So if your goal is to actualy HEAT something, TEC is a good way to go?



-----Original Message-----
From: Michael Rigby-Jones [mailto:mrjones@NORTELNETWORKS.COM]
Sent: Monday, January 29, 2001 3:18 AM
To: PICLIST@MITVMA.MIT.EDU
Subject: Re: [EE]: Thermoelectric coolers...


> -----Original Message-----
> From: William Chops Westfield [SMTP:billw@CISCO.COM]
> Sent: Friday, January 26, 2001 10:52 PM
> To:   PICLIST@MITVMA.MIT.EDU
> Subject:      Re: [EE]: Thermoelectric coolers...
>
> Be aware that the semiconductor thermoelectric coolers are VERY
> inefficient.
> For every watt of heat energy (can I do that?) you absorb from the "cold"
> side of the cooler, you need to dissipate something like 10 watts from a
> heatsink/fan on the "hot" side (~10% efficient ?)  There were some
> SCATHING
> reviews of the CPU coolers marketted containing such devices (to keep your
> CPU cold, you have to heat up the rest of your computer quite a bit!), and
> the "cold drink cooler" application is pretty iffy as well.  The devices
> shine when you have to get something very cold but dissipate very little
> heat - say cooling an image sensor to reduce noisee, or getting low temps
> for far-infrared (heat) imagers.  A normal refridgerator  does MUCH, MUCH
> better for removing large amounts of heat at not-so-low temperatures
> (since
> they're heat pumps, the "efficiency" is much greater than 100%)
>
> BillW
>
Absolutely, I have tried to explain this to many people who see TEC's as a
miracle solution for their cooling problem.  My first PIC project was a PID
controler that used a TEC to wavelength stabilise a laser.  A big problem
was the huge efficiency jump when switching from heat to cool, the loop
gains had to be modified depending on direction of heat flow to obtain the
fastest and most stable response.

Mike

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