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Thread: Project Help- Heat Resistant Ducted Fan?

  1. #1

    Project Help- Heat Resistant Ducted Fan?

    Hi there,

    I have a quick question. I am looking for a ducted fan that I want to use to generate electricitc. Long story short I need a fan/generator set up that can fit in a 2-4" pipe that has very hot air running through it. I was thinking a model airplane ducted fan would work perfect but I am trying to find one not made of plastic. Does anybody know of any all carbon or aluminum set ups? Has everyone ever used a fan like this as a power generator?

    I would love to know your thoughts. Feel free to e-mail me directly at steve.ransom@gmail.com


    Thanks!

  2. #2

    Re: Project Help- Heat Resistant Ducted Fan?

    Hi,
    We do have some carbon fan units here http://search.hobby-lobby.com/psearch/s ... tit=Search I don't think I've ever seen one used a generator before. Be sure to post some photos and status updates on your project here.

    Thanks,
    Jason Cole

  3. #3

    Re: Project Help- Heat Resistant Ducted Fan?

    SranSom,

    Go to Rc Lander website. They have aluminium composite edfs. You can purchase these metal edf units retail from http://www.rccastle.com. These fans are used in the Lander jets and I have a 64mm Cyclone Power Red Velocity installed in my Art-Tech Mig-15. She flys around 98mph now! The RC-Lander fan units go from 120mm to 64mm in size! From here you can email Tim Won the owner, and ask him the rpm values of his fans.

    Now the fan blade is made of carbon fiber, some smaller units (64mm) are made of composite plastics, SO YOU WILL probably want to remove the fan rotor, take it to a machine shop where they can dupe it out on a CNC mill and mill you out an aluminium alloy copy. This step is only required if the gases you are going to run through the pipe are at a temperature where the fan/rotor will melt inside the fan housing. If not, you will not need to dupe out the fan to aluminium. **Remember that high heat will cause any metal to expand, so therefore, have the CNC machinist make the diameter of the fan somewhat smaller ( 2K smaller) than the original plastic fan.

    As for using these edfs as generators, purchase a edf shell but do get the composite fan (turbine), so you can make a metal copy for the CNC guy. Attach your ac/dc generator motor with some kind of motor coupling and use a shear pin on the turbine (fan) shaft and use thrust bearings!! All Turbines, especially ones that use steam or superheated air as a power source, have a tendency to "run away" at high speeds!! This is just the nature of the dam things! SO, you also MUST! use a throttle governor ( called an" over speed trip" ), that will trip or close off the supply of hot steam or air ( by way of a gate valve), in case the fan (turbine) goes beyond a certain rpm that will cause a turbine explosion and break up the fan. The throttle governor is usually a series of springs that open up when a certian high RPM is reached that activate a shut off valve.*** You can also use a simple mechanical spinning governor with the steel balls used by Jenson Steam Engines. They also sell model parts for their model steam engines. These governors spin as the engine is running and will fly wide open if the engine "runs away" to close a steam valve to the cylinders (turbine). http://www.jensensteamengines.com

    You should email Tim Won and Ask him what is the RMP raiting of his edf fans 64mm to 120mm? From this info. you will know where to set your throttle governor to trip off the supply of hot gases to the fan unit. This is like a fuse in an electrical circuit which is designed to protect a motor.

    The owner of RC-Lander company is Tim Wan and he is a very nice guy, always willing to help. He helped me on my Alfa Mig-15 upgrade project.


    P.S. there is another metal edf fan called "The Fury Fan" made by Bob Shulman. http://www.shulmanaviation.com. or you can purchase one at http://www.ductedfans.com for a few dollars less.

    If you do not want to dupe out the rotor to metal, you can purchase a Jet Cat Turbine engine from http://www.bvmjets.com just a few moving parts will give you the workability of a turbine/generator set up. **Purchase the parts, and not the entire operational turbine!!because they are very $$$. Just get the rotors , bearings and fan housing etc. All the parts and the turbine blades are made of high temp metal. I think that a slimed down Jet Cat shell with the blades may just fit inside a 4" pipe?

    Also remember that Jensen Steam Engines are developing their own line of high temp. steam turbines. They are going to come out with a NEW turbine model power plant in 2010 called the "Model 95G", and I'm sure you can purchase a seperate replacement turbine that will turn a your AC/DC generator set with no problem. These turbines are designed for the generation of electrical power by using saturated steam but they will also work for hot Air, and I think they are small enough to fit inside a pipe somewhere between 2-4". Email them and ask what is the max temp of hot air that their turbines can with stand without a failure? You do not want to heat the air too hot that will cause a blade meltdown!
    That's why it also may be a good idea to use a temperature activated shut off /safety valve in line before the turbine, in case the air is heated too hot by your "boiler". This shut off/safery valve will function automatically to close and stop the supply of dangerous hot air to your turbine and vent off the hot air to the atmosphere to prevent back flow to your heater element or boiler.


    Frank
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