Thermal performance of an aluminum closed loop pulsating heat pipe copper wire insert.

Abstract

The Closed Loop Pulsating Heat Pipe (CLPHP), a device pivotal in thermal management systems, is scrutinized for its performance across varying filling ratios (50% and 60%) and with different working fluids: ethanol, methanol, ethylene glycol, and Acetone. Ethanol emerges as a superior working fluid, demonstrating robust heat transfer capabilities at both filling ratios, with optimal performance at 60% due to favorable phase change and pulsation dynamics. Methanol, while showing enhanced heat dissipation at a 60% ratio, runs the risk of premature dry-out, where the liquid phase fails to return to the evaporator a critical system limitation. Ethylene glycol's higher viscosity favors a 50% filling ratio, avoiding the suboptimal heat transfer that higher ratios incur. With its low boiling point and high thermal conductivity, Acetone excels particularly at 60%, maintaining lower thermal resistance without the dry-out issues prominent at lower fillings. In board-level applications, where spatial, gravitational, and integration considerations are paramount, the design of the CLPHP must adeptly navigate these constraints. Failures such as dry-out or thermal saturation, exacerbated by excessive heat input and poor fluid dynamics, highlight the need for a careful balance between thermal input and fluid properties. The study recommends advanced wick structures and precise fluid management in future CLPHP designs to enhance capillary action and efficiency. This comprehensive understanding is vital for optimizing CLPHP deployment in high-heat-flux applications, both exis