A thermoelectric cooler (TEC) project has been inherited. A sanity check on some basic thoughts would be welcome.
The collection of parts previously purchased (ebay or Amazon) include thermoelectrics ranging from TEC1-12703 to TEC1-12712. While not from this manufacturer, there is basic information at
formatting link
The exterior dimensions are all the same.
Each part number has 127 couples. I assume that the cross sectional area of the two posts that make up a couple goes up with the current rating. This goes along with the decreasing resistance shown in the far right column.
The second assumption is that the thermal conductivity from plate to plate on the module goes up with the current rating, due to the increased area of the posts. This conductivity is an undesired load that is increased by using an oversized TEC.
thermoelectrics ranging from TEC1-12703 to TEC1-12712. While not from this manufacturer, there is basic information at
of the two posts that make up a couple goes up with the current rating. T his goes along with the decreasing resistance shown in the far right column .
e on the module goes up with the current rating, due to the increased area of the posts. This conductivity is an undesired load that is increased by using an oversized TEC.
They cost more, there's a lower thermal resistance from the part whose temp erature is being stabilised to ambient (as you have mentioned) and you tend to need a bi9gger, dearer, lower thermal-resistance-to-ambient heat sink o n the exhaust side of the Peltier junction, and a more powerful drive for t he bigger Peltier junction.
All perfectly obvious. Why did you need to ask?
Sloman A.W., Buggs P., Molloy J., and Stewart D. "A microcontroller-based d river to stabilise the temperature of an optical stage to 1mK in the range
4C to 38C, using a Peltier heat pump and a thermistor sensor" Measurement S cience and Technology, 7 1653-64 (1996)
has an appendix A on calculating what your Peltier junction and it's exhaus t heat sink does for you.
Linear Technology's AN-89
formatting link
should have provided the same information, but when I asked Jim Williams wh y it didn't he gave me the Stephen Hawking defence - "each equation in the text halves the number of readers" which probably isn't true for applicatio n notes.
E-mail me (at snipped-for-privacy@ieee.org) if you want a reprint of the 1996 paper
ea of the two posts that make up a couple goes up with the current rating. This goes along with the decreasing resistance shown in the far right colu mn.
ate on the module goes up with the current rating, due to the increased are a of the posts. This conductivity is an undesired load that is increased b y using an oversized TEC.
mperature is being stabilised to ambient (as you have mentioned) and you te nd to need a bi9gger, dearer, lower thermal-resistance-to-ambient heat sink on the exhaust side of the Peltier junction, and a more powerful drive for the bigger Peltier junction.
I often feel like I'm beating a broken drum, but the other reason is too bi g a TEC implies too small a heat sink! and that can lead to thermal runaway . I don't think you can make too big a heat sink.
George H.
driver to stabilise the temperature of an optical stage to 1mK in the rang e 4C to 38C, using a Peltier heat pump and a thermistor sensor" Measurement Science and Technology, 7 1653-64 (1996)
ust heat sink does for you.
why it didn't he gave me the Stephen Hawking defence - "each equation in th e text halves the number of readers" which probably isn't true for applicat ion notes.
Plus you're more vulnerable to the TEC pillars cracking due to CTE mismatch.
On the other hand, sometimes the increase in mechanical shear strength and shock resistance is worth it.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics
160 North State Road #203
Briarcliff Manor NY 10510
hobbs at electrooptical dot net
http://electrooptical.net
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.