Transient Thermal Behavior of a Neon Pulsating Heat Pipe (PHP)

Pulsating heat pipes (PHPs) are more and more studied as thermal link to cool down superconducting magnet using cryocoolers. They are passive two-phase heat transfer devices where the condenser part is connected to the evaporator part by a long capillary tube bent into many U-turns. For years, only small pulsating heat pipe (less than 300 mm long) have been studied at cryogenic temperature, using N-2, He, Ne, and H-2 as working fluids. We have developed a meter-long horizontal PHP for future superconducting magnets that would be effective both on earth or in space. All the experiments have been performed using neon as working fluid with a fixed heat load on the evaporator part. PHP with neon operates at a temperature around 30 K which makes these devices interesting for cooling down future HTS magnet. This paper presents the results and analyses of the PHP thermal behavior after a sudden high increasing of the heat load on the evaporator part. These information are necessary to foresee the thermal behavior and operating limits of such a device during the quench of a superconducting magnet. This paper shows that neon PHP can function normally with an important supplementary heat generated on the evaporator part.