(Invited) Peltier Supercooling with Isosceles Current Pulses: Cooling an Object with Internal Heat Generation

Abstract

Applying an electrical current pulse enables a transitory state in which the cold junction of a Peltier couple reaches temperatures below that obtained with an optimized steady-state current. This is known as supercooling. This supercooling is followed by a period of superheating. It has been shown for optimized isosceles triangle shaped current pulses, the sum of supercooling and superheating can provide a net cooling advantage. In most cases, supercooling has been studied as a standalone couple and not as a system and only from the perspective of cold side temperature. The objective of this paper is to gain insight about the sensitivity of the system performance metrics of COP, power consumption, cold junction cooling rate ( Qc ) and average cooled heat generating object temperatures during pulsed operation. A comprehensive system variable parametric study was performed. The study used a system model that utilized electrical-thermal analogies in SPICE. It was demonstrated that Qc over an entire pulse event can be improved over I max steady operation but not steady Iopt operation. Qc can be improved over I opt operation only during the early part of the pulse event. COP is reduced during a pulse due to the fast time constant of power consumption relative to Qc . Time delayed Joule heat and Seebeck voltage contribute to further lowering of COP. During part of the pulse transient, lower performance interface materials improved Qc and COP which may mean interface resistance is an optimizable parameter for transient operation.