Efficient thermoelectric cooling of concentrated heat loads

An efficiency improvement of 87% is demonstrated in cooling of concentrated heat loads when using thermoelectric coolers (TECs) constructed with thermally conductive printed circuit boards (TCPCBs) as compared to traditional ceramic-based TECs. Laser diodes and infrared detectors must be actively cooled but are smaller than typical TECs. As a result, heat spreading must occur between the optical component and the semiconductor pellets near the edge of the TEC. Typically, TECs based on aluminum nitride circuit boards are chosen and in some cases an AlN plate is added between the optical component and the TEC. To address this, TECs have been developed that replace the ceramic circuit boards with laminated TCPCBs containing a thick copper backing. The copper backing improves heat spreading within the TEC. A study was conducted to quantify differences in coefficient of performance (COP, heat pumped divided by electrical power consumed) when cooling concentrated heat loads. A heat source 3 mm wide was cooled by TECs ~12 mm wide, comparing ceramic-based and TCPCB-based TECs of otherwise identical design. With a fixed hot side temperature and heat load, each TEC was powered to achieve a desired temperature at the heat source. Ceramic-based and TCPCB-based TECs exhibited COPs of 0.235 and 0.440 respectively, an 87% improvement. Further improvements are achievable: adding a thick copper plate between the heat source and the TEC resulted in a COP of ~0.59 for both TEC types.