Concept for surface cooling with Peltier elements

© Fraunhofer IPM
Large-area Peltier cooler: Exploded drawing (left) and prototype including measuring technology (right)

As part of an internal project, the possibilities of thermoelectric cooling for use in air conditioning in buildings, in this case ceiling cooling, were investigated. For this purpose, a demonstrator with an edge length of 0.1 × 0.1 m² and a specific cooling capacity of 50 W/m² was constructed. Precise knowledge of the heat transfer resistances in the overall system is crucial for achieving optimum efficiency. To achieve the maximum coefficient of performance (COP), it is particularly important that the temperature on the warm side of the module is kept as constant as possible. For this purpose, a phase change material, with a phase change at approx. 25 °C, was inserted into the heat sink on the warm side. The material can be periodically thermally loaded and unloaded. During the cooling phase, the demonstrator was able to achieve a COP of over 2 at a temperature difference of 10 K.