Thermal Conductivity Of Nanofluids Research Articles

A Review on Thermophysical Properties and Nusselt Number Behavior of Al2O3 Nanofluids in Heat Exchangers

During the last several years, the increase in cooling power requirements for heat exchangers have led to an escalation in heat transfer studies being performed on the use of nanofluids as heat transfer fluids. However, limited effort has been attempted to relate and interpret these findings or the anomalies associated with them. The paper compiles test data from several studies conducted on different types of heat exchangers. In this review, a concentrated effort is spent to clarify the ambiguities regarding the effect of nanoparticle size on the nanofluid thermal conductivity and Nusselt number. Results show that the nanofluid thermal conductivity is not influenced by the nanoparticle size, but by the clustering of the particles themselves. The less compact the structure of the nanoparticle clustering is, the greater the enhancement in the nanofluid thermal conductivity is. Data were also compiled to interpret the relation between the nanofluid flow pattern, nanoparticles volume fraction in the base fluid, and the convective heat transfer. The results from the majority of the heat exchanger studies show an increase in the heat transfer coefficient with the increase in nanoparticle volume fraction. However, studies conducted on plate heat exchanges display some inconsistencies. In the majority of the heat exchanger studies with the exception of few, the decrease in the nanoparticle size is shown to result in an enhancement of the bulk fluid Nusselt number. Compiled test data also reveal that the effectiveness of the alumina nanoparticles is dependent on the flow pattern. The increase in the nanoparticles concentration is shown to result in an increase in the nanofluid heat transfer enhancement as the fluid is transitioning from laminar to turbulent flow. In general, the smaller the nanoparticle size is, the greater the enhancement in the fluid Nusselt number is.

A molecular dynamics study of the effect of nanoparticles coating on thermal conductivity of nanofluids

Nanofluids have become the subject of theoretical and experimental researches over the last few decades due to their enhanced heat transfer performance. In this study, thermal conductivity of copper argon nanofluids containing coated and non-coated copper particles is determined through MD simulation. Coating over the nanoparticles is applied to provide long-term stable dispersion and also to enhance the heat transfer performance. Thermal conductivity of nanofluids depends on the types of coating applied over the nanoparticles. The role of surface coating over the nanoparticles in enhancing thermal properties of the nanofluids is discussed and compared to that of non-coated particles. The silver coating is applied over the copper nanoparticles. Green Kubo method is employed to determine the thermal conductivity of the nanofluids. Result shows that, for volume fraction 3% and 86 K system temperature, thermal conductivity enhancement of nanofluid containing coated particle is 17% compared to that of base fluid and without coating, thermal conductivity enhancement is 12%. The mechanism of increased heat transfer performance for surface coating over the nanoparticles is discussed in this paper.

Preparation and characterization of graphene oxide-based nanocomposite materials for solar energy sorption

Two series of nanocomposite materials based on graphene oxide (GO) (Al2O3/GO (Al/GO), Fe3O4/GO (Fe/GO), and Fe3O4–Al2O3/GO (Fe–Al/GO)), and reduced graphene oxide (rGO) (Al2O3/rGO (Al/GO), Fe3O4/rGO (Fe/GO), and Fe3O4–Al2O3/rGO (Fe–Al/rGO)) were prepared and characterized by X-ray and infrared spectra, SEM, TEM and EDX analyses. Graphene oxide was synthesized from graphite by improved Hummers method, then it was reduced by ascorbic acid to obtain rGO. Composite materials were prepared by suspension mixing. GO- and rGO-based materials were dispersed into brine water to form nanofluids. Transmittance spectra and thermal conductivity of nanofluids and reflectance spectra of the three-component composites were systematically investigated to evaluate their thermal sorption capacity. It can be seen from the transmittance spectra that nanofluids capture almost incident light and from the reflectance that synthesized materials absorbed more than 97.5% and 96% of the irradiated solar power. The thermal conductivity results show that hybrid nanofluid showed high thermal conductivity than single nanofluids. The thermal absorption ability of nanofluids was evaluated by change in temperatures and weights of nanofluids. Results showed that all prepared materials (either single form such as GO, rGO, Al2O3 or composite form such as Al/GO, Fe/GO, Fe–Al/GO, Al/rGO, Fe/rGO, Fe–Al/rGO) raised thermal sorption of brine water. The combination of two or three components leaded to higher thermal sorption ability. Fe–Al/GO and Fe–Al/rGO give the highest thermal absorption efficiency (the temperature difference between the blank sample and the sample containing material with content of 0.5 mg mL−1 is 7 °C and 8.5 °C, respectively). Evaporation ability of Fe–Al/GO and Fe–Al/rGO nanofluids increased to 67% and 79%, respectively. The thermal sorption increased with increasing the concentration of materials in nanofluid and lightening intensity (the temperature difference between the blank sample and investigated sample using two lamps was 21 °C). Moreover, 98% of Fe–Al/GO (Fe–Al/rGO) was simply recovered by magnet and the recovered material can be reused with only slight decrease in thermal sorption performance. Prepared nanocomposite was dispersed in brine water (0.15 mg mL−1 in 3.5% NaCl solution) to be distillated using solar energy and the results show that distillation process can be profoundly speeded up.

Direct effect of nanoparticles on the thermal conductivity of CuO-water nanofluid in a phase transition phenomenon using molecular dynamics simulation

The thermal behavior of CuO-water nanofluid is examined on an aluminum surface. The dimensions of simulation boxes are 70 × 70 × 30 A3, 60 × 60 × 30 A3, and 50 × 50 × 30 A3, with the corresponding number of atoms of 104,351, 123,958, and 145,980. Thermal conductivities of fluid and nanofluid are calculated using the Green–Kubo formula. Molecular dynamics simulation results confirm the direct effect of nanoparticles on the values of thermal conductivities of fluid and nanofluid. The value of 0.59 Wm−1 K−1 is obtained for the thermal conductivity of water. But adding three CuO nanoparticles into the water increases this value to 0.85 Wm−1 K−1. The same effect is observed on the thermal behavior of nanofluid upon increasing the size of CuO nanoparticles that raises the value of the thermal conductivity of nanofluid to 0.99 Wm−1 K−1. The heat flux is increased by adding the nanoparticles into the base fluid; thereby, the phase transition (evaporation) occurs in fewer time steps.

Liquid Paraffin Thermal Conductivity with Additives Tungsten Trioxide Nanoparticles: Synthesis and Propose a New Composed Approach of Fuzzy Logic/Artificial Neural Network

A nanofluid (Nf), which contains tungsten trioxide, WO3, nanoparticles as solid-particles distributed in liquid paraffin, is produced. A set-up is provided to experimentally measure the thermal conductivity (TC) of this mixture at various mass fractions and temperatures. Further, two universal approximators of fuzzy logic (FL) and artificial neural network (ANN) are presented to predict the TC of this mixture. The present work’s novelty can be presented as: prepare a WO3/paraffin nanofluid, measure it's TC, and develop a novel statistical/numerical model of FL compared with ANN. As it can be seen, temperature and concentration effects positively on nanofluid TC. Moreover, ANN and fuzzy models show suitable precisions; however, the interpolation capability of the proposed fuzzy model outperforms ANN at non-trained inputs.

Experimental and Theoretical Study on Thermal Conductivity of Kerosene-Based Nanofluids

Thermal conductivity of kerosene-based nanofluids is experimentally studied in the paper. Aluminum (Al), alumina (Al2O3) and titanium dioxide (TiO2) nanoparticles were dispersed respectively in RP3 aviation kerosene, and thermal conductivity of those nanofluids was measured in a wide range of fluid temperature and particle mass fraction. The increase rate of thermal conductivity of kerosene-based nanofluids reached 60% at a temperature of 403K. The thermal conductivity of nanofluids changes with different particles, particle size, particle concentration and temperature etc. The change rules are given in this paper in detail. Meanwhile, a new theoretical model for prediction of thermal conductivity of kerosene-based nanofluids is proposed. The effects of interfacial nanolayer and Brownian motion are considered in the model. And the results of comparison between theoretical model and measurement data are found to be good.

Experimental investigation of convective heat transfer using ethylene glycol-based nano-fluid

Coolant plays important characteristic in automobile industry to prevent failure and damage by balancing the temperature. Due to this approach, coolants are being used as new thermal fluid to study the heat transfer coefficient performance. This study consists of an experimental investigation of internal convective heat transfer of 50:50 Water-Ethylene Glycol based Nano-fluid through a copper tube of 18mm external diameter and 16.5mm internal diameter and a test section of 1m in a fully turbulent regime. Total convective heat transfer coefficient of Nano fluid at three different volumetric concentrations of nanoparticles is estimated. Local convective heat transfer at eight different points along the tube at varying Reynolds number is also determined. At 0.15% volumetric concentration of SiO2 Nanoparticles (NPS) 29% increment in convective heat transfer coefficient (CHT) is observed. The decrease in the heat transfer rate is observed with changing distance axially. Particles disorganized movement of NPs and undulation in the fluid and increased in thermal conductivity of Nano fluid can be possible reason for extra ordinary change in heat transfer.

Second Law Analysis of Magneto Radiative GO-MoS2/H2O–(CH2OH)2 Hybrid Nanofluid

Entropy Generation Optimization (EGO) attained huge interest of scientists and researchers due to its numerous applications comprised in mechanical engineering, air conditioners, heat engines, thermal machines, heat exchange, refrigerators, heat pumps and substance mixing etc. Therefore, the study of radiative hybrid nanofluid (GO-MoS2/C2H6O2–H2O) and the conventional nanofluid (MoS2/C2H6O2–H2O) is conducted in the presence of Lorentz forces. The flow configuration is modeled between the parallel rotating plates in which the lower plate is permeable. The models which govern the flow in rotating system are solved numerically over the domain of interest and furnished the results for the temperature, entropy generation and thermophysical characteristics of the hybrid as well as conventional nanofluids, respectively. It is examined that the thermal profile intensifies against stronger thermal radiations and magnetic field. The surface of the plate is heated due to the imposed thermal radiations and magnetic field which cause the increment in the temperature. It is also observed that the temperature declines against more rotating plates. Further, the entropy production increases for more dissipative effects and declines against more magnetized fluid. Thermal conductivities of the hybrid nanofluid enhances promptly in comparison with regular liquid therefore, under consideration hybrid nanofluid is reliable for the heat transfer. Moreover, dominating thermal transport is perceived for the hybrid nanofluid which showed that hybrid suspension GO-MoS2/C2H6O2–H2O is better for industrial, engineering and technological uses.

A review of passive methods in microchannel heat sink application through advanced geometric structure and nanofluids: Current advancements and challenges

AbstractMicrochannel heat sink (MCHS) is an advanced cooling technique to fulfil the cooling demand for electronic devices installed with high-power integrated circuit packages (microchips). Various microchannel designs have been innovated to improve the heat transfer performance in an MCHS. Specifically, the utilisation of nanotechnology in the form of nanofluid in an MCHS attracted the attention of researchers because of considerable enhancement of thermal conductivity in nanofluid even at a low nanoparticle concentration. However, a high-pressure drop was the main limitation as it controls the MCHS performance resulted from heat transfer augmentation. Therefore, this study aimed to critically summarise the challenges and limitations of both single and hybrid passive methods of MCHS. Furthermore, the performance of nanofluid as a coolant in the MCHS as affected by the type and concentration of nanoparticle and the type of base fluid was reviewed systematically. The review indicated that the hybrid MCHS provides a better cooling performance than MCHS with the single passive method as the former results in a higher heat transfer rate with minimal pressure drop penalty. Besides that, further heat transfer performance can be enhanced by dispersing aluminium dioxide (Al2O3) nanoparticles with a concentration of less than 2.0% (v/v) in the water-based coolant.

Optimization and modeling of thermal conductivity and viscosity of Cu/engine oil nanofluids by NSGA‐II using RSM

This study provides the optimization of the thermophysical properties of Cu/engine oil nanofluid. In this optimization, the objective functions were determined using response surface methodology (RSM) to analyze the experimental data of nanofluid viscosity and thermal conductivity (TC). Two equations are presented for the accurate prediction of TC and viscosity data. The nondominated sorting genetic algorithm II (NSGA‐II) method was used for multi‐objective optimization (Mo‐O), and Pareto's front was introduced to study optimal viscosity and TC. According to the results, the highest TC and the lowest viscosity occur when the temperature and solid volume fraction of the nanofluid are at their maximum values.

Thermal performance of U‐shaped serpentine microchannel heat sink using various metal oxide nanofluids

AbstractThis study aims to evaluate the thermal performance and friction factor characteristics of the U‐shaped serpentine microchannel heat sink using three different nanofluids. Two distinct nanoparticles, namely Al2O3 (alumina) and CuO (copper oxide), were used for the preparation of nanofluids using water and ethylene glycol (EG) as base fluids. Three nanofluids, namely nanofluid I (Al2O3 + water), nanofluid II (CuO + water), and nanofluid III (CuO + EG), have been prepared. The results showed that the thermal conductivity of nanofluids was increased for all concentrations (from 0.01 to 0.3%), compared with base fluids. The theoretical values derived from the relationship between the Darcy friction factor showed a clear understanding of the fully developed laminar flow. Thermal resistance for nanofluid III was lower than other nanofluids, resulting in a higher cooling efficiency. The nanofluid mechanism and the geometry of the U‐shaped serpentine heat sink have led to the improvement in the thermal performance of electronic cooling systems.

Comprehensive Experimental Study on the Thermophysical Characteristics of DI Water Based Co0.5Zn0.5Fe2O4 Nanofluid for Solar Thermal Harvesting

The thermophysical properties of water-based Co0.5Zn0.5Fe2O4 magnetic nanofluid were investigated experimentally. Consequently, the viscosities of 0.25 wt% and 1 wt% Co0.5Zn0.5Fe2O4 nanofluid were 1.03 mPa∙s and 1.13 mPa∙s, each greater than that of the 20 °C base fluid (water), which were increased by 7.3% and 17.7%, respectively. The Co0.5Zn0.5Fe2O4 nanofluid thermal conductivity enhanced from 0.605 and 0.618 to 0.654 and 0.693 W/m·°C at concentrations of 0.25 wt% and 1 wt%, respectively, when the temperature increased from 20 to 50 °C. The maximum thermal conductivity of the Co0.5Zn0.5Fe2O4 nanofluid was 0.693 W/m·°C at a concentration of 1 wt% and a temperature of 50 °C. Furthermore, following a solar exposure of 120 min, the photothermal energy conversion efficiency of 0.25 wt%, 0.5 wt%, 0.75 wt%, and 1 wt% Co0.5Zn0.5Fe2O4 nanofluids increased by 4.8%, 5.6%, 7.1%, and 4.1%, respectively, more than that of water.

Thermal Conductivity and Stability of Hydrocarbon-Based Nanofluids with Palladium Nanoparticles Dispersed by Modified Hyperbranched Polyglycerol.

Palladium nanoparticles, which were prepared by modified hyperbranched polyglycerol (mHPG) as stabilizers, can be dispersed well in nonpolar organic solvents and form highly stable nanofluids. The influences of three mHPG products modified with cyclohexanethiol (CSHPG), dodecanethiol (DSHPG), and octadecanethiol (OSHPG) on the preparation and stability of the palladium nanoparticles were investigated. The stability and thermal conductivity enhancement of the hydrocarbon-based nanofluids with Pd@mHPG (Pd@CSHPG, Pd@DSHPG, and Pd@OSHPG) compared to the corresponding base fluid were investigated at different temperatures. The average diameters of nanoparticles stabilized by CSHPG, DSHPG, and OSHPG are within 2.7–3.6 nm. The palladium nanoparticles could be dispersed well in the nonpolar base fluid such as decalin. The nanofluids with Pd@DSHPG and Pd@OSHPG could remain stable for up to 330 days at room temperature. The nanofluid with Pd@DSHPG or Pd@OSHPG could be stable for more than 24 h at 110 °C. The thermal conductivity of the nanofluids improved with increasing temperature and the mass fraction of nanoparticles compared to the corresponding base fluid. The long alkyl chain-modified HPG can give better protection for nanoparticles from agglomeration and assist metal nanoparticles in enhancing the thermal conductivity of nanofluids.

Molecular dynamics simulation of the thermal properties of the Cu-water nanofluid on a roughed Platinum surface: Simulation of phase transition in nanofluids

Barrier size influences on the thermal behavior of Ar/Cu nanofluid are reported in this simulation work. Molecular dynamics method is implemented with a large molecular/atomic parallel simulator. Furthermore, Ar/Cu nanofluid is simulated with Universal Force Field (UFF) and Embedded Atom Model (EAM) force fields and these force fields are appropriate to our thermal study. For the thermal behavior of this nanofluid, we record the physical parameters like total energy, thermal conductivity of nanofluid, density, the number of nanofluid atoms in the gas phase, and atomic temperature. Simulation results show that atomic structures have thermal stability with −318 eV value for total energy parameter. Physically, the atomic barrier causes the atomic phase transition phenomena to happen in a shorter time. Numerically, this parameter varies from 0.61 ns to 0.55 ns when the Platinum (Pt) barriers height increases from 5 Å to 10 Å. We calculated that the maximum density of nanofluid atoms reaches to 0.00025 Atom/Å3 by atomic barriers enlarging. So, we conclude that, by increasing the received heat flux with Ar/Cu nanofluid, the thermal conductivity converged in shorter simulation time. Numerically, the thermal conductivity of simulated structures converges to 0.016400 W/m.K after 0.63 ns.

Non-magnetized mixed convective viscous flow submerged in titanium oxide and aluminum titanium oxide hybrid nanoparticles towards a surface of cylinder

Hybrid nanofluids are novel fluids created by suspending two or more dissimilar nano sized particles in base fluids. Thermal conductivity of hybrid nanofluids is more than nanofluids. Now a day, due to high thermal conductivity and applications in engineering and industry, hybrid nanofluids have become attractive area of research for scientist and researchers. The main objective of current communication is to study the stagnation point flow and heat transfer in viscous hybrid nanofluid towards a stretched cylinder. Flow characteristics are examined under the effect of magnetic field and mixed convention. Furthermore, energy communication is constructed considering thermal radiation, uniform heat source and viscous dissipation. The obtained governing dimensional model is transformed into ordinary ones using suitable transformations. ND-solve code is used to tackle the ordinary differential equations. Results are discussed and compared subject to nanofluid and hybrid nanofluid and plotted graphically. Moreover, Nusselt number and skin friction coefficient are studied numerically. Key outcomes are highlighted at the end.

Modelling Thermal Conduction in Nanoparticle Aggregates in the Presence of Surfactants.

Many theoretical and experimental studies have shown that the addition of nanoparticles into conventional fluids may generate nanofluids with significantly improved heat transfer properties. In the present work, the effect of nanoparticle aggregation on the thermal conductivity of nanofluids is studied, considering also the effect of surfactants that are typically added to stabilise the nanofluid. A method for simulating aggregate formation is developed here that allows tailoring of the fractal dimension and the number density of the nanoparticles to desired values. The method is shown to be computationally simple and fast. Data that are extracted from electron microscope images are compared with simulation results regarding surface porosity and the autocorrelation function. The surfactants are modelled as a layer around the particles, and the effective thermal conductivity is calculated with a meshless numerical technique. Significant increase in conductivity is observed for small values of the fractal dimension and for large number density of particles in the aggregate. The simulations are in good agreement with experimental results. It is also concluded that prediction of the conductivity of such nanofluids requires the knowledge of the type and the amount of the surfactant added.

Numerical simulation of nanoparticles size/aspect ratio effect on thermal conductivity of nanofluids using lattice Boltzmann method

Recent developments in nanofluids have led to a renewed interest in the geometrical effects of nanoparticles on the effective thermal conductivity (ETC) of nanofluids. Although the experimental data for the effect of nanoparticles shapes (the aspect ratio) on ETC are quite consistent, there are still controversial results regarding the effect of the nanoparticles size. Theoretical approaches have been proposed to shed light on the experimental observations in both macroscopic and microscopic scales. However, these approaches cannot be generalized due to the collective interrelated behaviours of nanoparticles. In this paper, a mesoscale numerical simulation, Lattice Boltzmann method (LBM), is implemented to study the effect of nanoparticle geometry on the nanofluids thermal conductivity. The results demonstrate that the nanofluids thermal conductivity and the nanoparticles volume fraction can be linearly correlated. In essence, increasing the nanoparticles aspect ratio can improve ETC of nanofluids. However, the nanoparticle size is not statistically significant (P-value>0.05) to be considered as an influencing parameter (as observed in the controversial results of the experiments) when the interfacial phenomena are not taken into account. The surface to volume ratio of the particle is the parameter that should be studied as all the solid/liquid interfacial interactions depends on this ratio.

Comparative evaluation on the thermal properties and stability of MWCNT nanofluid with conventional surfactants and ionic liquid

Conventional surfactants such as CTAB (cetrimonium bromide), SDS (sodium dodecyl sulphate), SDBS (sodium dodecyl sulphonate) are combined with nanofluids to improve the stability and thermal conductivity of nanofluids. These nanofluids are mainly used for heat transfer applications where heating and cooling are usual courses of action which result in surfactants producing foams and polluting the heat transfer media, affecting the total system performance. Besides, the common surfactant molecules that augment the thermal resistance between the nanoparticles and base fluid also affect the thermophysical properties of the nanofluid. In this paper, [Bmim][Cl] (1-butyl-3-methylimidazolium chloride), a high purity ionic liquid (IL) with higher thermal stability was used to provide a comparative study on the stability and thermal properties with that of the conventional surfactants (CTAB, SDS, SDBS) on multiwalled carbon nanotubes (MWCNT)/propylene glycol (PG) nanofluid. The transient hot-wire based KD2-Pro and zeta potential results demonstrated that the inclusion of ionic liquid improved the thermal conductivity and stability of the formulated nanofluid. However, much like the conventional surfactants, the strong electrostatic repulsive force created by the ionic liquid was found to decrease when the temperature is increased. The outcome demonstrated the most extreme thermal conductivity upgrade of 33.7% at 303 K and maximum dispersion stability of more than one month without any aggregation for the nanofluid containing ionic liquid.

Improving the thermo-physical and rheological properties of crude oil (CO) by the synthesized CuO/SiO2/CaP nanocomposite for drag reduction through horizontal pipelines

The thermo-physical properties and rheological behavior of crude oil (CO) have substantial efficacies on transportation, processing, and refinery operation. SiO2 (silica)–CaP (calcium phosphate)–CuO (copper oxide) nanocomposite was synthesized by the sono-co-precipitation technique. In this work, the impact of nanocomposite volume fraction as well as temperature on the thermo-physical and also rheological characteristics of SiO2–CaP–CuO-based CO nanofluid were evaluated. All experimental tests were done in the temperatures and nanocomposite concentrations of 25–55 °C and 0.05–0.75 vol.%, respectively. Also, the drag reduction of the nanofluid in horizontal pipelines was elucidated by the SiO2–CaP–CuO-based CO nanofluid at 25 °C. The highest dynamic viscosity enhancement was found to be about 44.57% for 0.75 vol.% nanocomposite particles. The nanofluids thermal conductivity augmented with nanocomposite volume fraction increment. The greatest increment in nanofluids thermal conductivity was obtained about 17.26% at 0.75 vol.%. Moreover, four correlations were expanded for the dynamic viscosity and thermo-physical characteristics of the nanofluids with relative average deviation (RAD) percentage of less than 1%, which depended on temperature and nanocomposite volume concentration. The empirical relationships indicated a satisfactory compliance with the laboratory data. Additionally, outcomes demonstrated that the drag reduction of hybrid nanofluid in the horizontal pipeline under fully turbulent flow increased with enhancing the nanofluid concentration. Drag reduction of the nanofluids in the rough pipelines was higher than that in the smooth pipeline at the same Reynolds number in the range of 6500–42,000 and different pipe’s diameter (0.5–1 in.). No considerable increase and/or a reduction in hybrid nanofluid thermal conductivity was found for the recovered nanocomposite in various volume concentrations. The highest dynamic viscosity reduction after three times recovery treatment was obtained about 0.7% for 0.5 vol.% nanocomposite particles.

An Experimental Investigation on Thermal Conductivity and Viscosity of Graphene doped CNTs /TiO2 Nanofluid

This paper presents the findings of the stability, thermal conductivity and viscosity of CNTs (doped with 10 wt% graphene)- TiO2 hybrid nanofluids under various concentrations. While the usage of cutting fluid in machining operation is necessary for removing the heat generated at the cutting zone, the excessive use of it could lead to environmental and health issue to the operators. Therefore, the minimum quantity lubrication (MQL) to replace the conventional flooding was introduced. The MQL method minimises the usage of cutting fluid as a step to achieve a cleaner environment and sustainable machining. However, the low thermal conductivity of the base fluid in the MQL system caused the insufficient removal of heat generated in the cutting zone. Addition of nanoparticles to the base fluid was then introduced to enhance the performance of cutting fluids. The ethylene glycol used as the base fluid, titanium dioxide (TiO2) and carbon nanotubes (CNTs) nanoparticle mixed to produce nanofluids with concentrations of 0.02 to 0.1 wt.% with an interval of 0.02 wt%. The mixing ratio of TiO2: CNTs was 90:10 and ratio of SDBS (surfactant): CNTs was 10:1. The stability of nanofluid checked using observation method and zeta potential analysis. The thermal conductivity and viscosity of suspension were measured at a temperature range between 30˚C to 70˚C (with increment of 10˚C) to determine the relationship between concentration and temperature on nanofluid’s thermal physical properties. Based on the results obtained, zeta potential value for nanofluid range from -50 to -70 mV indicates a good stability of the suspension. Thermal conductivity of nanofluid increases as an increase of temperature and enhancement ratio is within the range of 1.51 to 4.53 compared to the base fluid. Meanwhile, the viscosity of nanofluid shows decrements with an increase of the temperature remarks significant advantage in pumping power. The developed nanofluid in this study found to be stable with enhanced thermal conductivity and decrease in viscosity, which at once make it possible to be use as nanolubricant in machining operation.