Thursday, August 14, 2014

Written Report


Development of  water retrieval tower for 3rd world countries.

Marcus, Henry, Marc, Darren
School of Science and Technology, Singapore

Abstract

Water is key to our daily lives. Without water, humans cannot survive. But, there has been a massive issue of people wasting water. Singapore, as a country, already has a shortage of water. With people wasting water, it brings us closer to the risk of not having enough water for everyone. Yet,water is in the air nearly everywhere on earth, even in the most parched desert. But that doesn’t help much when you’re thirsty because most of that H20 is in its vaporized form, not its handy liquid state. So how can we harvest these water and make them usable by us human through the tower? This idea of collecting water from the air is proven to be successful and will soon be deployed to help countries with drought or unsafe water supply. But for our project, the water collected is very little, and/or can be considered as a failure to collect water.  The actual water tower can collect up to 20 liters per day but our tower can only collect about 1-10 ml per day.






1.   Introduction

1.1    Engineering Problem

Many countries in the world are unable to get clean water to survive. In fact, because of unclean water, many of the people in these countries suffer from diseases such as Arsenicosis and Cholera. Thus we decided to make this Wakar Water Tower to help these less fortunate people get a source of clean water.


1.2    Engineering Goal

To retrieve water from the air and make it usable by us human as a solution to the near shortage of water in Singapore using a water harvester.

1.3    Specific Requirements
(a) Collect clean water through condensation
  -> Nitrates are at low level
(b) Reduce Cost of retrieving water by not building a factory, which cost $400 million.
(c) Easy transportation by human means. This is lighter and thus could be carried by about 5 people.
(d) Reduce working time to build this instead which can take up to 5 years.
(e) Size not exceeding 8m by 9m and weight not more than 60 kg.
(f)

1.4        Alternative solutions


Alternative Solutions
1) The 'magic mesh' that can make water out of thin air: Researchers reveal system to harvest morning fog for drinking and farming

By changing the size of the holes and fibres, researchers say they have already improved the system by 500%

Fences made from a simple system of suspended mesh structures are placed on hilltops in areas with persistent fog and prevailing westerly winds.
When the fog arrives, the water condenses in the mesh and drip down pipes to water butts, where is can be fed directly into watering systems or used by locals as drinking water.
Variations in the mesh spacing as well as the size and the wettability of the fibers in the mesh all affect the volume of water that can be collected each day.


Design 2
Water-Collecting Wind Turbine
A new type of wind turbine harvests not only electricity from the wind, but clean water from the air, by condensing humidity from even the driest climes. a harvester powered by a 30-kilowatt solar panel and a water condenser that can connect to an existing power grid. The turbine works like a typical wind turbine, with three upwind blades spinning to generate electricity. Then in a separate process, air is sucked into the turbine's nose and sent through a cooling compressor, which extracts moisture from the air. Water droplets drip down stainless steel pipes inside the turbine shaft and are collected at the base, which houses a filtration and purification system. The system is powered by the wind turbine.





Design 3
Air Well
An air well is a structure or device that collects water by promoting the condensation of moisture from air. Designs for air wells are many and varied, but the simplest designs are completely passive, require no external energy source and have few, if any, moving parts. All air well designs incorporate a substrate with a temperature sufficiently low so that dew forms. Dew is a form of precipitation that occurs naturally when atmospheric water vapour condenses onto a substrate. It is distinct from fog, in that fog is made of droplets of water that condense around particles in the air. Condensation releases latent heat which must be dissipated in order for water collection to continue.


Best solution and reason
The design we have chose is a Vase like structure made out of Bamboo/Rattan as they are strong yet light. They will be connected in lattice framework,like a plus sign, and tied together with strong cable strings. This is to ensure the tower is able to support any weight placed on it as the force will be distributed equally throughout the tower with this crisscrossing of rattan. The inside will be lined with plastic nylon mesh that have it’s own waterproof feature, eg: waxy, that allows the condensed water to slide down to the bottom to be collected. We could also install a fan at the top opening to blow the water down. This will also cool the mesh and allow more water to condense on the tower. We can also add several LEDS to indicate the position of the tower so that nearby people can easily locate the tower or aircrafts can spot the tower from far



Reasons:
  1. Easy to build
  2. Simple design
  3. Able to provide shade and place for interaction.

2.      Methods
2.1    Equipment
Material
Quantity
Cost ($)
Bamboo/Rattan
5 x 2m
10
Nylon Mesh
1 x 2m
4
Cables ties
500
5
Wire
5 x 2m
3
Bowl
1
1.5
Duct Tape
2 Rolls
0 (Brought From Home)


2.2    Diagram


2.3    Procedures
  1. Curl the 1st Rattan into position, which is a circle shape.
  2. Repeat this for at least 3 times with the last rattan being the smallest.
  3. Take a long strip of rattan and curl it side ways such that it intersects with all three circle.
  4. Tie the junction up with the cable
  5. Repeat step 3 and 4 until the tower is secure. (It can stand now)
  6. Using another long strip of rattan, curl it in the opposite direction and repeat step 4 and 5 to form an ‘ X ‘  at the junction
  7. Make 3 separate loop with the metal wire
  8. Spread the mesh over the 3 different loop.
  9. Go through the holes of the mesh alternatively to secure the mesh
  10. Attach the mesh with the other structure by hooking them in place
  11. Leave the set up for about 12hrs. ( Place )












2.4    Risk Assessment and Management
  1. We might cut ourselves as the Rattan’s end is sharp. We should smoothen the end before we use them or tape them up.
  2. We might poke ourselves with the metal wire for the frame and thus we should bend the tip of the wire such that it is blunt.
  3. We need to be careful with the mesh as our fingers might get stuck and panicking might bruise our fingers. We should remain calm and seek for help when we get entangled with the mesh.
  4. We might get hit by the rattan springing back and thus we should always maintain a firm grip on the rattan.
















2.5    Data Analysis

Day 1: We did not collect any water probably because the water was evaporating faster than the rate of condensation.

Day 2: After adding a sheet of aluminium at the top of the tower to prevent the evaporated water from escaping, we collected 10 ml of water. We suspec ted the water that was collected was rainwater as it had rained overnight .

Day 3: This time, removed the aluminium sheet on but making a narrow opening in the mesh. We managed to collect 20ml of water but we deduced that it was rainwater as it had also rained overnight.
Day 4: We combine the aluminium sheet and the mesh together. We left it overnight again and found out that there was no water in it the next day. Thus we came to the conclusion that the water that was collected during the previous days was all rainwater.










Nylon Mesh

Polypropylene Bag
Pros
1. Ensures the air circulation within the model.

2. More flexible to ensure that the water condensed will flow down at a higher rate.

1. Traps cool air inside the bag

2. Air is poor conductor of heat thus the tower would be cooler for a longer period of time.

3.
Cons
1. Absorbs some water

2. Heats up too easily

3.  Easily damaged
1. Hard to maintain

2. Hard to stick it together

Overall Effectiveness
 6/10
8/10
Experimental Design:

Our project was based on this tower: where,










So we came up with different ways to enhance the condensation process and ended up with this:

.











But adding a fan is impossible thus we created one without a fan:
But this design was proven ineffective in collecting water as the rate of condensation is slower than the rate of evaporation. Thus we ended up with another design which we added a aluminium sheet above to allow evaporated water to condense again.


After we discovered that the structure still did not work, we replaced the nylon mesh with a polypropylene bag we got from IKEA.









3.      Results

3.1    Sampling sites
This picture shows the surrounding of our site and the ‘x’ marks the spot where we put out tower.
This is the actual site of the testing place and that the tower is currently residing inside.



3.2    Experiment 1 results

Day
Time when collecting the structure :
Water collected /ml :
1
8am
1.0
2
9am
1.0
3
11.30am
1.0





3.3    Experiment 2 results

Condition changed:
Time left in the forest /Hours:
Amount of water collected /ml
Control tower
9
0
Added a aluminum sheet
9
10  (Probably                                                                     Rainwater)
Narrow opening of mesh
9
20  (Probably                                                                     Rainwater)
Added a aluminum sheet + Narrow opening of mesh
12
0
Change material of mesh
12
0.5

3.5    Special observations
The forest that we went to was not a primary forest, it was replanted twice before it is what it is as of today.
We have also found out that Condensation will form on any object when the temperature of the object is at or below the dew point temperature of the air surrounding the object

Singapore Relative Humidity: 80% …….. 24°C

Temperature /°C
Humidity / %
Relative Dew Point / °C
27
75
22
27
45
13
16
75
11
16
45
4
2
75
-2
2
45
-9










4.      Discussion

Factors affecting condensation:

Condensation will form on any object when the temperature of the object is at or below the dew point temperature of the air surrounding the object

Singapore Relative Humidity: 80% …….. 24°C

Temperature  / °C
Humidity / %
Relative Dew Point / °C
27
75
22
27
45
13
16
75
11
16
45
4
2
75
-2
2
45
-9

Definition Of Dew Point Temperature
Dew point temperature is defined simply as the temperature at which water vapor, when cooled, will begin to condense to the liquid phase

BUT
The range of a minimum temperature of Singapore is  of 23 °C and a maximum of 32 °C.


Elements of our tower that might contributed to failure:
1) Nylon mesh too big
2) Setup too small
3) Design not ergonomically fit for water to drip.
4) Structure might be too hot > 24°C

What need to be done to ensure success:
1)Maintaining the tower’s temperature at 24°C
2) A bigger sized tower
3) Need a controlled environment that does not have fluctuated temperature and we can easily monitor the tower.



















4.1    Key findings

As you can see from both graphs, there is no water collected in any of the experiment testings and this is not due to the time it was collected from the forest. Thus we can safely eliminate that this was the cause of the failure to collecting water.




4.2    Explanation of key findings
We think that the material is the main contribution to this failure as the nylon might have already absorbed all the water that condensed on this tower. Thus there would not be any water collected in the bowl below. Next, the nylon is porous making it heat up until it is the same temperature as the environment. This means that no water will condense as there is now no cold platform to condense on.

Thus, we decided to seal up the polypropylene bag as the second trial. This would mean that cool air inside the bag will be kept cool for a longer period of time (12 hours at least). As condensation can take place anytime when the bag is cool and since the polypropylene bag  is waterproof, the water droplets will drip into the bowl below.











4.3    Evaluation of engineering goals

We are able to construct a tower that is meant to harvest water with minimal materials such as rattan and tape without using equipment such as saws. Nothing was wasted as we reused the tape and rope when we remake the tower so that it is more stable. Also, no water or any other things are needed.  The current tower is about 105cm by 300cm, which is a small area, thus there would not be any problem with us transporting it around. The method used to build this is very simple too and it will take one or two person to set it up in a few hours. And last but not least, it can collect water that is safe for consumption.















4.4    Areas for improvement

1) Maintaining the tower’s temperature at 24°C as condensation cannot take place when  the temperature is over 24°C.
2) A bigger sized tower to be able to collect more water.
3) Need a controlled environment that does not have fluctuating temperature or else it might affect some of the results.
4) We can make the prototype more stable so that it can withstand the rain.
5) We can also use better materials to get better results. (e.g. rattan with better quality.)
6) A better way of presenting the data we collected so far such that it is very clear to the readers like by using a data logger.
7) A better and simple way to describe the methods to readers.
8)Stronger and more flexible materials
9)Better way to connect the rattans.












5.      Conclusion
Elements of the actual wakar water tower and testing sites that might ensure success:

1) The nylon and polypropylene fibers
They act as a scaffold for condensation
It also act as a structure for the  of dew form to flow into a basin at the base of the structure.

2) The mean minimum during the coldest season of Africa is 6° C and the mean maximum rarely exceeds 26° C.


















5.1    Summary of findings
Factors affecting condensation:

Condensation will form on any object when the temperature of the object is at or below the dew point temperature of the air surrounding the object

Singapore Relative Humidity: 80% …….. 24°C

Temperature  (°C )
Humidity ( % )
Relative Dew Point (°C )
27
75
22
27
45
13
16
75
11
16
45
4
2
75
-2
2
45
-9



Definition Of Dew Point Temperature
Dew point temperature is defined simply as the temperature at which water vapor, when cooled, will begin to condense to the liquid phase





Elements of the actual wakar water tower and testing sites that might ensure success:

1) The nylon and polypropylene fibers
They act as a scaffold for condensation
It also act as a structure for the  of dew form to flow into a basin at the base of the structure.

2) The mean minimum during the coldest season of Africa is 6° C and the mean maximum rarely exceeds 26° C.
BUT
The range of a minimum temperature of Singapore is  of 23 °C and a maximum of 32 °C.

Elements of our tower that might contributed to failure:
1) Nylon mesh too big
2) Setup too small
3) Design not ergonomically fit for water to drip.
4) Structure might be too hot > 24°C













5.2    Practical Applications
Our prototype can be used in area or country which experiences drought or have very little excess to a water source. (e.g. Africa, Saudi Arabia, India, Kenya, Bangladesh)

India
India’s growing population is putting a strain on the country’s water resources. The country is classified as “water stressed” and a water availability of 1,000-1,700 m3/person/year. According to UNICEF, in 2008 88% of the population had access and was using improved drinking water sources.“Improved drinking water source” is an ambiguous term, ranging in meaning from fully treated and 24 hour availability to merely being piped through a city a sporadically available. This is in part due to large inefficiencies in the water infrastructure in which up to 40% of water leaks out.












Kenya
Kenya, a country of 36.6 million, struggles with a staggering population growth rate of 2.6% per year (by comparison, the US population growth rate is 0.899% and the population growth rate in India is 1.31%). This high population growth rate has pushed Kenya’s natural resources to the brink of destruction. Much of the country suffers from a severe arid climate, with only scarce few areas enjoying rain and access to water resources. Deforestation and soil degradation have made the available surface water typically highly polluted and difficult to retain. The government has been unable to afford to develop water treatment or distribution systems, leaving the vast majority of the country without access to water.

Bangladesh
Historically, water sources in Bangladesh came from surface water contaminated with bacteria. As a result of drinking infected water, infants and children suffered from acute gastrointestinal disease, causing significant burden of mortality.







5.3    Areas for further study
-Is there a better material to provide optimum condensation? This is to ensure that the best material is used and thus there will be more water collected.
-Is there a more sturdy and flexible material for the structure for the tower?
We do not know if there is any stronger and better material than rattans as the rattans are very difficult to bend and to keep it in shape.
-Is there a more secure material to use besides duct tape?
We secure the rattans together using strings and duct tape, but this is proven to be not as effective thus what other kind of adhesive can we use to hold the tower in place?
-How do we make the tower waterproof?
Some of the strings are absorbing the water collected so how can we make sure that the water droplets flows down into the bowl without any obstructions.
-What is the optimum conditions for the condensation to occur in our tower?
When we test it in the forest, there is a constant change in the environment thus how can we ensure that the environment we place our tower in is the most effective and have the best conditions present for condensation.
6.      Bibliography

Vaisala Oyj (-). Preventing Condensation. [ONLINE] Available at: Oyj, V. (n.d.). Preventing condensation. Retrieved from http://www.vaisala.com/Vaisala Documents/Application notes/PreventingCondensation.pdf. [Last Accessed 25/8/14].

- (-). Ethiopia - Climate. [ONLINE] Available at: e.g. http://www.microsoft.com. [Last Accessed 25/8/14].

Arturo Vittori & Andreas Vogler ( 2012 ). WARKAWATER . [ONLINE] Available at: e.g. http://www.microsoft.com. [Last Accessed 25/8/14].

Arturo Vittori & Andreas Vogler (2014). WarkaWater. [ONLINE] Available at: http://www.architectureandvision.com/attachments/article/492/GR_LF_PJ_073_120817_WP_01.pdf. [Last Accessed 19/7/14].

Arturo Vittori (15/2/14). Architecture and Vision collects water with potable warka tower. [ONLINE] Available at: http://www.designboom.com/design/architecture-vision-collects-potable-water-with-warka-tower-02-15-2014/. [Last Accessed 19/7/14].


Arturo Vittori (4 April, 2014). WarkaWater Tower condenses air to collect safe drinking water for Ethiopians. [ONLINE] Available at: http://www.architectureanddesign.com.au/news/warkawater-tower-condenses-air-to-collect-safe-dri. [Last Accessed 19/7/14].

Flaherty, J. (2014, March 28). A Giant Basket That Uses Condensation to Gather Drinking Water. . Retrieved July 19, 2014, from http://www.wired.com/2014/03/warka-water-africa/

Kimberley Mok (April 30, 2014). Handwoven dew collecting tower aims to ease Africa's water crisis (Video). [ONLINE] Available at: http://www.treehugger.com/sustainable-product-design/dew-collecting-warka-water-tower-ethiopia-architecture-and-vision.html. [Last Accessed 19/7/14].

Rose Webster (2014). Warka Water Invention Solves a Water Crisis by Harnessing Nature. [ONLINE] Available at: http://www.environment911.org/Warka_Water_Invention_Solves_a_Water_Crisis_by_Harnessing_Nature. [Last Accessed 19/7/14].


















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