Enhancing Predictive Capabilities of Pulsating Heat Pipes (PHPs) Through Validation with Diverse Configurations

Pulsating Heat Pipes (PHPs) are passive thermal transport devices characterized by a serpentine microchannel loop that traverses back and forth from its evaporator and condenser zones. Within this microchannel, liquid slugs and thin liquid films trapped between the wall and elongated bubbles undergo evaporation in the heated evaporator, with the resulting volumetric expansion pushing the adjacent liquid to flow and leading to perpetual oscillations within the device.Despite their now growing significance in thermal management applications, existing PHP models have demonstrated limited predictive capabilities. Furthermore, the empirical values assigned to evaporation and condensation heat transfer coefficients often lack a solid physical basis. For accurate and more widespread implementation of PHPs into industrial cooling applications, such an accurate and broadly validated design code is the key.The one-dimensional transient numerical code developed by JJ Cooling Innovation for PHPs has recently seen its thermal model updated and rigorously validated, exhibiting high accuracy across a range of heat loads (up to 250 W). The predictions of the model align with experimental data, achieving an impressive 97% accuracy within a ±30% error margin (typically a good measure in prediction of two-phase heat transfer).The validation process was conducted using a copper tube PHP featuring a 19-turn configuration with an internal diameter of 2.0 mm and a tube pitch of 12 mm. A microchannel water-cooling plate, maintained at an inlet temperature of 20°C, was employed on the condenser side. Tests were carried out in vertical and horizontal orientations, using R1233zd(E) as the working fluid.Building on this successful validation, the scope of our project expands to include flat micro-channel PHPs with various lengths, orientations, filling ratios and two distinct cooling methods—air and water cooling of the condenser zone. This further validates the current numerical model under diverse operating conditions, extending its applicability and enhancing the understanding of PHP behavior.By systematically evaluating PHP performance across a broader spectrum of configurations, this research contributes to advancing the predictive capabilities of PHP models and their potential for efficient thermal management in various applications.