Synergistic enhancement and stabilization of thermoelectric generator (TEG) performance using finned metal foam–PCM composites

Integrating thermoelectric generators (TEGs) with phase-change materials (PCMs) reinforced by metal foams (MFs) and metal fins provides an effective strategy for passive waste heat management from common thermal sources. In this study, low-density polyethylene (LDPE) waste was utilized as PCM. A novel hybrid LDPE-based buffer was proposed, incorporating multiple longitudinal metal fins and copper MF, placed between an intermittent thermal source and the TEG's hot side. An MF–RT70HC composite was applied on the TEG's cold side, eliminating the need for active cooling. A validated numerical model based on the enthalpy-porosity and volume-averaged methods was employed to model the phase change process in MF–PCM composites. The thermal resistance of the hybrid buffer was systematically adjusted by varying the fin number (2–8), MF incorporation, fin material, and buffer length (50–65 mm) under intermittent thermal loading. Electrical performance was evaluated using several indicators, with particular emphasis on the median voltage (Vmed) and voltage standard deviation (σV). The results indicate that increasing the fin number from 2 to 6 significantly enhanced heat storage, stabilized the hot-side temperature, reduced voltage fluctuations by 29.79%, and increased Vmed by 20.94%. Furthermore, MF incorporation into the finned LDPE buffer improved heat distribution, increasing Vmed from 0.947 to 0.984 V and enhancing the temperature difference across the TEG during discharging periods with minimal impact on voltage stability. Moreover, using aluminum fins instead of copper fins achieved a better balance between heat transfer and thermal resistance, resulting in a 5.7% improvement in voltage stability. Longer buffers were found to maintain stable operation over extended periods, despite relatively low output voltage.