Researchers from Laboratory for Thermal Technology (LTT) conducted an experimental study on the heater-side parameter influence on the growth of irreversible dry spots during the boiling crisis of the fluid FC-72, used for cooling of high-performance microelectronic applications. The results of the study were published in Applied Thermal Engineering (IF = 6.1).
Figure 1: Irreversible dry spot propagation on metal heaters of different materials and thickness.
The boiling crisis, initiated at high heat fluxes due to merging and propagation of dry spots on the surface, represents an operational limit of cooling by nucleate boiling. The event causes a rapid temperature increase, possibly leading to critical failure of especially thin elements or temperature-sensitive microelectronics, where dielectric fluids like FC-72 are used for cooling.
The presented results, obtained with high-resolution infrared thermometry, show that the growth of an irreversible dry patch is strongly affected by the heat diffusion process occurring within the thin heater. The dry spot propagation rate is found to be proportionally correlated with the thermal diffusivity of the heater and the volumetric heat dissipation rate achieved at the boiling crisis, the latter being inversely proportional to the heater thickness.
These results provide important new insights into dryout dynamics related to the boiling crisis in thin wall heat transfer devices, such as ultra-thin vapor chambers, heat pipes and heat exchangers.
