Thermoelectric cooling reaches for the sky
A well-designed thermoelectric cooler drives heat from a cold surface to a hot one, maintaining an electronic device below its safe temperature. Over the past years, pulse-width-modulation (PWM) control of the supplying current has been used to improve the performance of these systems. In the EU-funded project THERMICOOL (Thermoelectric cooling using innovative multistage active control modules), researchers worked on increasing the maturity of the technology for aeronautical applications. Their aim was to move thermal management to technology readiness level (TRL) 5. First, they examined materials and cooling concepts as well as commercial systems. The use of bismuth antimony telluride (BiSbTe) was the most appropriate for enhancing thermoelectric cooling performance, while keeping the cold side temperature between 90 and 95 oC and the hot side up to 160 oC. The THERMICOOL team then developed a computational model for a BiSbTe-based module that was analysed in different thermal flow scenarios. The electronic equipment with dimensions similar to commercial systems was composed of a power core and electronics boards for monitoring and control. Lastly, they carried out an extended series of evaluation tests in the laboratory. The experimental setup comprised a thermal closet, an air heating system, power supplies, detectors collecting heat flux and temperature measurements and a control panel for monitoring the operational set-up. The experimental setup also offered active PWM control. Specifically, a DC-to-DC converter generated current pulses of appropriate patterns to supply the thermoelectric cooling module. Different power supply switching schemes were implemented for this purpose. THERMICOOL experiments showed that control loops are essential for ensuring multi-stage thermal management under harsh aeronautical conditions. Moreover, thermoelectric cooling has to be active even under moderate temperature conditions. Otherwise, cooling will be restricted in case of a fast temperature rise. Although experimental results were generally in agreement with the simulation predictions, there were also notable differences. These deviations were justified by the experimental nature of the project, and consequently, some system features were not reproduced through simulations. The first important steps towards multi-stage thermoelectric cooling have been made, calling for further research and development to meet the aerospace industry requirements.
Keywords
Thermoelectric cooling, pulse width modulation, THERMICOOL, technology readiness level, aerospace industry
