Biogenic seashell-filled epoxy composite as perimeter insulation for a thermoelectric cooler

This study evaluates an epoxy composite containing 13 wt% biogenic seashell powder as perimeter insulation for a thermoelectric cooling (TEC) module (TEC1-12706), in comparison with a rubber–cotton foam and with no insulation. Each configuration was tested five times for 60 min under forced convection (2.5 m/s; ambient temperature 25 ± 1 °C). At 60 min, the cold-side heat sink with the shell–epoxy layer reached 12.4 ± 0.5°C, against 17.2 ± 0.4°C with foam and 18.3 ± 0.5°C without insulation, and the sink-to-sink temperature difference was the largest of the three (24.1°C, against 18.8°C and 22.8 °C). The colder sink, however, did not cool the air: the cold-side air temperature fell by only 1.3°C with the composite, against 2.0°C with foam and 3.7°C without insulation. The supply voltage also sagged further in the composite runs (10.0 V, against 11.3 V and 11.5 V), and the model-derived coefficient of performance (COP) at 60 min was consequently higher for the composite (0.858, against 0.797 and 0.755). When the three configurations were evaluated at a common supply voltage using their measured temperatures, however, the composite gave the lowest cooling capacity and COP at every time point after the start. The lower cold-sink temperature is therefore consistent with reduced heat exchange between the sink and the airstream rather than with better insulation, and no efficiency benefit was demonstrated in this arrangement. The requirements for a fair experimental comparison of TEC insulation materials are identified.