Initial Sketch and Workflow Document
As shown above, the initial design comprises primarily of only two parts: an outer cylinder (of
yet to be completely determined characteristics) and an inner Reverse Osmosis (RO)
membrane. Note that the diagram is not drawn to scale, as the system will most likely be much
wider than it is long in order to improve stability.
How it Works
The RO membrane cylinder, attached to the outer (main) lid, will be removed from the system,
leaving only the outer cylinder. Brine would then be poured into the main cylinder up to a
certain max fill point (as marked on the left side of the diagram) to account for the water
displaced as the inner cylinder is placed inside the solution and the system is sealed. The water
would then be boiled by a yet to be determined heat source. Because this occurs in a control
volume, the pressure in the outer cylinder would be directly proportional to the temperature of
the brine (Gay-Lussac’s Law) and rise until the needed pressure is produced in order to pass the
water through the RO membrane.
Heat
Outer Cylinder
Inner Cylinder
Updated Version(s)
Fig. 1. Vertical Model Sketch 2
Fig. 2. Vertical Model Final Sketch
Sketch 2
After continuous research, there were multiple limitations found within the initial sketch.
Firstly, RO membranes aren’t easily flexible, so it would be difficult to shape one into a cylinder
to fulfill its very critical requirements in the design. They also lose effectiveness in surrounding
temperatures above 50°C, which means using heat in the system would be counterproductive.
The second sketch seeks to resolve these problems. The most significant change would be the
use of a water pump, instead of a heat source, to apply pressure to the saltwater in the tank to
facilitate the reverse osmosis process. Four stand points are also included on each edge of the
tank to increase the stability of the system and grant space for the water pump to have access
to the electrical source it needs to work. Two detachable glass tanks are also used to make it
easier to replace the RO membrane sheet shown.
Final Sketch
The previous sketch also comes with its own limitations; the main one being what happens
after the saltwater goes below a certain level. The fluid won’t be in contact with the membrane
sheet anymore, making it harder for the whole filtration process to occur. The presence of
multiple holes in the glass tanks for the feeding tube and water pump wire could also
compromise the integrity of the system. This model seeks to resolve them with a variety of
changes, the most major one being the position of the saltwater and freshwater in the system.
The repositioning will allow for constant pressure to be applied on the saltwater, depending on
the length of the water pump tube. The water pump also has suction cups on its bottom that
will enable it to be attached to the lid.
Taking the weight of the glass tank, salt water and other components into account, the overall
weight of the system would be 200 to 220 lbs. This is ideal since the typical wooden coffee table
can hold up to 300 lbs.
Parts
Tool for adding saltwater to tank: Amazon.com : hygger Aquarium Gravel Cleaner, New Quick
Water Changer with Air-Pressing Button Fish Tank Sand Cleaner Kit Aquarium Siphon Vacuum
Cleaner with Water Hose Controller Clamp : Pet Supplies
Water Pump: Amazon.com : CWKJ Fountain Pump, 80GPH(4W 300L/H) Submersible Water
Pump, Durable Outdoor Fountain Water Pump with 4.9ft Tubing (ID x 1/3-Inch), 3 Nozzles for
Aquarium, Pond, Fish Tank, Water Pump Hydroponics : Pet Supplies
Glass tank(s): Amazon.com : REPTI ZOO 10 Gallon Reptile Tank Glass Natural Cages Terrarium
20" x 12" x 10" Sliding Screen Top for Reptile Hamster Hedgehog Small Animals : Pet Supplies
RO membrane sheet: Veolia Flat Sheet Membrane, SE, PA-TFC, RO, 47mm, 5/Pk - YMSESP47