The progression towards more functional and compact electronics has increased heat emissions from electronic chips. Boiling and condensation offer high heat transfer coefficients by dissipating heat through the latent energy of liquid-vapor phase change. Consequently, cooling devices utilizing boiling and condensation are highly desirable. Thermosyphons, as gravity-assisted wickless heat pipes, are cost-effective in dissipating heat through boiling and condensing the working fluid.
This study focuses on developing novel configurations of flat thermosyphon heat sinks and investigating their thermal performance. Initially, the thermal performance of a compact flat thermosyphon is examined with various working fluids, filling ratios, and the number of heat sources. Subsequently, the influence of different evaporator and condenser surface wettabilities combinations on the flat thermosyphon's thermal performance is explored. It is noted that appropriate surface wettability modifications significantly enhance the flat thermosyphon's thermal performance. Pool boiling experiments employing infrared thermography and high-speed imaging provide insights into boiling heat transfer enhancement. Saturated pool boiling experiments are conducted on copper minichannel and flat surfaces at atmospheric pressure, with water as the working fluid. The critical heat flux and heat transfer coefficient are utilized to characterize the thermal performance of the boiling surface. Minichannel-1 and Minichannel-2, having square cross-sections with side lengths of 1 mm and 2 mm, respectively, are tested in the experiments. Based on the insights gained from the studies on compact flat thermosyphons and pool boiling, a novel integrated flat thermosyphon heat sink (IFTHS) is developed. The IFTHS incorporates a condenser with integrated hollow fins, utilizing the inner surface of the fins for condensation and the outer surface for air-side convective cooling. The thermal performance of the IFTHS is investigated at various filling ratios and further enhanced by integrating an evaporator with minichannels and a superhydrophobic condenser. The IFTHS exhibits better thermal performance, weight reduction, and energy savings than conventional heat sinks, making it a promising and cost-effective solution for energy-efficient chip-level thermal management in data centers. This talk provides a detailed discussion on the development and thermal performance of novel configurations of flat thermosyphon heat sinks.