Eddy Current/Friction Heater

[AscenXion]

Hello everybody. First let me say that I am glad to have found this site. My wife, my daughter, and I are going to be moving to the remote nothingness of southwestern Texas next year, and I am going to be utilizing many things from this site for our extreme off-grid living.

I found some posts and info about friction heaters and rotating magnetic heaters on this and a few other sites. I am building a toy car for my daughter right now. It is going to a 1/3 replica of my car, and it will have the option of being fully enclosed like a real car. I got to thinking that it'd be nice, here in Michigan, for her to be able to ride in it outside in the winter. Going on the idea that spinning things create friction, and friction is hot, I was wondering if there were any such things as friction heaters. I googled it, and found the coffee can thing, further searching brought me to this site and the magnetic heater alternative. This seems like it would be perfect for my situation. I just would like to get as DETAILED of an explanation that I can before I start to make sure.

I've read the basics of how to do it. And I'm actually quite a quick learner usually, but I just want to make absoulte sure, especially with the off off chance that the whole thing might catch fire, and that would definitely be bad. I'm thinking that I can just mount magnets on one of the wheels, put an aluminum plate near the magnets and some sort of ducting to get the hot air into the interior of the car. So, could someone, anyone, please provide AS DETAILED of an explanation on just how exactly to go about doing this (IF IT IS EVEN FEASIBLE) and how safe it will be, and any ideas on how to moderate the temperature or turn it off.

The interior space of the car will be less than 10 cubic feet, so not much heat will be required. Things like how thick the aluminum/copper plate should be, how many and how strong of magnets to use, how large should the spacing be between the magnets and the plate, how beszt to mount the magnets to the plate, will it overheat, will it even work, will it be safe, how to orient the magnets, how to move the heat into the car, and how much energy will it take from me pushing the car at about 5 mph (with my unicycle lol) with the wheels rotating at about 140rpms (I think, 12" diameter wheels).

I can't express how GREATLY I appreciate any and all help that anybody can give me. And for your help, I'll give you a picture of me riding my unicycle pushing my daughter in her mini Suzuki Samurai.

Thank you all so much,

Kai

[Countryboy]

The most common example of a friction heater that I can think of is rubbing your hands together when it is cold outside.

It takes a lot of energy to generate heat with friction.  (Try starting a fire with friction.)

If you want to heat a toy car with friction from you pushing the car, plan on you overheating before the car warms up.

I imagine your daughter will be far warmer if you put an extra sweater on her, rather than you trying to heat her (and the car) by expending your own body energy.  It's supposed to be 5 times easier to conserve energy, than it is to produce an equal amount of energy.

If you REALLY insist on heating the car with friction, I would recommend removing the wheels.  Push the wheelless car - you will gain heat from the friction of the underside of the car dragging on the ground.

[Countryboy]

On second thought, I just had another idea for heating the car.

If the car is windproof and insulated, it will retain a lot of body heat from your daughter.

Rig up the car to be a pedal car.  Mount the unicycle tire in the car, so she can pedal it and propel the car on her own.  (Or use old bicycle parts to make it a pedal car.)  The extra body heat she uses will help keep the inside of the toy car warmer.

[AscenXion]

She's 9 months old. I'd REALLY like for her to be able to pedal herself, but that isn't an option yet.

Spinning magnet eddy current heaters ARE used, albeit possibly very rarely, but they are out there, and they do work. I ASSUME that they are fairly efficient, and won't drain me too much.

The goal is not to just warm the car up. This is going to be a stroller of sorts, than I can push her in when we go for a bike ride. I figured that if I am not being taxed too much more (which would actually be fine, since on a one speed unicycle one can never actually spin fast enough to be using their full potential) than normal, then why not give it a try.

[wdyasq]

" remote nothingness of southwestern Texas " - now, just where may this be?  If "southwest' is the Rio Grande valley I doubt you will be wanting to heat the car. If it is Dalhart - you may need a snow plow.

Here, 80 miles Southwest of Dallas, I would be more worried about an enclosed peddle car overheating 9 months out of the year. This isn't exactly the same climate as the UP of Michigan.

Ron

[Countryboy]

I'm not suggesting that eddy current or friction heaters won't work.  However, they won't produce more heat energy than the energy you expend.  You will probably wear yourself out before you generate much heat from an eddy current or friction heater.

9 months old, and a mini car stroller changes things a bit.

If it were me, (and it's not) I would probably get one of those corn filled heating pads.  You zap them in a microwave for a few minutes, and they stay hot for a half hour or so.  (A lot of folks love them for heating pads for aching muscles.)

I'd zap the corn bag for a few minutes, and tuck it in her blankie.  It should give her something warm to cuddle with while you take a short bike ride.  

Do an eBay search for 'corn heating pad'.  For about $10, I imagine it's probably the cheapest option you are going to find.

[AscenXion]

Sorry for any ambiguity. My question was not aimed at heating it in Texas (Big Bend region), but here in Michigan (outside detroit, btw, nowhere near the U.P). However, winter night temperatures are definitely low enough to need a heater as well, so my point is still valid.

Also, as I previously stated, there will be an OPTION to fully enclose the car. Like the real one (my Samurai), the windshield, roof, doors, back top section, and tailgate will all be removable.

Anywho, the net is abound with information about IDEAS for creating eddy current heaters from windmills and such. But other than a thread here in 2003 (whose contributors I was hoping still used this board and might reply) and another vague one somewhere else. I can't find any actual information for the numbers. Other than trial and error, and hoping not to burn/fry my daughter in the process, I just don't know how to go about doing it.

I've seen reports that eddy current heaters approach 100% "efficient" (or whatever the correct word is that correlates to heat pumps being 400% "efficient"). Now, since I can't feel load on my unicycle unless I'm going up a VERY steep hill, since it can outspin any loading put on me. Adding a few magnets and a non-magnetic aluminum disk some UNKOWN distance away from them and having the only "friction" forces that I feel come from magnetic braking (or whatever the correct term is) seems to me like ALL it would do is actually provide some slightly wanted loading to my ride.

And, since the net is abound with ideas to make and patent these eddy current heaters, and since the discussion in 2003 on this board had some very knowledgable sounding people spouting out numbers like hundreds of degrees and heating 5 gallons of water in 5 minutes, I am led to believe that heating an enclosed VERY small space should be not only quite feasable, but quite a good idea. So, if anyone (PREFERABLY ANYONE FROM THAT THREAD IN 2003) with any real knowledge of eddy current heaters has anything to add, I would be ever so grateful.

[Rst]

Hi,

I have make some tests with magnets and a plate of aluminium of 12 inch at 1750 rpm with 2 hp motor and the plate heat at 654 F, but it is very difficult to spin it.

Troy Reed use the same, but it says that is too easy heat or not.

Sorry for my bad english!

[badmoonryzn]

Interesting! I looked it up and I have found nothing in detail either. I am wondering how one gets much heat from eddy current without expending the same amount of power or more as one would just running a heater with electricity or hydrocarbon. If you can get your hands on an old 10 inch reel to reel tape player they usually have eddy current induction drive motors on their reels.

You might be able to experiment with these and get some usable heat by hooking up the motors and loading them up, but again you still have to put energy in to get heat out and while it could be fun to tinker with this technology there are many other efficient ways to get a little heat that would warm up a ten cubic foot area. Just running a small generator into a load would generate some heat. Try using an RC car motor and use it as a generator hooked to one or two of the wheels. You could run a small wound wire heating element in different lengths. There are several types of wire used for heating elements you will have to just try some and make sure you start out with a high resistance so you don't burn up the motor/generator or burn the brushes.

You could use small light gage metal tubes to put the heating element in with the generator small fan to blow the heat into the car cab in the middle tube and build outer tubes like a triple wall insulated wood stove wall through to make sure no heat would get to the edge, LOL providing there is enough heat to get it that hot, but we will be positive. :-)  I hope I have given you some ideas. If you build something like this you can test it out by hooking it to your one wheeler and see if you can pull it without skidding the tire the genny attached too LOL!

You will be surprised just how much power it takes to turn a little generator like that under a load. I doubt an EDDY current induction type heater would need less power, it would be more likely to need much more. I do not have the efficiency of an application like that, but I do know Eddy current motors were used because they could be run forward and rotated backwards to keep tension on the opposite reel without overheating. Most electric motors would need to be run at their rated rpm so they would cool properly. I was always fascinated by the Eddy current phenomenon and the motors using that technology. They were also used to rewind the spools or reels and they created quite a bit of torque for their size.

I hope I have given you some ideas, just have fun doing it and enjoy that wonderful little girl. I have enjoys three of them little gems and three of the other genders. The girls are just the most precious things in the world when they are little, but at times when they reach thirteen or fourteen you want to lock them up in their room and not let them out until they are about eighteen because you might end up in jail for murdering some wiseass, undeserving boy. LOL The boys are more fun their teenage years because you can show them boy stuff like baseball, football, hockey, chasing girls with honour and watch them grin from ear to ear. I figure my life was for my kids and it gets lonely when they grow up and leave, so do all you can with them and enjoy they grow up way too fast! J

Badmoon

[badmoonryzn]

I hate to say this but you would get as much heat from a 12v light bulb in the pipe and it would be cheap and built. Get several bulbs like 3 candle power, 5, 8, 10 whatever and see how much heat you can get from them. good luck!

Badmoon

Good artists copy, Great artists steal!

[badmoonryzn]

I finally found where I saw this on this site about eddy current heaters

http://www.fieldlines.com/story/2006/11/7/212552/075

good luck

badmoon

[alancorey]

I would think it would be more efficient to skip electricity altogether and convert mechanical energy directly to heat by friction.  Something like a brake drum and shoes that you can adjust tension on from where you're pushing from, maybe with a mechanically driven fan blade for circulating the warm air inside the car.  If you're going downhill you can turn up the tension, if you're going uphill or getting tired you can reduce it.  Doesn't sound like a lot of fun to push, but I'm not very athletic.

  Alan