Nanofluids Characterization for Spray Cooling Applications

In this paper the mathematical and physical correlation between fundamental thermophysical properties of materials, with their structure, for nanofluid thermal performance in spray cooling applications is presented. The present work aims at clarifying the nanofluid characteristics, especially the geometry of their nanoparticles, leading to heat transfer enhancement at low particle concentration. The base fluid considered is distilled water with the surfactant cetyltrimethylammonium bromide (CTAB). Alumina and silver are used as nanoparticles. A systematic analysis addresses the effect of nanoparticles concentration and shape in spray hydrodynamics and heat transfer. Spray dynamics is mainly characterized using phase Doppler interferometry. Then, an extensive processing procedure is performed to thermal and spacetime symmetry images obtained with a high-speed thermographic camera to analyze the spray impact on a heated, smooth stainless-steel foil. There is some effect on the nanoparticles’ shape, which is nevertheless minor when compared to the effect of the nanoparticles concentration and to the change in the fluid properties caused by the addition of the surfactant. Hence, increasing the nanoparticles concentration results in lower surface temperatures and high removed heat fluxes. In terms of the effect of the resulting thermophysical properties, increasing the nanofluids concentration resulted in the increase in the thermal conductivity and dynamic viscosity of the nanofluids, which in turn led to a decrease in the heat transfer coefficients. On the other hand, nanofluids specific heat capacity is increased which correlates positively with the spray cooling capacity. The analysis of the parameters that determine the structure, evolution, physics and both spatial and temporal symmetry of the spray is interesting and fundamental to shed light to the fact that only knowledge based in experimental data can guarantee a correct setting of the model numbers.

[1]  M. A. Amalina,et al.  Optimization of ultrasonication period for better dispersion and stability of TiO2-water nanofluid. , 2017, Ultrasonics sonochemistry.

[2]  Peter John Kay,et al.  Transient fuel spray impingement at atmospheric and elevated ambient conditions , 2012 .

[3]  A. Moita,et al.  Effect of nanoparticles concentration on the characteristics of nanofluid sprays for cooling applications , 2018, Journal of Thermal Analysis and Calorimetry.

[4]  Xianglong Luo,et al.  Investigation on crystallization of TiO2–water nanofluids and deionized water , 2012 .

[5]  Luis Lugo,et al.  Current trends in surface tension and wetting behavior of nanofluids , 2018, Renewable and Sustainable Energy Reviews.

[6]  T. Krishnakumar,et al.  Heat transfer studies on ethylene glycol/water nanofluid containing TiO2 nanoparticles , 2019, International Journal of Refrigeration.

[7]  Sławomir Pietrowicz,et al.  A review of the capabilities of high heat flux removal by porous materials, microchannels and spray cooling techniques , 2016 .

[8]  R. Kumar,et al.  A review on thermophysical properties of nanofluids and heat transfer applications , 2017 .

[9]  D. Bonn,et al.  How surfactants influence the drop size in sprays from flat fan and hollow cone nozzles , 2019, Physics of Fluids.

[10]  A. Moita,et al.  Application of bioinspired superhydrophobic surfaces in two-phase heat transfer experiments , 2017 .

[11]  A. Srivastava,et al.  Understanding the temperature dependence of thermo-physical properties of nanofluid suspensions using non-intrusive dynamic measurements , 2018, Experimental Thermal and Fluid Science.

[12]  R. Pecnik,et al.  Full-spectrum volumetric solar thermal conversion via graphene/silver hybrid plasmonic nanofluids , 2018, Applied Energy.

[13]  W. Qi,et al.  Size and shape dependent lattice parameters of metallic nanoparticles , 2005 .

[14]  M. Gradeck,et al.  Comparative study of the cooling of a hot temperature surface using sprays and liquid jets , 2014 .

[15]  A. Rashidi,et al.  Effect of dispersion method on thermal conductivity and stability of nanofluid , 2011 .

[16]  A. D. Risi,et al.  Experimental investigation of transparent parabolic trough collector based on gas-phase nanofluid , 2017 .

[17]  Eiyad Abu-Nada,et al.  Numerical Analysis of Al2O3/Water Nanofluids Natural Convection in a Wavy Walled Cavity , 2011 .

[18]  Dennis K. Flaherty,et al.  Evaluation of two instruments for the measurement of aerosols , 1994 .

[19]  Mohamed Gadalla,et al.  Thermo-economic analysis of an integrated solar power generation system using nanofluids , 2017 .

[20]  C. Bae,et al.  Investigations on air-fuel mixing and flame characteristics of biodiesel fuels for diesel engine application , 2017 .

[21]  Ravikanth S. Vajjha,et al.  Application of nanofluids in heating buildings and reducing pollution , 2009 .

[22]  A. Montaser,et al.  Dual-beam, light-scattering interferometry for simultaneous measurements of droplet-size and velocity distributions of aerosols from commonly used nebulizers , 1990 .

[23]  A. Moreira,et al.  A real-time assessment of measurement uncertainty in the experimental characterization of sprays , 2008 .

[24]  W. Finlay,et al.  An in vitro method for determining regional dosages delivered by jet nebulizers. , 1994, Journal of aerosol medicine : the official journal of the International Society for Aerosols in Medicine.

[25]  Nicolas Galanis,et al.  Effect of uncertainties in physical properties on forced convection heat transfer with nanofluids , 2007 .

[26]  Niraj Kumar,et al.  Multi-objective optimization of modified nanofluid fuel blends at different TiO2 nanoparticle concentration in diesel engine: Experimental assessment and modeling , 2019, Applied Energy.

[27]  I. Alarifi,et al.  Thermal and Fluid Dynamics Performance of MWCNT-Water Nanofluid Based on Thermophysical Properties: An Experimental and Theoretical Study , 2020, Scientific Reports.

[28]  C. Medaglia,et al.  Thermofluid Characterization of Nanofluid Spray Cooling Combining Phase Doppler Interferometry with High-Speed Visualization and Time-Resolved IR Thermography , 2020 .

[29]  Xianfan Xu,et al.  Thermal Conductivity of Nanoparticle -Fluid Mixture , 1999 .

[30]  Yan Liu,et al.  Bubble Dynamics and Heat Transfer on Biphilic Surfaces , 2021, Advances in Heat Transfer and Thermal Engineering.