Impact of Silica Nanofluid Deposition on Thermosyphon Performance

Kujawska, A.; Mulka, R.; Buschmann, Matthias; Królicki, Z.; Zajączkowski, Bartosz

doi:10.1080/01457632.2020.1818413

Cited by 8 publications

(7 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…After finishing all experimental points, the working fluid was removed from the device and it has been once again evaluated. More details on the experimental setup and the procedure, as well as detailed results can be found in [15].…”

Section: Methodology a Investigated Working Fluidsmentioning

confidence: 99%

“…Water-based silica nanofluid (Fig. 1) prepared by Fraunhofer-Institut für Keramische Technologien und Systeme IKTS was previously used as a working fluid in a thermosyphon [15]. The raw material (SIPERNAT 22S) was dispersed unfractionated with higher concentration and then diluted to a concentration of 2% vol.…”

Section: Methodology a Investigated Working Fluidsmentioning

confidence: 99%

“…Literature offers several comprehensive reviews on thermosyphons and heat pipes using nanofluids as working fluids [9][10][11][12][13]. Deeper look into thermosyphons working with nanofluids, including graphene-based and silica particles has been presented in our earlier papers [14,15], and thus are not repeated here. Many studies show that nanofluids may improve heat transfer capabilities of the thermosyphon [7,9,14,[16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

“…Boiling heat transfer is influenced by many parameters that can be divided into three groups: thermophysical properties of the working fluid, characteristics of the heater surface, and near surface hydrodynamics. During the boiling of nanofluids, nanoparticles tend to deposit on the heater surface (evaporator in thermosyphon), which alters the characteristics of this surface and nearsurface hydrodynamics [23][24][25][26][27][28][29], and it was closely analysed in detail in our previous works [7,14,15,20]. This paper focusses on the third group -thermophysical properties of working fluids (surface tension) and their interaction with the heater surface (wettability) with the aim of investigating whether these properties change over time during the operation.…”

Section: Introductionmentioning

confidence: 99%

“…There is an endless number of nanofluids combinations, including used nanoparticles, base fluid, concentration, size, surfactant, etc. In our previous studies [7,14,15] we analysed different types of nanofluids with respect to application in thermosyphon. The nanofluids were chosen to address various research concerns, such as whether high thermal conductivity (gold, graphene oxide) and high specific surface area (nanohorns, graphene oxide) of nanoparticles are crucial for boiling applications, the impact of film-forming properties (silica), or the impact of surfactant addition (water solution of sodium dodecyl sulfate).…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

The effect of boiling in a thermosyphon on surface tension and contact angle of silica and graphene oxide nanofluids

Kujawska

Mulka

Hamze

et al. 2021

Colloids and Surfaces A: Physicochemical and Engineering Aspect

Self Cite

View full text Add to dashboard Cite

Thermosyphons are heat transfer devices characterized by high efficiency due to simultaneous phase changes occurring in the evaporation-condensation cycle of working fluid. One of the most promising solutions to enhance their heat transfer capacity of the device is the use of nanofluids -suspensions of particles with at least one dimension below 100 nm. It was determined that nanofluid does not influence the work of thermosyphons condenser section and the focus should be put on the boiling process in the evaporator section. During boiling, nanoparticles tend to deposit on the heater's surface, what alters characteristics of this surface and near surface hydrodynamics. This changes the appearance of nanofluid, but the precise effect on how the deposition of particles affects the properties of nanofluid is unknown. Changes in surface tension and wettability affect boiling regimes (e.g. reduced surface tension reduces the size of departing bubbles and inhibits geysering), and efficiency of heat transfer through the device. Understanding of those parameters is crucial for the development of appropriate models describing heat transfer in thermosyphon working with nanofluids. The main goal of this study is to determine surface tension and contact angle of nanofluids based on silica nanoparticles and nano-sized graphene oxide flakes before and after the experimental boiling cycle in the thermosyphon. Results show that, in comparison with water, silica nanofluid (2 vol.%) is characterized by lower surface tension and contact angles on both analysed surfaces. After-use silica nanofluid exhibited noticeably higher averaged surface tension and smaller contact angles in comparison to the fresh working medium. The change was most likely due to the decreased concentration caused by the deposition of nanoparticles during the thermosyphon operation. Still, the differences between before-use and after-use samples were smaller than the measurement uncertainties. Before-use graphene oxide nanofluid already showed surface tension and contact angle similar to water due to low concentration of graphene flakes (0.1 g/L). Consequently, the properties of after-use graphene oxide fluid were also not much different from water. Additional measurements of surface tension for graphene oxide nanofluid with and without addition of sodium dodecyl sulfate surfactant allowed to differentiate the effects caused by graphene flakes and surfactant. The surfactant reduced the surface tension of the nanofluid, but the change was smaller than in case of surfactant addition to pure water.

show abstract

Section: Methodology a Investigated Working Fluidsmentioning

confidence: 99%

Section: Methodology a Investigated Working Fluidsmentioning

confidence: 99%