SEAVAX™ - 1/20th SCALE FEASIBILITY STUDY VACUUM PUMPS
OCEAN ENTERPRISE 1 JANUARY 2015 - FEASIBILITY STUDY
The Ocean Enterprise MK1, is a 1:20 fully functional scale model of a proposed autonomous, solar powered (small) ship that is designed to vacuum up plastic from the sea. An essential ingredient for any vacuum machine is a pump, be it air or water, a pump is the heart of the system.
The most important part of a vacuum cleaner is a powerful and reliable pump. Without a pump you'd have no way to generate a hydro-cyclone. It is like the heart of the machine. We began by looking for small jet drives, but none matched our requirements. Some boat bilge pumps were suitable, but are way to expensive at around the £300 mark. We were looking for DC units with brush-less motors and capacities above 40 liters (8.8 gallons) per minute. Thank heavens for Ebay, giving us a nice selection to experiment with. For this model, we don't have the time to purpose design a pump.
PUMPS & PUMPING
Our SeaVax development model is basically a pump that sucks in polluted water via a shredding unit, filters it using hydrocyclonic chambers to extract the solids, then directs the clean exhaust water as a jet back into the ocean. Sounds simple doesn't it? Let's hope so. All of this is to be powered by energy harvested from nature. The system that we develop from these experiments, will be the subject of an improvement patent application - hence, we will not be able to publish our full results, nor the practical secrets of making such a system work, such as certain mechanical features and the machine controls or electronics, etc.
The above pump (DC50A) is made for solar water heating systems, rated at 30,000 hours life - with a ceramic impellor. It comes with a speed control for its DC brush-less motor, and can pump 60 litres (13.2 gallons) a minute @ 24 volts and 3.8 amps = 91watts, or just a shade under a quarter horsepower for two units. Dimension are: 100×84×64mm. Weight 550g. Centrifugal pumps are not good at self-priming, and clog if you are not careful with design, necessitating an open impellor design that is less efficient. We are using two of these pumps in parallel. Amazingly, they arrived on 15-1-15, not many days after placing the order on Ebay. For the full size vessel we will be developing an in-line pump using very efficient fully marinised brush-less AC motors in the 50kW range. Coincidentally, 'DC' is also the initials of one of our heroes; Donald Campbell. We are sure he would have wholeheartedly supported our efforts to clean up ocean pollution, as would his engineering guru, Ken Norris, who one of our engineers had the privilege of knowing.
It is difficult to find spiral wound vacuum hose the right size for our vacuum tubes and pump ends. This problem was solved using silicone rubber auto hoses that come in different colors. We needed a 28mm (1 1/8th") internal diameter with reinforcing. Stainless steel worm drive hose clamps (jubilee clips) are used to give a perfect seal. Best buy these in boxed sets if the sizes are okay, otherwise it gets a bit pricey. These hoses are good enough for high performance petrol racing engines.
Pumps come in all shapes and sizes. Any pump must be matched in terms of power and flow capacity and speed control is also important. Where a robot boat is concerned, the functions that a human operator might carry out must be automated - and that means robotics or remote control.
INDUSTRIAL AUTOMATION - On-board control of our pumps and other essential equipment is provided by a mix of Arduino and Raspberry Pi micro controllers. Both Arduino and Raspberry are open-source electronics prototyping platforms based on flexible, easy-to-use hardware and software. Arduino can sense the environment by receiving input from a variety of sensors and can affect its surroundings by controlling lights, motors, and other actuators. Arduino projects can be stand-alone or they can communicate with software running on a computer (e.g. Flash, Processing, MaxMSP). Other micro computer systems that may also be suitable for such controls are the: Beagleboard, Mbed and Picaxe.
Our love affair with plastic is choking the oceans. Once people know about it, they want to stop it. But how? The next question is who? Obviously, if any of the researchers involved so far had come up with a solution, they would have sorted it years ago. We are a practical think-tank fresh to the issue and without a budget. We hope to be able to collaborate with other marine organisations that are funded for this work, or who have funds to investigate viable projects. You cannot donate to us directly on this site, but we hope to identify partner sites shortly where you can support a project much like that proposed herein, or better still, our own practical experiments. Volunteer careers.
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