Determination of geyser events in a thermosyphon working with graphene oxide nanofluid
Two-phase closed thermosyphons are efficient passive devices with potential for using in many heat transfer applications. One of the boiling regimes that may occur is the geyser boiling. It is a repetitive irregular process of pushing liquid without its previous evaporation in the direction of condenser. Although it does not affect time-averaged thermal performance of the device, it causes additional mechanical load and shortens the life-time of the device. Unfortunately, geysering is not well investigated, thus no precise definition exists. This paper focuses on the process of data reduction that leads to geyser boiling detection. It may be applied for various working fluids and operating conditions. Two parameters are crucial for recognizing geyser events from the background noise (pressure variations followed by the geyser): the minimum amplitude of pressure increase and waiting period between ensuing events. We compared two working fluids: water and graphene oxide nanofluid. In general, with increase of heat flux the frequency of geysers increases and their amplitude decreases.