Abbreviated Report on Testing of Thermoelectric Coolers

Work Accomplished:

1. Definition of Operating Limits -

The Following conditions of service have been established as the target performance levels to be achieved by the thermoelectric cooler (TEC).

2. Suppliers of Thermoelectric Coolers and Associated Equipment -

• Two companies have been identified as sources for high temperature thermoelectrics. Both Melcor Corp., of Trenton N.J. and ITI Ferrotec of Boston Mass., offer TEC's capable of continuous operation up to 200 °C. (Marlow Industries of Dallas Tx., the only other known commercial supplier of TEC's in the U.S., and which is also the largest of the three, does not offer TEC's with operating capabilities above 135 °C.
• (3) single stage TEC's, along with a finned heat sink, cold plate, and insulating gasket have been ordered from Melcor.
• The ITI modules are currently being reviewed at this time for possible inclusion in the testing.

3. Sizing of Thermoelectric Coolers -

At present only single stage high temperature TEC's are available from Melcor. Multistage TEC's (also known as Cascades) are only offered in modules capable of operating at 150°C or lower. Since multiple stages are needed to attain the stated performance goals, single stage TEC's were selected, which will be operated in series, and should closely approximate the performance of a true cascaded TEC.

The units ordered to date were selected using Melcor's Universal Performance Graph which gives the normalized relationships between the maximum rated values of current, voltage, heat capacity and temperature differential, for a typical TEC module. By specifying a differential operating temperature or heat load to be obtained, and choosing a desired operating current, the thermoelectric's performance can be estimated, as described to the right of the graph. To select a multistage TEC, an iterative procedure was used in which the operating temperature between stages is estimated, performance of each stage is then calculated separately, and the resulting operating current compared between stages. If the current in all stages was not approximately equal, the assumed interstage operating temperatures were adjusted and the calculations repeated until a consistant operating current was obtained.

Click here to view full report (Available to CALCE MEMBERS ONLY)