Experimental study on effects of surfactant and spray inclination on heat transfer performance in nonboiling regime

Singh, Sukhdeep; Kukreja, Rajeev

doi:10.1080/15567036.2021.2007313

Cited by 6 publications

(9 citation statements)

References 21 publications

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“…The details of the experimental test rig are given in the author's earlier work. 20 Figure 1(a) and (b) displays the schematic view and pictorial view of the experimental test rig built to conduct the experiments at various concentrations of nanofluid for a wide range of volumetric flux.…”

Section: Methodsmentioning

confidence: 99%

“…The details of the experimental test rig are given in the author's earlier work. 20 Figure 2 shows the pictorial view of the copper specimen, cartridge heaters and test heater assembly. Four holes were drilled at the bottom of the copper specimen for fixing cartridge heaters as heat source.…”

Section: Test Facilitymentioning

confidence: 99%

“…Sizing and dimensions of the copper heater block and positioning of various thermocouples in the heater block have been provided in the author's earlier work. 20…”

Section: Test Facilitymentioning

confidence: 99%

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Experimental study on spray cooling heat transfer enhancement using MWCNT and TiO₂ hybrid nanofluid

Singh

Kukreja

2022

Proceedings of the Institution of Mechanical Engineers, Part E:

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In the present study, two nanofluids namely Multi-walled carbon nanotubes and Titanium dioxide dispersed in distilled water, have been used with three different concentrations; 0.1%, 0.2%, and 0.3% by volume, to investigate heat transfer enhancement in spray cooling applications. A square copper specimen of 10 mm2 has been spray cooled with a volumetric flux of 2.5 cm3/cm2s using a 0.4 mm diameter pressure nozzle. The results revealed that the average heat transfer coefficient and corresponding critical heat flux enhanced significantly at 0.2 vol% for both nanofluids in contrast to distilled water. The results showed an improvement of 21.9% and 26.3% in heat transfer coefficient for Multi-walled carbon nanotubes and Titanium dioxide nanofluid, respectively. The effect of hybrid nanofluid in various concentrations has also been investigated on heat transfer performance. The results obtained showed a maximum value of 425 W/cm2 for critical heat flux and 4.42 W/cm2K for heat transfer coefficient, with a heat transfer coefficient improvement of nearly 40.31% in comparison to distilled water. This results in an enhancement ratio of 1.6 for critical heat flux and 1.4 for heat transfer coefficient. In contrast to single nanoparticle nanofluid, the hybrid nanofluid indicated a moderate improvement in heat transfer coefficient of 11.7% and 7.8% for Multi-walled carbon nanotube and Titanium dioxide nanofluids, respectively. It has been observed that heat transfer performance was first enhanced and then declined as the volume fraction increased from 0.1% to 0.3% for all the nanofluids.

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Section: Methodsmentioning

confidence: 99%

Section: Test Facilitymentioning

confidence: 99%

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Experimental study on spray cooling heat transfer enhancement using MWCNT and TiO₂ hybrid nanofluid

Singh

Kukreja

2022

Proceedings of the Institution of Mechanical Engineers, Part E:

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“…where q ′′ is the heat flux, k is the thermal conductivity, T 2,a and T 1,a are the thermocouple locations in the middle plane and x 2 is the distance between the two thermocouple planes. The average temperature of the test surface may be evaluated from the equation given below 24 :…”

Section: Data Acquisition Systemmentioning

confidence: 99%

Effect of binary mixed-surfactants and hybrid nanofluid on spray cooling heat transfer

Singh

2022

Proceedings of the Institution of Mechanical Engineers, Part E:

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The present study emphasizes the spray-cooling enhancement of a copper heater block of 10 mm2 cross-sectional area with binary mixed surfactant based fluid and hybrid nanofluid using a pressure swirl nozzle with an orifice size of 0.51 mm. The experiments have been carried out at two distinct fluid input temperatures of 27 °C and 42 °C, with a volumetric flux of 3.50 cm3/cm2s. Polyvinyl pyrrolidone (polymer surfactant), Sodium dodecyl sulfate (an anionic surfactant), Tween-20 (a nonionic surfactant) have been used as binary mixed surfactant systems in distilled water. The best performance has been obtained with SDS:Tween-20, which resulted in a maximum heat flux of 264 W/cm2 and a heat transfer coefficient of 3.59 W/cm2K. When compared to distilled water, the heat transfer coefficient increased by 32.2%, but only by 25.2% and 18.1% with PVP:Tween-20 and SDS:PVP surfactant solutions. Further, the effect of a hybrid nanofluid, which is a colloidal mixture of Titanium dioxide (TiO2) and MWCNTs (multi-walled carbon nanotubes) in distilled water, has been studied to better understand spray cooling heat transfer enhancement. Heat transfer was first enhanced by the hybrid nanofluid and then decreased as the volume concentration was increased from 0.1% to 0.3%. A maximum heat flux of 234 W/cm2 and a heat transfer coefficient of 3.15 W/cm2K has been achieved, with a heat transfer coefficient improvement of nearly 27.3% compared to distilled water. However, the mixed surfactant system outperformed, giving nearly 12.8% improvement in heat flux values. It has been observed that low surface tension resulted in high heat transfer rates. Furthermore, the effect of 15 °C subcooling on heat transfer performance has been investigated. A new correlation to find Nusselt number is proposed in terms of Reynolds number, Weber number and Prandtl number with a mean absolute error of 7.16%.

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“…Different regimes have been observed during spray cooling at various wall temperatures and impact parameters. These regimes include the nucleate boiling regime [9,16], characterized by the heterogeneous nucleation of multiple bubbles on the wetted part of the solid surface; the transition regime, when the substrate surface is not uniformly wetted due to the percolation of the vapor in channels formed by the coalescence of the bubbles [17]; the film boiling regime [10,18,19], characterized by the complete rebound of the impacting drops; and the thermal atomization regime, accompanied by the generation of an intensive flow of fine secondary drops [20] in the case of high impact velocities of the primary drops. In order to simplify physical modeling of the associated thermal-hydraulic phenomena, a spray can be approximated as an aggregate of individual dispersed droplets, which means that mechanisms governing the impact of individual drops onto a heated surface need to be well understood as well [18].…”

Section: Introductionmentioning

confidence: 99%

Spray impact onto a hot solid substrate: Film boiling suppression by lubricant addition

et al. 2023

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Spray cooling of solid substrates is one of the methods used in various industrial processes such as forging, quenching or other metallurgical applications, electronics, pharmaceutical industry, medicine, or for cooling of powerful electrical devices. Spray cooling is governed by various hydrodynamic and thermodynamic processes, like drop impact, heat conduction in the substrate and convection in the spreading drops, and different regimes of boiling. The problem of modeling spray cooling becomes even more challenging if the liquid is multicomponent. The presence of components with various physicochemical properties (surfactants, binders, dispersed particles, etc.) can significantly affect the entire process of spray impact, as well as the outcome of the known cooling regimes and could lead to a formation of a thin deposited layer on the substrate. In this experimental study, spray impact onto a substrate, initially heated to temperatures significantly exceeding the liquid saturation point, is visualized using a high-speed video system. The heat transfer associated with spray impact is characterized using an array of thermocouples installed in a thick metal target. As a working fluid, a mixture of a distilled water and industrial white lubricant was used. It is observed that the presence of very small concentrations of lubricant augments the heat flux dramatically, particularly at high wall temperatures, at which usually film boiling is observed for spray cooling by using distilled water. Three main mechanisms lead to the increase of heat flux and shift of the Leidenfrost point. They are caused by the significant viscosity increase of the evaporating lubricant solutions, by an increase of the substrate wettability and by the emergence of stable liquid sheets between bubbles, preventing their coalescence and percolation of the vapor channels.

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Experimental study on effects of surfactant and spray inclination on heat transfer performance in nonboiling regime

Cited by 6 publications

References 21 publications

Experimental study on spray cooling heat transfer enhancement using MWCNT and TiO₂ hybrid nanofluid

Experimental study on spray cooling heat transfer enhancement using MWCNT and TiO₂ hybrid nanofluid

Effect of binary mixed-surfactants and hybrid nanofluid on spray cooling heat transfer

Spray impact onto a hot solid substrate: Film boiling suppression by lubricant addition

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Experimental study on effects of surfactant and spray inclination on heat transfer performance in nonboiling regime

Cited by 6 publications

References 21 publications

Experimental study on spray cooling heat transfer enhancement using MWCNT and TiO2 hybrid nanofluid

Experimental study on spray cooling heat transfer enhancement using MWCNT and TiO2 hybrid nanofluid

Effect of binary mixed-surfactants and hybrid nanofluid on spray cooling heat transfer

Spray impact onto a hot solid substrate: Film boiling suppression by lubricant addition

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Product

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Experimental study on spray cooling heat transfer enhancement using MWCNT and TiO₂ hybrid nanofluid

Experimental study on spray cooling heat transfer enhancement using MWCNT and TiO₂ hybrid nanofluid