Thermal Performance of Pulsating Heat Stripes Built With Plastic Materials

Abstract

A low-cost, flexible pulsating heat pipe (PHP) was built in a composite polypropylene sheet consisting of three layers joint together by selective laser welding, to address the demand of heat transfer devices characterized by low weight, small unit thickness, low cost, and high mechanical flexibility. A thin, flexible, and lightweight heat pipe is advantageous for various aerospace, aircraft, and portable electronic applications where the device weight, and its mechanical flexibility are essential. The concept is to sandwich a serpentine channel, cut out in a polypropylene sheet and containing a self-propelled mixture of a working fluid with its vapor, between two transparent sheets of the same material; this results into a thin, flat enclosure with parallel channels hence the name “pulsating heat stripes” (PHS). The transient and steady-state thermal response of the device was characterized for different heat input levels and different configurations, either straight or bent at different angles. The equivalent thermal resistance was estimated by measuring the wall temperatures at both the evaporator and the condenser, showing a multifold increase of the equivalent thermal conductance with respect to solid polypropylene