Thermal Management of Electronics under Cyclic Heat Loads Using Graphite-Assisted Heat Sink

The primary objective of this experimental study is to establish a methodology for enhancing the operational duration and concurrently reducing thermal fluctuations within cyclically functioning electronic devices. In instances where electronic devices operate with intermittent duty cycles, they are susceptible to temperature fluctuations. This, in turn, can induce thermal fatigue, ultimately posing a risk of malfunction. This study introduces a novel square-shaped heat sink design integrated with phase change material (PCM) and enhanced by vertical fins. The experimental evaluation involves subjecting this design to various heat loads characterized by sinusoidal, triangular, sawtooth, and square profiles. Initially, when different constant heat load values were employed, surprisingly, despite its lower melting point temperature, Eicosane consistently outperformed Docosane by a remarkable 37% in terms of heat sink performance in enhancing operating time. However, when cyclic heat loads with intermittently varying profiles were introduced, Docosane demonstrated superior performance. To extend the operational time and improve thermal management, expanded graphite was introduced as a thermal conductivity enhancer into PCMs at various mass fractions. Four distinct PCM mixtures were prepared, each with different expanded graphite (EG) proportions, namely: 70% PCM-30% EG, 75% PCM-25% EG, 80% PCM-20% EG, and 90% PCM-10% EG. These mixtures were rigorously tested under the cyclic heat loads defined in the study.