Heating/Cooling Peltier Devices 1

[shawnee]

Hi, I have two small metal pipes about half the diameter of a pencil and each are about 200mm long. I would like to be able to keep one pipe at 70 deg C and one pipe and 20 deg C. Can anyone recommend any devices or methods to accomplish this. I'm aware that heat tape could be used for the hot pipe but how can I maintain the cooler one at 20 C. Also does anyone know I might use thermal electric/peltier devices here? Thanks!

 

[MikeHalloran]

The problem with maintaining 20C in a 20C-ish ambient (you didn't say) is that sometimes you have to heat, and sometimes you have to cool.

If you can tolerate a workable deadband (you didn't say), you could use a Peltier cell to heat or cool the 20C pipe, and just change the polarity you feed it. Peltier cells require a fair amount of current, so the switch or H-bridge you need is not trivial.

If you need a very small deadband, it may be easiest to put a cooler and a heater in series thermally. A Peltier cell is probably the simplest cooler you could use, but it may not be the cheapest; I have seen it done with small vapor compression refrigeration units. You could use a resistive heater or another Peltier cell for heating.



Mike Halloran
Pembroke Pines, FL, USA