Transfer processes in the thermosyphon employing graphene oxide and silica nanofluids
Agnieszka Wlazlak1, Bartosz Zajaczkowski1, Zbigniew Krolicki1, Michal Woluntarski2, Matthias Buschmann3.
1Wroclaw University of Science and Technology, Wroclaw, Poland; 2Institute of Electronics Materials Technology, Warsaw, Poland; 3Institut für Luft- und Kältetechnik, Dresden, Germany
Thermosyphons, as passive heat transfer devices, often assist heat pumps and refrigeration systems. Employing nanoadditives enhance their heat transfer capabilities and in consequence improve performance of thermal systems. Here, we analyse thermal resistances and time-dependent boiling characteristics of devices filled with water-based silica and graphene oxide nanofluids, known to enhance heat transfer capabilities of water/glycol solutions. The experimental campaign in this work encompassed source temperatures 40-85°C. Nanofluids reduced thermal resistance of the device at low heat loads. The impact of nanoadditives was restricted to the evaporator section and correlated with the formation of porous layer on the heater's surface. Additionally, nanofluid affected a pseudo-steady state geyser boiling. The frequency and intensity of geyser events depended on the type of nanofluid, surfactants, and temperatures of heat sources.
