Pulse -Driven Refrigeration: Progress and Challenges

A v arian t of the pulse thermal loop is proposed for use in terrestrial and space thermal management systems. The two -phase device is driven by a pair of constant volume boilers feeding an ejector which entrains secondary flow from an evaporator. A high -temperature load from battery -packs or onboard electronics can be used to pressurize the boilers while the evaporator draws heat from a cooling load in the vapor compression loop . Two configurations of the hybrid prototype are described , both running on R 134a . A uniq ue feature of the system is unsteady flow through the ejector, which leads to challenges in entraining working fluid from the vapor compression branch. Preliminary test data suggest that secondary flow entrainment is possible under pulsatile flow condition s, although pressure drop through the ejector negatively affects operation of the outer driving loop. An alternate configuration is proposed to overcome operational challenges, and preliminary results from a numerical simulation of unsteady flow through th e ejector are presented .