Geyser boiling in a thermosyphon with nanofluids and surfactant solution

Kujawska, A.; Zajączkowski, Bartosz; Wilde, L.M.; Buschmann, Matthias

doi:10.1016/j.ijthermalsci.2019.02.001

Cited by 29 publications

(12 citation statements)

References 41 publications

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“…Nanofluids are defined as suspensions of nano-objects with at least one dimension smaller than 100 nm [5], while nanoparticles indicate nano-objects with all spatial dimensions smaller than 100 nm [6]. The term 'nanoparticle' is commonly used for both nano-objects and nanoparticles [5,7,8], and is used in a similar context in this paper.…”

Section: Introductionmentioning

confidence: 99%

“…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]. Literature agrees that the effect of nanofluids on the condenser section is negligible [9,[20][21][22], and thus focus should be put on the evaporator section and the boiling process.…”

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 3 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

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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.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 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

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“…Liang et al 21 tested the thermal characteristics of the mini heat pipe, which was rotated at rotational speeds ranging from 1000 to 3000 rpm and power inputs ranging from 2.5 to 30 W. The results showed that the circumferential temperature variance improved with the increase of the rotational rates and heat input. Kujawska et al 22 determined the impact of several nanofluids on the thermal performance of geyser boiling (ie, closed thermosiphon). Their results showed that chemical stabilizers have a greater effect on thermal performance than nanoparticles.…”

Section: Introductionmentioning

confidence: 99%

Assessment of heat transfer and flow characteristics of a two‐phase closed thermosiphon

Ahmed

Jubori

2020

Heat Trans

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In this study, comprehensive modeling and simulations were developed and carried out to perform the investigation of the thermal performance of the enclosed thermosiphon through pool boiling in the evaporator sector and the condensation of the liquid film in the condenser part. To simulate these phenomena, the volume of fluid model was utilized. The simulation modeling using the computational fluid dynamics (CFD) technique was validated with existing experimental results, and a good agreement was reached. The simulation results were presented and evaluated in terms of temperature profiles and contours, the volume of fraction contours, and velocity vector distribution. Moreover, the thermal performance (ie, the heat transfer coefficient and thermal resistance) through the thermosiphon operation was analyzed. From the simulation results, it is found that the thermosiphon performance can be improved by the tilt angle and fill ratio. The results indicated that the optimal performance (ie, a high heat transfer coefficient and a low thermal resistance) was attained at a power input of 250 W, tilt angle of 90°, and fill ratio of 0.5. The established CFD simulations effectively predicted the formation of two‐phase flow pattern and boiling and condensation zones with water at a low power input, termed as geyser boiling.

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Thermal analysis and thermo-hydraulic characteristics of zirconia–water nanofluid under a convective boiling regime

Sarafraz

Tlili

Tian

et al. 2019

J Therm Anal Calorim

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Geyser boiling in a thermosyphon with nanofluids and surfactant solution

Cited by 29 publications

References 41 publications

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

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

Assessment of heat transfer and flow characteristics of a two‐phase closed thermosiphon

Thermal analysis and thermo-hydraulic characteristics of zirconia–water nanofluid under a convective boiling regime

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