Performance of nitrogen pulsating heat pipes as passive thermal switches in a redundant cryocooler application

A novel redundant cryocooler system, featuring two cold heads linked via separate nitrogen pulsating heat pipe (PHP) thermal switches to a common plate, is developed and performance tested. The setup allows the plate be maintained at design temperature when one of cryocoolers inactive by leveraging low conductivity static vapor in associated dry PHP as insulation from warm cryocooler. operate passively require no mechanical actuation, inherently offering highly reliable switching mechanism. load, effective conductivity, conductance, evaporator temperature, condenser measurements are presented for range fill ratios applied loads. tested PHPs can transfer least 16 W before dryout have conductivities ON OFF switch states ranging 10,000 W/m-K 55,000 8 50 W/m-K, respectively. Thermal characterized ratio – its conductance state that demonstrated approach about 2500 PHPs. parasitic load through (about 0.6 W) found 4 percent maximum capacity W).