Multi-stage thermoelectric coolers for cooling wearables

Over the last decade, there has been significant interest in the use of thermoelectric coolers (TECs) in cooling wearables. While there has been notable work on optimizing single-stage TECs for use against human skin, much less attention is given to multi-stage TECs. In this contribution, analytical computations are performed to show that multi-stage TECs can achieve lower cold side temperatures while maintaining the coefficient of performance as compared to single-stage TECs when used against human skin. The findings are confirmed with detailed FEA analysis and experiments. The results therefore imply that multi-stage TECs have the potential of providing more cooling sensation to the human skin, while maintaining the power required per unit cooling power provided. This paper provides a detailed parametric studies on how key design parameters of the TECs (number of stages, current ratio, fill factor, aspect ratio and leg area) affect the performance of the multi-stage TECs. A guideline on the optimal design parameters is provided to guide the design of multi-stage TECs for use in cooling wearables.