Drawn Polymer Fiber Recuperative Heat Exchangers

Abstract

Polymer microchannel heat exchangers for use in cryocooler applications have been developed. These heat exchangers are manufactured using a thermal drawing process where a bulk polymer preform is heated and stretched. The process results in channels with a characteristic dimension of 50-100 µm and with an overall length of many meters. The drawn heat exchangers are lightweight, flexible, and have a large surface-area-to-volume ratio. Initial tests on a Joule-Thomson cryocooler with a heat exchanger of overall dimension of 2.5mm x 2.5mm x 400mm with nitrogen as a working fluid were performed. Nitrogen was successfully liquefied with a mass flow rate of 34 mg/s and cooling power of 200 mW at 80 K.