Thermofluid Characterization of Nanofluid Spray Cooling Combining Phase Doppler Interferometry with High-Speed Visualization and Time-Resolved IR Thermography

Figueiredo, Miguel; Marseglia, Guido; Moita, Ana S.; Panão, Miguel R. Oliveira; Ribeiro, Ana P. C.; Medaglia, Carlo Maria; Moreira, A.L.N.

doi:10.3390/en13225864

Cited by 14 publications

(17 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The properties depicted in Table 1 and other thermophysical properties, such as the viscosity and the thermal conductivity, can define relevant parameters present on pool boiling regimes, like the boiling heat transfer and the critical heat flux for nucleate pool boiling [ 34 ]. Except for the thermal conductivity and for the specific heat, all the other properties were evaluated experimentally in previous works [ 35 , 36 ], to validate the theoretical approaches used. The thermal conductivity was estimated by using the Maxwell model [ 37 ].…”

Section: Methodsmentioning

confidence: 99%

Pool Boiling of Nanofluids on Biphilic Surfaces: An Experimental and Numerical Study

et al. 2021

Self Cite

View full text Add to dashboard Cite

This study addresses the combination of customized surface modification with the use of nanofluids, to infer on its potential to enhance pool-boiling heat transfer. Hydrophilic surfaces patterned with superhydrophobic regions were developed and used as surface interfaces with different nanofluids (water with gold, silver, aluminum and alumina nanoparticles), in order to evaluate the effect of the nature and concentration of the nanoparticles in bubble dynamics and consequently in heat transfer processes. The main qualitative and quantitative analysis was based on extensive post-processing of synchronized high-speed and thermographic images. To study the nucleation of a single bubble in pool boiling condition, a numerical model was also implemented. The results show an evident benefit of using biphilic patterns with well-established distances between the superhydrophobic regions. This can be observed in the resulting plot of the dissipated heat flux for a biphilic pattern with seven superhydrophobic spots, δ = 1/d and an imposed heat flux of 2132 w/m2. In this case, the dissipated heat flux is almost constant (except in the instant t* ≈ 0.9 when it reaches a peak of 2400 W/m2), whilst when using only a single superhydrophobic spot, where the heat flux dissipation reaches the maximum shortly after the detachment of the bubble, dropping continuously until a new necking phase starts. The biphilic patterns also allow a controlled bubble coalescence, which promotes fluid convection at the hydrophilic spacing between the superhydrophobic regions, which clearly contributes to cool down the surface. This effect is noticeable in the case of employing the Ag 1 wt% nanofluid, with an imposed heat flux of 2132 W/m2, where the coalescence of the drops promotes a surface cooling, identified by a temperature drop of 0.7 °C in the hydrophilic areas. Those areas have an average temperature of 101.8 °C, whilst the average temperature of the superhydrophobic spots at coalescence time is of 102.9 °C. For low concentrations as the ones used in this work, the effect of the nanofluids was observed to play a minor role. This can be observed on the slight discrepancy of the heat dissipation decay that occurred in the necking stage of the bubbles for nanofluids with the same kind of nanoparticles and different concentration. For the Au 0.1 wt% nanofluid, a heat dissipation decay of 350 W/m2 was reported, whilst for the Au 0.5 wt% nanofluid, the same decay was only of 280 W/m2. The results of the numerical model concerning velocity fields indicated a sudden acceleration at the bubble detachment, as can be qualitatively analyzed in the thermographic images obtained in this work. Additionally, the temperature fields of the analyzed region present the same tendency as the experimental results.

show abstract

Section: Methodsmentioning

confidence: 99%

Pool Boiling of Nanofluids on Biphilic Surfaces: An Experimental and Numerical Study

et al. 2021

Self Cite

View full text Add to dashboard Cite

show abstract

“…Different nanofluids, composed by alumina and silver nanoparticles (with mass concentrations ranging between 0.5% and 2% m/m) combined with a base fluid of distilled water with 0.05% (m/m) cetyltrimethylammonium bromide -CTAB, were atomized using a tangential pressureswirl atomizer that creates a hollow cone spray. The atomizer, which was used in previous works [9], has a discharge orifice of 0.42mm in diameter and two opposing tangential inlet ports with a squared shape cross section of 0.6 x 0.6 mm 2 . It operates at an ejection pressure of 0.5 MPa, delivering a mass flow rate of 7 kg/h.…”

Section: Experimental Set-upmentioning

confidence: 99%

“…It operates at an ejection pressure of 0.5 MPa, delivering a mass flow rate of 7 kg/h. The resulting hollow-cone spray was characterized in terms of droplet size and velocity distributions using Phase Doppler Anemometry by Malý et al [11] and by Figueiredo et al [9]. The spray impacts on a stainless-steel foil AISI 304, with a width of 60 mm, length of 90 mm and thickness of 20m, which was heated by Joule effect, being the power provided by a HP 6274B DC power supply.…”

Section: Experimental Set-upmentioning

confidence: 99%

“…The surface is perfectly smooth within this vertical resolution. The wettability was characterized based on the measurement of the equilibrium contact angle, using an optical tensiometer (THETA from Attention), based on the sessile droplet method, as detailed for instance in [9]. The static contact angle was =86.5±6.4º for water on the AISI304 stainless steel surface, measured at 20ºC±3ºC.…”

Section: Experimental Set-upmentioning

confidence: 99%

“…Nanofluids have been extensively used in several flow geometries [5][6], but are still not much explored in spray cooling systems. In spray cooling applications, several authors report the difficulty in getting benefits from the surfactants addition to the fluids, to improve their stability, without disfavoring other fundamental physical fluid properties, as the bulk surface tension and the surface wettability that affect the nebulization process and the spray wall interaction event [7][8][9]. Also, many studies on spray cooling characterization still rely on the use of temperature sensors, such as thermocouples, to estimate the dissipated heat flux [10].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Heat transfer in nanofluid spray cooling of a solid heated surface for cooling systems in civil and military applications

Sanches¹,

Moita²,

Ribeiro³

et al. 2021

ICLASS

View full text Add to dashboard Cite

Interest in spray cooling has been increasing as an efficient thermal management technique for high power load systems such as electronics, e.g. in UAV's (Unmanned Aerial Vehicles), which have an important application in both civil and military applications. This work aimed to study the use of nanofluids as a way of improving sprays thermal performance. Nanofluids were prepared using, as base solution, distilled water with 0.05% (m/m) cetyltrimethylammonium bromide. Alumina nanoparticles were mixed at different concentrations: 0.5%, 1% and 2% (m/m). The effect of the shape of the nanoparticles was inferred using two different silver nanofluids, with 1% (m/m) concentration, one using spherical and the other using triangular particles. These nanofluids were sprayed using a hollow-cone atomizer, at two different heights from an AISI 304 stainless steel foil, heated by Joule effect. Thermal footprints of the sprays were acquired using infrared thermography and dissipated heat fluxes were calculated. When comparing the performance of silver nanofluids, the one with spherical particles resulted in slightly lower surface temperatures than the fluid with triangular particles. Heat transfer coefficients decreased with increasing thermal conductivity and dynamic viscosity of the nanofluids. On the other hand, a strong positive correlation was revealed with the specific heat capacity of the nanofluids. For the range of experimental conditions covered here, nanofluids have proven to increase the thermal performance of the spray.

show abstract

Thermofluid characterization of nanofluids in spray cooling

Marseglia

Sanches

Ribeiro

et al. 2022

Applied Thermal Engineering

View full text Add to dashboard Cite

Thermofluid Characterization of Nanofluid Spray Cooling Combining Phase Doppler Interferometry with High-Speed Visualization and Time-Resolved IR Thermography

Cited by 14 publications

References 39 publications

Pool Boiling of Nanofluids on Biphilic Surfaces: An Experimental and Numerical Study

Pool Boiling of Nanofluids on Biphilic Surfaces: An Experimental and Numerical Study

Heat transfer in nanofluid spray cooling of a solid heated surface for cooling systems in civil and military applications

Thermofluid characterization of nanofluids in spray cooling

Contact Info

Product

Resources

About