Transient supercooling performance of thermoelectric coolers with a continuous double current pulse

In this work, the transient supercooling performance of thermoelectric coolers is numerically investigated via a three-dimensional, multiphysics, and transient model. The particular focus is placed on how to increase the holding time of supercooling state to meet some specific cooling requirements. A new concept of effective cooling temperature line is proposed to evaluate the supercooling performance. On the basis of this concept, the frequently used holding time of supercooling state is replaced by an effective holding time, t_eff-hold. As a reference baseline, the transient supercooling performance is first evaluated under a single current pulse and the largest t_eff-hold is determined by searching for the optimal pulse width and amplitude. Subsequently, the supercooling performance and the effective holding time are evaluated under a continuous double current pulse whose shape can be characterized by the pulse width (τ₁) and amplitude (P₁) of the first pulse, the pulse width (τ₂) and amplitude (P₂) of the second pulse, and the initial current (I_ini,2) of the second pulse. The results show that among the five parameters I_ini,2 is the most dominant parameter to achieve a larger t_eff-hold. Only when I_ini,2 is higher than the initial current of the first pulse, employing a double pulse can yield a larger t_eff-hold than employing the optimal single pulse. The results also demonstrate that with a proper I_ini,2 the value of t_eff-hold can be further prolonged by optimizing τ₁, τ₂, P₁, and P₂, and the largest t_eff-hold for the optimal double pulse is increased by 59.8%, as compared with that of the optimal single pulse. Finally, the principles for selecting parameters of a double current pulse are discussed.