Nestacionarno temperaturno polje in dinamika rasti parnega mehurčka pri vrenju na grelcu z majhno toplotno kapacitivnostjo in z različnimi površinami

This work investigates fundamental multi-scale phenomena occurring during pool boiling on thin heat dissipators with low thermal capacitance. Experimental studies were conducted in carefully controlled boiling environments, where stable, nearly steady-state bubble life cycles at isolated nucleation sites were observed. To achieve a comprehensive visualization of boiling processes, synchronized high-speed video, infrared thermography, and micro-thermocouple measurements were employed. Artificial nucleation sites were created on the tested surfaces through a combination of laser texturing and hydrophobization techniques. The influence of the heater’s thermophysical properties on local heat transfer behavior was demonstrated, particularly during the rewetting of the bubble footprint on the wall. Their effects on the liquid rewetting temperature were clarified, providing insights into a previously unexplored aspect of the process. Furthermore, a detailed force balance analysis was performed to examine the dynamic behavior of vapor bubbles at the wall. Building upon this, the process of bubble growth was analyzed, revealing important limitations of existing models based on finite liquid thermal boundary layers. A novel correction was proposed to accurately capture the experimentally observed trend in bubble growth. The knowledge gained from the force balance approach was further utilized in the analysis of data collected aboard the International Space Station, where the dual effects of auxiliary electric fields on vapor bubble departure in microgravity were elucidated. Finally, the boiling investigations were extended to the boiling crisis, focusing on the role of the wall’s thermophysical properties in the propagation of irreversible dry spots.