An Improved Optimization Approach for Thermoelectric Refrigeration Applied to Portable Electronic Equipment

The electronics industry has relied heavily on air cooling to dissipate waste heat. Each new generation of technology is smaller and more powerful, pushing the limits of air-cooled heat sinks. A competing constraint is that the thermal solutions need to be smaller and lighter, particularly for portable devices. A viable strategy to extend the limits of air-cooled heat sinks in a mass effective way is thermoelectric (TE) cooling. In general, the limiting COP of currently available TE materials requires that TE modules be operated at near optimum conditions. The conventional approach for optimizing TE modules ignores external irreversibilities, such as the heat sink temperature drop between the TE hot side and the ambient. The current study reviews two schemes for optimizing the operating current and compares their performance. The comparison between the COP maximizing current and the junction temperature minimizing current identifies where the two approaches yield the exact same performance. Performance regimes are then identified where the junction temperature minimizing approach provides an advantage over the COP maximizing approach. A significant extension of the current modeling activity over previous studies is allowing the TE module geometry to be optimized in addition to the operating current. When the TE module geometry is allowed to be optimized, it is found that using TE refrigeration operating at the junction temperature minimizing current will always have a performance benefit relative to a heat sink alone. The way this performance is achieved at higher heat loads is that the TE module elements must be made very thin.