic mould (which didn't resemble a parabola very well), as well as aluminium foil not necessarily being the best reflective surface to use.
Another issue with this is that it does not allow for the heating of water when it's a cold or cloudy day. The solar heater would be dependent on the weather, which is not something that can be consistently relied upon. So for these two reasons, we turned our attention to another idea.
The Water Vapour Condenser
After having little success with using the solar heater we were left with the question, if we cannot cleanse dirty water, can we produce clean water? We began thinking of alternate ways to extract water from various things and eventually decided we should try to get water from the vapour in the air.
Initially our idea was to gather air and move it into a system to be cooled and allow the vapour to condense. For this to work we’d need, A) a way to move the air into the system, B) a system which was able to cool and condense the water vapour, C) an effective way to store the water we condensed, and D) a way for people to access the storage for water when it was needed.
Addressing point A)
Addressing how to gather the air (A) was quickly resolved through a short brainstorm. Our group concluded using a fan to spin in the breeze/wind to power a weak vacuum was a straightforward yet effective solution. This remained almost identical from our planning stage to the final model of our idea. Initially we thought to have a large fan at the front of the system and have the system elevated into the air. However due to how we progressed our thinking in the other sections we adapted this to be on the side of the project and have a smaller fan.
Above is a diagram of the set-up of the fan system on the outside of the pipe. The idea is that the wind blows the fan on the outside, which spins the cog on the inside, which consequently spins the other cog. Then the fan facing downwards would rotate, and push the air downwards. This would result in a small vacuum being created, which will pull more air in from the top of the pipe. The very top of the system is also able to rotate, depending on the wind direction, so that the fan will always be pulling air into the pipe with the wind, rather than against it.
Addressing point B)
With air now being moved into a closed system we needed to find a way to lower the temperature of the air that was moved inside. Initially we thought to try and use the wind turbine to power a cooler but quickly we decided that we could not replicate that without spending amounts that could afford to solve the problem more effectively. As a result we moved away from trying to use a cooler and looked for a more natural way to lower the temperature. We then decided to move the system underground where there is no exposure to sun use the naturally lower underground temperatures. We would leave the fan system above ground obviously and linked it to the underground system via a lengthy pipe.
On top of the temperature being cooler underground, as the air moves through the pipe, it narrows as it enters the water storage area. This narrowing physically condenses the air as it flows through, which also cools it further. This, combined with the coller ground temperatures should be enough to condense the water vapour contained within the air.
Addressing point C&D)
Now that we theoretically would have water condensing we’d need to find a way to store it and have easy access. We aimed to waste as little water as possible so we’d need 100% of the storage volume to be accessible at any given time. As a result we concluded that a plain box would leave water at the bottom of it and be subject to the temperature of the earth touching it. So perhaps a bag would be better solution. We decided it would be came to the same issue with water being stuck at the bottom of it. Which leads us to installing a raised, 45 degree, ramp inside the storage chamber so water would roll directly to the bottom of the ramp, where we would install a tap to give the people access to their water. However with the system being so far underground a tap would not be an easy feat without some pipe work. So the idea of a pump was raised to pull the water up and have it distributed that way and we all agreed on this.
How the Entire System Works
A crucial feature of our project is how the water vapour travels to the chamber. This is done through negative pressure. Much of the original concepts involved using electricity in order to create a vacuum, drawing water vapour into the chamber, some original ideas involved using solar power, a gasoline engine or a wind turbine. After some discussion, we agreed we would use an unconventional method in order to collect the water vapour. This method involved a wind turbine cog system.
The Fan System
This system uses wind to spin a turbine, this turbine is attached to another turbine located within the pipe, the inner turbine is attached to the outer pipe through a cog system. In a nutshell, as the outer turbine spins, it spins a cog found within the pipe, this cog is connected to another cog, as this second cog spins, it spins the turbine located within the pipe. The blowing of the air downwards creates negative pressure, allowing for water vapour to be drawn inwards, into the chamber.
A crucial problem of the negative pressure system, was the buildup of pressure within the chamber. This was remedied by having a series of small sealable and unsealable pipes leading from the chamber to outside. The pipes are sealable to ensure that the input of air to the chamber is always higher than the output of air out of the chamber.
How it Condenses
The chamber will be placed deep within the earth, this depth will ensure that the temperature is consistently 17-23 degrees celsius. This consistency of temperature will ensure that the water vapour is able to condense within the chamber. Eventually as the water condenses, it will collect within the chamber, allowing for the water to be collected, then drunk.
The chamber will be constructed so that it is at an angle, this angle will allow the condensation of the water to collect at one end of the chamber, making access the water much easier.
The water will be collected via a direct hand pump system. The system works by an individual lifting and pushing on a lever, this lever sucks water upwards into the pump by creating negative pressure, allowing the water to be collected. This would also not require electricty, and is a hand powered pump, meaning the system runs entirely independent of electricity.
Our Final Model
Below is a photo of our final model, which represents the main features of our concept. It is not working by any means, but it allows you to visualise how the system would work, if put into place.