Im looking at using a TEC in a project to help keep me comfortable when I'm on my motorbike. I want to use a TEC to either heat or cool water that will be pumped around a set of tubes attached to a set of thermal underwear, similar to what astronaughts use in spacesuits. In the summer it can get very hot when you're riding around a city in all the protective gear but in winter you can get incredibly cold when you're riding quickly. My question is this: If I reverse the polarity on the TEC will the hot side become cooled and the cold side become hot? I had thought that TECs were like diodes, with the current in the correct direction one side becomes hot and the other cold but if you reversed the polarity no current would flow and nothing would happen. I have now come accross a piece of information that suggests that reversing the polarity would just swap the hot and cold sides. I've never worked with TECs before and if someone who has could straighten this out I'd be very grateful. Thanks Moriquendi
Peltiers are not like diodes... If you reverse the polarity on them, the heating and cooling sides will switch. Quick google search pulls this up... http://www.tellurex.com/12most.html Interesting read... Never knew how the peltier worked myself until I read the article. I did know that reversing the polarity changed the heating / cooling sides though.
Thanks for the clarification, I think I must have read P-N junction and thought "hmm, diode" I shan't be boiling my vegetables, the plan is to try and keep the temperature inside all the protective clothing comfortable. When you're riding in a city or town you're generally riding slowly with lots of stops for traffic lights etc. This can be a pretty physical activity, particularly if your bike is big and heavy like mine is and you get very hot and sweaty very quickly. It's very tempting to ride without the armoured jacket & trousers but even at low speed accidents can be bad. I'm hoping that by running cool/cold water through tubes in the underwear (longjohns and long sleeve T-shirt) I'll be able to avoid getting too hot. The flipside of this problem is that when the air is cold and you're batting along the motorway and 70 odd mph it sucks heat out of you incredibly quickly no matter how much clothing you have on. Having warm water pumped through the tubes would help to keep me warm. You can buy electrically heated clothes but they're expensive and sometimes you can be too hot riding in a city and then freezing cold on the motorway all in the same ride. I'm hoping to be able to change from heating to cooling on the fly. Moriquendi
I'll post pictures of it when it's done though there's nothing revolutionary about it, astronauts have been using the same sort of thing for 50 years. Depending on the power consumption it might be possible to have the thing run off a battery pack even after you get off the bike. Moriquendi
Interesting, but pretty badly written. Such large blocks of text are pretty obstructive to learning imo, it'd be much better with a couple of flow diagrams and some bullet points once you get the PN combo going. Semiconductors are a fascinating thing really, it's amazing what you can do with a PN junction!
I was messing around with a peltier, there loads of fun. these are some thing i learned. the hot side is hot and needs to be cooled they take lots of power you can reverse polarity and it does reverse hot and cold sides if you don't use a heat sink, they burn, literally the cold side will form condensation. probably already knew this, but there really fun to mess around with
had a buddy who got all into fish tanks for some reason.. he was asking me about putting a peltier to cool the water off in the summer.. he'll spend a thousand dollars on sharks and this big tank and then wants to rig up some half ass peltier to save a few dollars XD put it through a rad like a small heater core off a car would probably work nm maybe I should actually read the whole op XD thermal underwear wtf! =] you can use those butane heaters- they fit in your pocket.. probably be fine down there.. I used to wear a good set of gloves.. guy worked with back then had a full body suit he'd hang in the dock every morning- riding bike in the winter just sucks to be honest.. gave it up for a car
Underwear doesn't just mean pants and the whole point is to be able to choose between heating and cooling. Moriquendi
stonedsurd is right, you need to keep the hot side as cool as possible. The TEC itself is pretty inefficient so some sort of beefy heatsink is required, or ideally watercooling (perhaps the first use of DangerDen on a motorbike? ). IF the heat from the hot side conducts to the cold side, you'll get bodyheat+TEC heat+hot side heat, which is a positive feedback loop with Chernobyl at the end.
I plan on using a sodding great heatsink on the hot side with a scoop to force air through it at high speed and a fan for when the bike isn't moving very fast. I would like to avoid watercooling the hot side because that would require another pump in addition to the one pumping water around the suit. Moriquendi
Wonder if it's possible to use an aircraft-wing shaped heatsink or something like that to create negative pressure at the back and help suck it through the fins
