This study experimentally investigates the thermal performance of graphene–water nanofluids for spray cooling applications under high-heat-flux conditions. Five nanoparticle volume concentrations (0.01%–0.2%) were systematically analyzed to determine the optimal formulation for enhanced heat transfer. Experiments were conducted on a square copper substrate (10 mm2) using a full-cone pressure-swirl nozzle (0.4 mm orifice diameter) at volumetric fluxes ranging from 0.83 to 2.5 cm3 cm−2 s−1. The results reveal a pronounced dependence of cooling performance on nanoparticle concentration, with a peak enhancement observed at 0.1 vol% graphene loading. At this optimal condition, the nanofluid achieved a 43% increase in average heat transfer coefficient, reaching 4.5 W cm−2 K−1, and a 66% improvement in critical heat flux (CHF), attaining 450 W cm−2 compared with pure water. Further increases in concentration beyond 0.1 vol% led to marginal performance degradation due to nanoparticle agglomeration and partial surface fouling. The findings confirm that graphene nanofluids, owing to their superior thermal conductivity, high surface area, and colloidal stability, represent a promising class of next-generation coolants for spray-based thermal management systems in electronics, aerospace, and renewable energy applications.
Bar-CohenAIyengarM. Design and optimization of air-cooled heat sinks for sustainable development. Tech2002; 25: 584–591.
2.
MudawarI. Assessment of high-heat-flux thermal management schemes. IEEE Trans Compon Packag Technol2001; 24: 122–141.
3.
KandlikarSG. High flux heat removal with microchannels—A roadmap of challenges and opportunities. Heat Transf Eng2005; 26: 5–14.
4.
KandlikarSGGrandeWJ. Evolution of microchannel flow passages-thermohydraulic performance and fabrication technology. Heat Transf Eng2003; 24: 3–17.
5.
AgostiniBFabbriMParkJE, et al.State of the art of high heat flux cooling technologies. Heat Transf Eng2007; 28: 258–281.
6.
EbadianMALinCX. A review of high-heat-flux heat removal technologies. J Heat Tran2011; 133: 110801.
7.
SilkEAGolliherELPaneer SelvamR. Spray cooling heat transfer: technology overview and assessment of future challenges for micro-gravity application. Energy Convers Manag2008; 49: 453–468.
8.
LiangGMudawarI. Review of spray cooling – part 1: single-phase and nucleate boiling regimes, and critical heat flux. Int J Heat Mass Tran2017; 115: 1174–1205.
9.
SawanMECarbonMW. A review of spray-cooling and bottom-flooding work for lwr cores. Nucl Eng Des1975; 32: 191–207.
10.
JhaJMRavikumarSVHaldarK, et al.Heat transfer from a hot moving steel plate by air-atomized spray impingement. Exp Heat Transf2015; 29: 78–96.
11.
SurRSunKJeffriesJB, et al.TDLAS-based sensors for in situ measurement of syngas composition in a pressurized, oxygen-blown, entrained flow coal gasifier. Appl Phys B2014; 116: 33–42.
12.
SinghSKukrejaR. Experimental investigations on heat transfer enhancement of enhanced surfaces in spray cooling using HFE-649. Int J Multiphas Flow2023; 161: 104387.
13.
KimJ. Spray cooling heat transfer: the state of the art. Int. Heat Fluid Flow2007; 28: 753–767.
14.
SinghSKukrejaR. Experimental study on effects of surfactant and spray inclination on heat transfer performance in nonboiling regime. Energy Sources, Part A Recover. Util. Environ. Eff2021; 47: 2007313–2007315.
15.
ChoiSUSEastmanJA. Enhancing thermal conductivity of fluids with nanoparticles. ASME Int. Mech. Eng. Congr. Expo1995; 7: 99–105.
16.
RajaMVijayanRDineshkumarP, et al.Review on nanofluids characterization, heat transfer characteristics and applications. Renew Sustain Energy Rev2016; 64: 163–173.
17.
NematiHMoradaghayMMoghimiMA, et al.Natural convection heat transfer over horizontal annular elliptical finned tubes. Int Commun Heat Mass Tran2020; 118: 104823.
18.
DhaidanNSAl-MousawiFN. Thermal-hydraulic features of the turbulent flow through ribbed channels. J Appl Mech Tech Phys2022; 63: 634–642.
19.
WangJXLiYZMaoYF, et al.Comparative study of the heating surface impact on porous-material-involved spray system for electronic cooling – an experimental approach. Appl Therm Eng2018; 135: 537–548.
20.
WenDDingY. Experimental investigation into convective heat transfer of nanofluids at the entrance region under laminar flow conditions. Int J Heat Mass Tran2004; 47: 5181–5188.
21.
KeblinskiPPhillpotSRChoiSUS, et al.Mechanisms of heat flow in suspensions of nano-sized particles (nanofluids). Int J Heat Mass Tran2002; 45: 855–863.
22.
IjamASaidurR. Nano fluid as a coolant for electronic devices (cooling of electronic devices). Appl Therm Eng2012; 32: 76–82.
23.
DasSKChoiSUSPatelHE. Heat transfer in Nanofluids—A review. Heat Transf Eng2007; 27: 3–19.
24.
HsiehSSLiuHHYehYF. Nanofluids spray heat transfer enhancement. Int J Heat Mass Tran2015; 94: 104–118.
25.
Hemmat EsfeMHosseini TamrabadSNTavallaeeR, et al.Comprehensive and statistical analysis of dynamic viscosity of water-based nanofluids (2005–2023): review of publication trends, leading publications, prominent researchers and active countries in this field. J Therm Anal Calorim2025; 150: 9723–9741.
26.
MalýMMoitaASJedelskyJ, et al.Effect of nanoparticles concentration on the characteristics of nanofluid sprays for cooling applications. J Therm Anal Calorim2019; 135: 3375–3386.
27.
WangBLiuZZhangB, et al.Effect of nanoparticle type and surfactant on heat transfer enhancement in spray cooling. J Therm Sci2020; 29: 708–717.
28.
Karimi BakhtiyarNEsmaeiliSJavadpourR, et al.Experimental investigation of indirect heat transfer through a novel designed lab-scale setup using functionalized MWCNTs nanofluids (MWCNTs-COOH/water and MWCNTs- OH/water). Case Stud Therm Eng2023; 45: 102951.
29.
MohammadfamYZeinali HerisS. Thermophysical characteristics and forced convective heat transfer of ternary doped magnetic nanofluids in a circular tube: an experimental study. Case Stud Therm Eng2023; 52: 103748.
30.
KhouriOGoshayeshiHRMousaviSB, et al.Heat transfer enhancement in industrial heat exchangers using graphene oxide nanofluids. ACS Omega2024; 9: 24025–24038.
31.
Nakhaee SharifMGoshayeshiHSalehR, et al.Experimental study on the efficiency improvement of a forced draft wet cooling tower via magnetic Fe3O4 nanofluid and optimized packing. Case Stud Therm Eng2025; 74: 106904.
32.
SinghSKukrejaR. Experimental study on spray cooling heat transfer enhancement using MWCNT and TiO2 hybrid nanofluid. Proc Inst Mech Eng Part E J Process Mech Eng2022; 238: 78–90.
33.
ChakrabortySKumarPChaurasiaCK, et al.Spray cooling investigation of very-hot aisi 304 steel plate with Mono and mixed Sio2, cuo nanofluid. SSRN Journal2022; 10: 4159406.
34.
BharadwajGSharmaKPandeyAK, et al.Thermal conductivity augmentation of reduced graphene oxide-based nanofluids and its solar application. MRS Adv2024; 9: 1004–1010.
35.
GhoshSCalizoITeweldebrhanD, et al.Extremely high thermal conductivity of graphene: prospects for thermal management applications in nanoelectronic circuits. Appl Phys Lett2008; 92: 151911.
36.
YuWFranceDMRoutbortJL, et al.Review and comparison of nanofluid thermal conductivity and heat transfer enhancements. Heat Transf Eng2008; 29: 432–460.
37.
ZolfalizadehMHerisSZPourpashaH, et al.Experimental investigation of the effect of Graphene/water nanofluid on the heat transfer of a shell-and-tube heat exchanger. Int J Energy Res2023; 2023: 3477673.
38.
ShaikAHChakrabortySSaboorS, et al.Cu-Graphene water-based hybrid nanofluids: synthesis, stability, thermophysical characterization, and figure of merit analysis. J Therm Anal Calorim2024; 149: 2953–2968.
39.
SandhyaMRamasamyDSudhakarK, et al.A systematic review on graphene-based nanofluids application in renewable energy systems: preparation, characterization, and thermophysical properties. Sustain Energy Technol Assessments2021; 44: 101058.
PakBCChoYI. Hydrodynamic and heat transfer study of dispersed fluids with submicron metallic oxide particles. Exp Heat Transf2007; 11: 151–170.
42.
BatchelorGK. The effect of Brownian motion on the bulk stress in a suspension of spherical particles. J Fluid Mech1977; 83: 97–117.
43.
MaxwellJC. A treatise on electricity and magnetism. 2nd ed.Oxford, UK: Clarendon Press, 1881, p. 435.
44.
HsiehSFanTTsaiH. Spray cooling characteristics of water and R-134a. Part I: nucleate boiling. Int J Heat Mass Tran2004; 47: 5703–5712.
45.
HouYLiuXLiuJ, et al.Experimental study on phase change spray cooling. Exp Therm Fluid Sci2013; 46: 84–88.
46.
RiniDPChenRHChowLC. Bubble behavior and nucleate boiling heat transfer in saturated FC-72 spray cooling. J Heat Tran2002; 124: 63–72.
47.
AnSKimDYLeeJG, et al.Supersonically sprayed reduced graphene oxide film to enhance critical heat flux in pool boiling. Int J Heat Mass Tran2016; 98: 124–130.
48.
SarafrazMMSafaeiMRTianZ, et al.Thermal assessment of nano-particulate graphene-Water/Ethylene glycol (WEG 60:40) nano-suspension in a compact heat exchanger. Energies2019; 12: 1929.
49.
SinghSKSharmaD. Pool boiling experiments in graphene, graphene oxide and reduced graphene oxide nanofluid. Heat Transf Eng2025; 74: 1–20.
50.
MurshedSMSLeongKCYangC. Enhanced thermal conductivity of TiO2 - water based nanofluids. Int J Therm Sci2005; 44: 367–373.
51.
DasSKPutraNThiesenP, et al.Temperature dependence of thermal conductivity enhancement for nanofluids. J Heat Tran2003; 125: 567–574.
52.
SinghSKukrejaR. Effect of binary mixed-surfactants and hybrid nanofluid on spray cooling heat transfer. Proc Inst Mech Eng Part E J Process Mech Eng2022; 238: 112–123.
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