Multi-walled Carbon Nanotube Nanofluids Research Articles

Performance of Functionalized MWCNT–Water Nanofluids for Heat Transfer Applications

The higher level of performance, compactness and integration of modern electronic components often results in heat dissipation issues. Hence, there is an increasing interest in multiwalled carbon nanotubes (MWCNTs) due to their very attractive thermal properties. In this study, functionalized MWCNT (F-MWCNT) and different types of surfactants—Arabic gum (AG), dodecylbenzenesulphonic acid (DBSA) and Chinese ink (CI)—are incorporated into water-based nanofluids to improve the stability and dispersion behavior of the nanofluids. A two-step approach was used to prepare the nanofluids, and 0.5 vol% of F-MWCNT was used in the nanofluids formulation. Nanofluids prepared using 0.5 vol% of F-MWCNT with DBSA surfactant exhibited the highest thermal conductivity enhancement of 48% compared to other nanofluids. The results are supported by stability tests using visual observation and zeta potential. Notably, the F-MWCNT nanofluids with AG and DBSA exhibited an improvement in stability compared to those MWCNT and F-MWCNT nanofluids without surfactant. On the other hand, the experimental work on the closed-loop electronic cooling system revealed that nanofluids prepared with 0.5 vol% of F-MWCNT without surfactants exhibited better performance than F-MWCNT nanofluids with surfactants. This indicates that 0.5 vol% of F-MWCNT is sufficient for use as a nanofluid for a closed-loop electronic cooling system without the addition of surfactant.

Influence of solvents on the enhancement of thermophysical properties and stability of multi-walled carbon nanotubes nanofluid

Multi-walled carbon nanotubes (MWCNTs) are a contemporary class of nanoparticles that have a prominent thermal, electrical and mechanical properties. There have been numerous studies on the enhancement of thermophysical properties of nanofluids. However, there is only limited research on thermal and stability analysis of MWCNT nanofluids with various kinds of solvents or base fluids, namely propylene glycol, ethanol, ethylene glycol, polyethylene glycol, methanol and water. This paper reports the enhancement of thermophysical properties and stability of MWCNTs with six different base fluids in the presence of sodium dodecyl benzene sulfonate surfactant with a mass concentration of 0.5 wt%. Thermal and dispersion stabilities were determined using a thermogravimetric analyzer (TGA) and Zeta potential, along with a visual inspection method to evaluate the agglomeration or sedimentation of MWCNT nanoparticles over a period of one month. Ultraviolet–visible spectroscopy and Fourier transform infrared spectroscopy were utilized to identify the molecular components and light absorption of the formulated nanofluids at their maximum wavenumber (4500 cm−1) and wavelength (800 nm). In addition, thermophysical properties such as thermal conductivity, specific heat capacity, viscosity and density with a peak temperature of 200 °C were also experimentally evaluated. The TGA results illustrated that MWCNT/ethylene glycol nanofluid achieved maximum thermal stability at 140 °C and it revealed a maximum zeta potential value of −61.8 mV. Thus, ethylene glycol solution was found to be the best base liquid to homogenize with MWCNTs for acquiring an enhanced thermophysical property and a long-term stability.

Heat transfer and friction factor analysis of MWCNT nanofluids in double helically coiled tube heat exchanger

The convective heat transfer rate and friction factor analysis are determined with the help of a double helically coiled tube heat exchanger by handling multiwall carbon nanotube (MWCNT)/water-based nanofluids as a cooling medium. This experiment was conducted with constant heat flux method and a laminar flow regime in the range of 120–180 L h−1. The 0.2–0.6% volume concentration of MWCNT/water-based nanofluids was prepared by using two-step methods. It is conceived that the MWCNT/water-based nanofluids had produced a higher convective heat transfer compared with water. It is also perceived that heat transfer increases with an increasing volume concentration of MWCNT/water-based nanofluids. Finally, the highest convective heat transfer 35% was recorded at a 0.6% volume concentration of MWCNT/water-based nanofluids at 140 L h−1 flow rate and at 1400 Dean number. It is drawn that the friction factor using MWCNT nanofluids is 40% greater than water with Dean number range 1400–2400.

An experimental investigation on natural convection of non-covalently functionalized MWCNTs nanofluids: Effects of aspect ratio and inclination angle

Abstract An experimental analysis was conducted to study natural convection heat transfer of water-based nanofluids. Two enclosures with the length × width × height(cm) dimensions of 10 × 10 × 10 and 20 × 10 × 10 and the inclination slopes of 0, 45 and 90° were considered. One of the walls was cooled and the opposite wall was heated. Multi-walled carbon nanotube (MWCNT)/water nanofluids were used as the heat transfer fluid while the MWCNTs were non-covalently functionalized by gum Arabic (GA). The MWCNT-GA/water nanofluids were prepared using 0.005, 0.05 and 0.1 wt% nanoparticles. According to the results, adding MWCNTs to water reduced free convection heat transfer in both enclosures. The effect of increasing MWCNT concentration on Nusselt number was found to be greater than the impact of changing Rayleigh number. Furthermore, free convection heat transfer increased with reducing inclination angle from 90° to 0° at high Rayleigh numbers. It was noticed that changing inclination angle has no considerable influence on Nusselt number at lower Rayleigh numbers. Moreover, free convection heat transfer increased about 8.77% with increasing the aspect ratio from 1 to 2. The highest reduction of Nusselt number was attributed to a system with the aspect ratio, concentration and inclination angle of 1, 0.1 wt% and 90°, respectively.

Clean manufacturing of Ti-6Al-4V under CO2-snow and hybrid nanofluids

During the machining of α+β intermetallic stable titanium alloy, their poor thermal conductivity and resistance at elevated temperature accumulates most of the shearing and friction heat. The resulting heat damage the cutting tool, causes in high power consumption, shorter tool life and poor surface quality. Therefore, it is important to choose a latest cooling technique with excellent capacity to remove heat, chips and frictional effects from the cutting zone. Therefore, Carbon dioxide snow (CO2-snow) and hybrid copper oxide (CuO)-multi-walled carbon nanotubes (MWCNTs) nanofluids based minimum quantity lubrication (MQL) are compared to achieve clean cooling/lubrication technique to machine biomedical/aerospace material Ti-6Al-4V. Taguchi L9 orthogonal array was applied to design the experiments. Critical machining parameters are cutting speed (m/min), feed (mm/rev), and cooling mode. The output responses are surface quality Ra (μm), cutting power Pc (W), cutting temperature T (oC), and tool life TL (min) were evaluated under CO2-snow and MQL-hybrid nanofluids. Findings have revealed less surface roughness and longer tool life under hybrid nanofluids. While CO2-snow has justified less temperature and power consumption at high cutting conditions.

On evaluation of thermophysical properties of transformer oil-based nanofluids: A comprehensive modeling and experimental study

Transformer oil-based nanofluids are known to have higher thermal conductivity and heat transfer performance compared to conventional transformer oils. In this study, four different types of transformer oil-based nanofluids are synthesized using the well-known two-step method. The first nanofluid contains pure multi-walled carbon nanotubes (MWCNTs), while other samples consist of 20 Vol% of MWCNTs and 80 Vol% of different oxide nanoparticles (i.e., Al2O3, TiO2, and SiO2). The dynamic viscosity and thermal conductivity of prepared samples are investigated in seven different volume fractions of 0.001, 0.0025, 0.005, 0.01, 0.025, 0.05, and 0.1%. Besides, the breakdown voltage of the pure transformer oil and nanofluids containing 0.05 and 0.1 Vol% of nanoparticles is investigated. The outcomes show that dielectric properties of hybrid carbon-based nanofluids are far better compared to those properties of the pure MWCNTs nanofluids. Finally, eight different soft computing approaches, including group method of data handling (GMDH), support vector machine (SVM), radial basis function (RBF) neural network, multilayer perceptron (MLP), and MLP and RBF models optimized with bat and grasshopper optimization algorithm (GOA), are used to model the viscosity and thermal conductivity of synthesized nanofluids. The outcomes show that the GMDH approach significantly outperforms all other models in terms of predicting the thermal conductivity and dynamic viscosity of transformer oil-based nanofluids.

Comparison between Nucleate Pool Boiling Heat Transfer of Graphene Nanoplatelet- and Carbon Nanotube- Based Aqueous Nanofluids.

An increase of nucleate pool boiling with the use of different fluid properties has received much attention. In particular, the presence of nanostructures in fluids to enhance boiling was given special consideration. This study compares the effects of graphene nanoplatelet (GNP), functionalized GNP with polyethylene glycol (PEG), and multiwalled carbon nanotube (CNT) nanofluids on the pool boiling heat transfer coefficient and the critical heat flux (CHF). Our findings showed that at the same concentration, CHF for functionalized GNP with PEG (GNP–PEG)/deionized water (DW) nanofluids was higher in comparison with GNP- and CNT-based nanofluids. The CHF of the GNP/DW nanofluids was also higher than that of CNT/DW nanofluids. The CHF of GNP–PEG was 72% greater than that of DW at the concentration of 0.1 wt %. There is good agreement between measured critical heat fluxes and the Kandlikar correlation. In addition, the current results proved that the GNP–PEG/DW nanofluids are highly stable over 3 months at a concentration of 0.1 wt %.

Comparison Study on Photo-Thermal Energy Conversion Performance of Functionalized and Non-Functionalized MWCNT Nanofluid

Multiwalled carbon nanotubes (MWCNTs) have attracted attention from researchers because of their superior thermal properties and high optical absorption. In this investigation, the thermal and optical properties of functionalized and nonfunctionalized MWCNT nanofluid based on ethylene glycol/water were experimentally studied and compared. The results indicated that the use of the functionalized MWCNT nanofluid improved the thermal properties and optical absorption performance compared with the nonfunctionalized MWCNT nanofluid. The thermal conductivity enhancement of the functionalized MWCNT nanofluid was higher than that of the nonfunctionalized MWCNT nanofluid. The maximum thermal conductivity enhancement (10.15%) was observed in a functionalized MWCNT concentration of 0.01 wt% at 50 °C compared with the base fluid. In addition, the photo-thermal energy conversion efficiency of the functionalized MWCNT nanofluid was higher than that of the nonfunctionalized one owing to its higher light absorption and thermal conductivity.

Darcy–Forchheimer Radiative Flow of Micropoler CNT Nanofluid in Rotating Frame with Convective Heat Generation/Consumption

Since 1991, from the beginning of the carbon nanotube era, this has been a focus point for investigation due to its synthetic and simple nature. Unique properties like good stiffness, high surface area, and resilience of carbon nanotubes (CNTs) have been investigated in many engineering applications such as hydrogen storage, composite material, energy storage, electrochemical super-capacitors, transistors, sensors, and field-emitting devices. Keeping in view these applications, we investigate single and multi-walled CNTs nanofluid flow having water as the base fluid between parallel and horizontal rotating plates with microstructure and inertial properties. The thermal radiation effect is considered for variable phenomenon of heat generation/consumption. The principal equations are first symmetrically transformed to a system of nonlinear coupled ordinary differential equations (ODEs), and then, Homotopy Analysis Technique (HAM) and numerical method are employed for solving these coupled equations. The obtained analytical and numerical results are explained graphically and through different tables. The HAM and numerical results show an excellent agreement. The Skin friction and the Nusselt number are numerically calculated and then analyzed with the already published results, and these results are found to be in agreement with one another. The impact of important parameters are shown graphically.

Photo-thermal performance evaluation on MWCNTs-dispersed microencapsulated PCM slurries for direct absorption solar collectors

Thermal energy storage is fundamentally important to overcome the intermittence and instability of solar thermal energy. To explore the photo-thermal conversion performance of nanofluids after the addition of microencapsulated phase change materials (MPCMs) in direct absorption solar collectors (DASCs), hybrid slurries involving MPCMs dispersed in ethanol/water mixture-based multi-walled carbon nanotube (MWCNT) nanofluid were prepared and experimentally tested. It was found that the temperature rise of hybrid MPCM-MWCNT slurry with respect to the base fluid (ethanol/water mixture) was lower than that of the pure MWCNT nanofluid owing to the high reflectivity of MPCM surface and PCM melting induced heat absorption. At the thermal discharging stage, however, the terminal temperatures of hybrid slurries were higher than that of MWCNT nanofluid and increased with the MPCM concentration. Compared with the base fluid, the corresponding terminal temperature was about 4.6℃ higher for the hybrid slurry containing 15 wt% MPCMs. Therefore, the addition of MPCMs in nanofluids become a potential solution for direct absorption solar thermal applications if the MPCM surface is well coated with nano-layer materials having high optical absorption capability.

Experimental study on thermal properties and electrical conductivity of stabilized H2O-solar glycol mixture based multi-walled carbon nanotube nanofluids: developing a new correlation

The main aim of this present work is to explore the influence of dispersion of MWCNTs in a mixture of water-solar glycol (70:30) on its electrical conductivity and thermophysical properties such as density, rheology and thermal conductivity. The MWCNTs were seeded with a various weight percentage of 0.15, 0.3 and 0.45 via a common two-stage synthesis technique. The homogeneous stability of MWCNTs based nanofluids was confirmed by high-resolution scanning electron microscopy and ultraviolet-visible spectroscopy. The density of solar glycol and H2O mixture based MWCNTs nanofluids were measured with standard borosil volumetric flask via weighing balance mechanism and the experimental findings displayed a good agreement with the well-known correlation of Pak and Cho owing to the natural packing of H2O inside the nanomaterial in a limited quantity. The thermal conductivity of 0.45 wt. % MWCNTs seeding got augmented by 19.12% at ambient temperature while the electrical conductivity got augmented by 93.54% at 50 °C. Therefore, the augmentation in the thermal conductivity of water/solar glycol mixture with 0.45 wt. % MWCNTs seeding is because of the kinetics of nanomaterial accumulation and fluid layering. In addition, mathematical correlations were recommended for estimating the ratio of the thermal conductivity and viscosity of the nanofluid at different weight fractions.

Assessment of Measurement Accuracy of a Micro-PIV Technique for Quantitative Visualization of Al2O3 and MWCNT Nanofluid Flows

Nanofluids, which are liquids containing nanoparticles, are used to modify heat transfer performance in various systems. To explain the mechanism of heat transfer modification with nanofluids, many theories have been suggested based on numerical simulations without experimental validation because there is no suitable experimental method for measuring the velocity fields of nanofluid flows. In this study, the measurement accuracy of micro-particle image velocimetry (μ-PIV) is systemically quantified with Al2O3 and multi-walled carbon nanotube (MWCNT) nanofluids. Image quality, cross-correlation signal-to-noise ratio, displacement difference, and spurious vector ratio are investigated with static images obtained at various focal plane positions along the beam pathway. Applicable depth is enough to investigate micro-scale flows when the concentrations of Al2O3 and MWCNT nanofluids are lower than 0.01% and 0.005%, respectively. The velocity fields of Hagen–Poiseuille flow are measured and compared with theoretical velocity profiles. The measured velocity profiles present good agreement with the theoretical profiles throughout. This study provides the criteria for μ-PIV application and demonstrates that μ-PIV is a promising technique for measuring the velocity field information of nanofluids.

Enhanced thermal conductivity of flexible cotton fabrics coated with reactive MWCNT nanofluid for potential application in thermal conductivity coatings and fire warning

It is a challenge to fabricate a flexible and smart cotton fabric sensor with improved thermal conductivity while retaining electrical insulation. Herein, reactive multiwall carbon nanotube (MWCNT) nanofluid exhibiting soft glassy rheological behavior was successfully synthesized through simultaneous surface modification by (3-aminopropyl) triethoxysilane and dimethyloctadecyl[3-(trimethoxysilyl)propyl] ammonium chloride followed by ion-exchange reaction with nonylphenol polyoxyethylene ether sodium sulfate. Then, MWCNT nanofluid was used to coat MWCNT nanofluid/cotton fabrics by simple spraying. It was found that the addition of MWCNT nanofluid improved the thermal conductivity while preserving electrical insulation of the cotton fabric. The maximum thermal conductivity of MWCNT nanofluid/cotton fabric is 2.42 times that of cotton fabric. It was also observed that surface grafted non-conductive silane molecules and organic ion salt of MWCNT hinder the MWCNT inter-contacting with each other to form a conductive network for retaining electrical insulation. In addition, during the combustion process of cotton fabric, surface grafted organic molecules of MWCNT nanofluid began to decompose and thus promote the formation of the MWCNT conductive network, indicated by the presence of electric current. This could be valuable as a low-voltage DC power source for potential applications in fire alarm sensors.

Dispersion and stability of solvent-free multi-walled carbon nanotube nanofluids

The fluidity of solvent-free nanofluids is related to the structure between and within molecules consisting of graftable groups or groups that can be exchanged. Research into controlling the fluidity by ion exchange have been reported. Indeed, it may be possible to control fluidity by surface grafting. This paper develops a facile method to prepare solvent-free multi-walled carbon nanotube nanofluids (MWCNTFs) with liquid-like behavior using surface grafted polyethylene glycol-substituted tertiary amines onto multi-walled carbon nanotubes (MWCNTs). The morphology, thermal stability, dispersibility and rheological behavior of MWCNTFs are investigated. It is found that MWCNTFs possess stable thermal properties and can flow without solvent existence. More importantly, the nanofluids show good dispersion and stability in water or other organic solvents for weeks due to the amphiphilic properties of the grafted groups. It is proposed that the facile method, which endows MWCNTs with better properties, will pave the way for developing high performance MWCNTs composites in the future.

A study on the potential of carbon-based nanomaterials for enhancement of evaporation and water production

In the present study, the performance of water based-nanofluids containing four different types of carbon nanostructures for solar vapor generation has experimentally been investigated. The considered nanofluids are multi-walled carbon nanotube, single-walled carbon nanotube, graphene nanoplate and graphene oxide. Nanofluids with three nanoparticle mass concentrations of 0.001%, 0.002%, and 0.004% were prepared and their evaporation characteristics were investigated for solar radiation intensities in the range of 1.5 and 3.5 Suns. The results indicated that the multi-walled carbon nanotube nanofluid with a mass concentration of 0.004% provides the highest evaporation rate with the maximum total efficiency of 94% at 3.5 Suns. The total efficiencies for nanofluids containing the single-walled carbon nanotube, graphene nanoplate and graphene oxide at similar conditions and that of pure water, respectively, are about 91%, 90%, 81% and, 54%. Furthermore, it is observed that for the mass concentration of 0.004%, the evaporation rate with respect to water increases to about 72%, 63%, 58% and 36%, respectively, for the multi-walled carbon nanotube, the single-walled carbon nanotube, graphene nanoplate and graphene oxide nanofluids. As far as the sensible heat is concerned, graphene oxide shows the most considerable sensible heating efficiency at the mass concentration of 0.004% with the maximum fluid bulk temperature rise of 20.5 °C, which is 40% higher than that of water. Finally, it was found that increasing the radiation intensity from 1.5 to 3.5 Suns improves the evaporation rate; however, the sensible heat efficiency is more influenced such that the evaporation efficiency declines. The quality of the produced water from a seawater sample is also examined and it was shown that it is well below the limitations of the drinking water standards.

Application of large-scale prepared MWCNTs nanofluids in solar energy system as volumetric solar absorber

Multi-walled carbon nanotubes (MWCNTs) nanofluids suffer from low dispersion and short shelf life which hinder their large-scale application in solar energy system. To respond this, in this study a novel method of MWCNTs nanofluids preparation has been designed. It is a one-pot method by stirred media mill technique achieving the objective of low cost and scalable for nanofluids production, in which nearly 1 L MWCNTs nanofluids of 3 wt% could be gotten in a laboratory-scale production process. Apart from with concentration adjustability and long-lasting stability, obtained MWCNTs nanofluids also displayed superior optical properties. It showed that the average extinction coefficient of 0.01 wt% milling-treated MWCNTs nanofluid was 7.49 cm-1, which was obviously higher than that of 0.01 wt% acid-treated sample with 6.55 cm-1. Especially, the spectral analysis revealed that milling-treated MWCNTs nanofluids had better energy absorption capacity in visible and near-infrared regions. Moreover, the evaluation of solar energy absorption fraction showed that 0.01 wt% MWCNTs nanofluid could absorb nearly 100% incident energy, when fluid thickness was more than 0.5 cm. It means that MWCNTs nanofluids could be tailored easily for volumetric solar receiver to achieve optimal design. Furthermore, the solar-thermal conversion tests were conducted under natural solar radiation and a high conversion efficiency (95%) was obtained at first 10 min in 0.02 wt% MWCNTs nanofluids. It is worth to note that the performance degradation of high concentration MWCNTs nanofluids did not happen during conversion tests. Such results revealed that MWCNTs nanofluids were prepared successfully in large-scale and the high performance of them showed their application potential in solar energy system.

MHD Thin Film Flow and Thermal Analysis of Blood with CNTs Nanofluid

Our main objective in the present work is to elaborate the characteristics of heat transport and magneto-hydrodynamics (MHD) finite film flow of human blood with Carbon Nanotubes (CNTs) nanofluids over a stretchable upright cylinder. Two kinds of CNTs nanoparticles, namely (i) SWCNTs (single walled carbon nanotubes) and (ii) MWCNTs (multi walled carbon nanotubes), are used with human blood as a base liquid. In addition, a uniform magnetic field (B) has been conducted perpendicularly to the motion of nanoliquid. The transformation of the partial differential structure into a non-linear ordinary differential structure is made by using appropriate dimensionless quantities. The controlling approach of the Homotopy analysis method (HAM) has been executed for the result of the velocity and temperature. The thickness of the coating film has been kept variable. The pressure distribution under the variable thickness of the liquid film has been calculated. The impacts of different variables and rate of spray during coating have been graphically plotted. The coefficient of skin friction and Nusselt number have been presented numerically. In addition, it is noticed that the thermal field of a nanoliquid elevates with rising values of ϕ and this increase is more in SWCNTs nanofluid than MWCNTs nanofluid.

Experimental study on heat transfer characteristics of hybrid nanofluid impinging jets

Silver (Ag)-multiwall carbon nanotube/water hybrid nanofluids were used as a heat transfer media. The stability of the hybrid nanofluids was tested by comparing the matching ratios of different Ag particles and multiwall carbon nanotube particles. The optimal ratio of mixed solution and deionized water were selected at different mass fractions. The experimental study analyzes conventional impinging jets (CIJs) and swirling impinging jets (SIJs) on the conditions of different heat exchange surfaces, different length to diameter (L/D) values and different swirling ratios of twisted ribbons. The analysis also includes the effects of adding different dispersants on mixed nanofluids. The results shows that the thermal conductivity of Ag-multiwall carbon nanotube/water hybrid nanofluids is higher than that of multiwall carbon nanotube nanofluids. Furthermore, the heat transfer efficiency increases with the increasing of mass fraction. Under the same experimental conditions, the effect of heat transfer by swirling impinging jets was better than that of conventional impinging jets. The arc target surface heat transfer coefficient was higher, and L/D = 4 was the best nozzle size to target the surface space ratio. Finally, y/w = 3 was the best spiral structure of the built-in twisted ribbon.

Membrane Absorption Coupling Process for CO2 Capture: Application of Water-Based ZnO, TiO2, and Multi-Walled Carbon Nanotube Nanofluids

In this work, stable water-based zinc oxide (ZnO), titania (TiO2), and multi-walled carbon nanotube (MWCNT) nanofluids are prepared and examined as CO2 absorbents in a polypropylene hollow fiber membrane contactor. Different operating variables, such as liquid flow rate, gas flow rate, and concentration of nanoparticles, and their effects on CO2 molar flux are investigated. The long-term stability of nanofluids is monitored using ultraviolet–visible spectroscopy. Also, ζ-potential measurements and sediment photography are applied to confirm the results of nanofluid stability. Dynamic light scattering is used to determine the size distribution of dispersed nanoparticles. The results show that the increase in the nanoparticle concentration to 0.15 wt % has a favorable effect on CO2 absorption efficiency as a result of the increase in Brownian motion and other related mechanisms. However, it adversely affects the CO2 absorption by lowering the nanofluid stability at higher concentrations. The obtained result...

Experimental Assessment of the Thermo-Hydraulic Performance of Automobile Radiator with Metallic and Nonmetallic Nanofluids

The overall heat transfer of a cross flow heat exchanger can be enhanced by using the nanofluids as coolant, which finds application in reducing the size and weight of automobile radiator. However, improving the heat transfer using nanofluids can be accompanied by simultaneous variations in the required pumping power. This study experimentally evaluates the thermo-hydraulic performance of three nanofluids—metallic (copper, aluminum) and nonmetallic (multiwalled carbon nanotube (MWCNT))—as coolant for an automobile radiator by utilizing an in-house test rig. An enhancement in overall heat transfer coefficient can be observed with nanocoolants (nanofluid as coolant), compared to the de-ionized water at the same Reynolds number. The maximum enhancement in the overall heat transfer coefficient was observed to be 40, 29, and 25% for MWCNT, copper, and aluminum nanofluids, respectively. The thermal performance of coolants was also compared with the same pumping power criterion. The overall heat transfer coefficient of nanofluids were higher than basefluid at low pumping power range and the trend changes with increase in the pumping power. The present study shows that the heat transfer characteristics at the same Reynolds number as well as at the same pumping power needs to be considered for the selection of appropriate nanocoolant for automobile radiator application.