Search for: All records

Oscillating heat pipes (OHPs) represent a promising advancement over traditional heat pipes, yet their operational boundaries, especially for long OHPs, remain insufficiently understood. This study investigates the impact of varying adiabatic length, channel diameter, and fill ratio on thermal performance, crucial for assessing their suitability for engineering applications like spacecraft thermal management. Three long OHPs, ranging from 451 mm to 770 mm in total length, were subjected to multiple performance tests, employing channel diameters of 1.1 mm and 1.9 mm, along with adiabatic lengths of 305 mm and 610 mm. The experimental setup involved mounting the OHPs onto a testbed, monitored by nine K-type thermocouples. The tests, conducted horizontally to eliminate gravity-assistance, revealed that thermal performance is significantly influenced by channel diameter, adiabatic length, and fill ratio. Notably, optimal performance was observed at a 50% fill ratio, while reductions in diameter hindered start-up at a 70% fill ratio and failed to start-up at 30% fill ratio. These findings highlight the limitations of long OHPs, which is crucial to determine the limits of their applicability and dimensional constraints.