Multiwalled Carbon Nanotube Nanofluid for Thermal Management of High Heat Generating Computer Processor

Minichannel heat sink geometries with varying fin spacing were tested with de‐ionized water and MWCNT (1 wt %) nanofluid to evaluate their performance with flow components of a liquid cooling kit. Four heat sinks with fin spacing of 0.2 mm, 0.5 mm, 1.0 mm, and 1.5 mm were used in this investigation. Heat sink base temperature was analogous to processor operating temperature which was the prime parameter of interest in this investigation. The base temperature decreased by reducing the fin spacing and using multiwalled carbon nanotube (MWCNT) nanofluid. The lowest value of heat sink base temperature recorded was 49.7 ^°C at a heater power of 255 W by using a heat sink of 0.2 mm fin spacing and MWCNT nanofluid as a coolant. Moreover, as a result of reduced fin spacing and using MWCNT nanofluid as a coolant the value of overall heat transfer coefficient increased from 1200 W/m²K to 1498 W/m²K, translating to about a 15% increase. The value of thermal resistance also dropped by reducing the fin spacing and using MWCNT nanofluid. The most important aspect of the study is that the heat sinks and MWCNT nanofluid proved to be compatible with the pump and radiator of the commercial CPU liquid cooling kit. The pump was capable to handle the pressure drop which resulted by reducing the heat sink fin spacing and by using MWCNT nanofluid. © 2013 Wiley Periodicals, Inc. Heat Trans Asian Res, 43(7): 653–666, 2014; Published online 11 November 2013 in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.21107     

Experimental and analytical investigation on an automobile radiator with CuO/EG‐water based nanofluid as coolant

In the present study, experimental and analytical thermal performance of automobile radiator using nanofluids is investigated and compared with performance obtained with conventional coolants. Effect of operating parameters and nanoparticle concentration on heat transfer rate are studied for water as well as CuO/EG‐water based nanofluid analytically. The results are presented in the form of graphs showing variations of net heat transfer rate for various coolant flow rate, air velocity, and source temperature for various CuO/EG‐water based nanofluids. Experimental results indicate that with the increase in coolant flow rate and air velocity, heat transfer rate increases, reaches maximum and then decreases. Experimental investigation of a radiator is carried out using CuO/EG‐water based nanofluids. Results obtained by experimental work and analytical MATLAB code are almost the same. Maximum absolute error in water and air side is within 12% for all flow condition and coolant fluids. Nusselt number of nanofluid is calculated using equation number 33[9]. The results obtained from experimental work using 0.2% volume CuO/EG‐water based nanofluids are compared with the results obtained from MATLAB code. The results show that the maximum error in the outlet temperature of the coolant and air is 12% in each case. Thus MATLAB code can be used for different concentration of nanofluids to study the effect of operating parameters on heat transfer rate. Thus MATLAB code developed is valid for given heat exchanger applications. From the results obtained by already validated MATLAB code, it is concluded that increase in coolant flow rate, air velocity, and source temperature increases the heat transfer rate. Addition of nanoparticles in the base fluid increases the heat transfer rate for all kind of base fluids. Among all the nanofluid analyzed in this study, water‐based nanofluid gives highest value of heat transfer rate and is recommended for the heat exchanger applications under normal operating conditions. Maximum enhancement is observed for ethylene glycol‐water (4:6) mixture for 1% volume concentration of CuO is almost equal to 20%. As heat transfer rate increases with the use of nanofluids, the heat transfer area of the radiator can be minimized.     

Performance Analysis of a Louvered Fin Automotive Radiator Using Hybrid Nanofluid as Coolant

This study deals with the theoretical enhancement of thermal performance using water‐based (50/50) volume fraction of Fe₂O₃, CuO, TiO₂, Ag, Cu in Al₂O₃ hybrid nanofluids as coolants for a louvered fin automobile radiator. The effects on thermophysical properties and various performance parameters, i.e., heat transfer, effectiveness, and pumping power of hybrid nanofluids have been compared with water. Among all studied hybrid nanofluids, Al₂O₃‐Ag/water hybrid nanofluid has higher effectiveness, heat transfer rate, pumping power, and pressure drop of 0.8%, 3%, 6%, and 5.6%, respectively, as compared to water and is followed by (50/50) volume fraction of Cu, CuO, Fe₂O₃, TiO₂ hybrid nanofluids as radiator coolant. For the same radiator size and heat transfer rate, coolant flow rate and pumping work decreases by 3%, 4%, respectively, for Al₂O₃‐Ag/water hybrid nanofluid and for the same coolant flow rate and heat transfer rate the radiator size decreases by 3% and pumping power increases by 3.4% for Al₂O₃‐Ag/water hybrid nanofluid as compared to water. Reduction in radiator size may lead to a reduction in radiator cost, engine fuel consumption, and environmental benefit.     

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

Abstract

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.     

Heat transfer enhancement using nanofluids in an automotive cooling system

The increasing demand of nanofluids in industrial applications has led to increased attention from many researchers. In this paper, heat transfer enhancement using TiO₂ and SiO₂ nanopowders suspended in pure water is presented. The test setup includes a car radiator, and the effects on heat transfer enhancement under the operating conditions are analyzed under laminar flow conditions. The volume flow rate, inlet temperature and nanofluid volume concentration are in the range of 2–8 LPM, 60–80 °C and 1–2% respectively. The results showed that the Nusselt number increased with volume flow rate and slightly increased with inlet temperature and nanofluid volume concentration. The regression equation for input (volume flow rate, inlet temperature and nanofluid volume concentration) and response (Nusselt number) was found. The results of the analysis indicated that significant input parameters to enhance heat transfer with car radiator. These experimental results were found to be in good agreement with other researchers' data, with a deviation of only approximately 4%.     

Experimental investigation of convective heat transfer coefficient of Al2O3/water nanofluid at lower concentrations in a car radiator

For many years, water and ethylene glycol were used as conventional coolants in automotive car radiators, but these coolants offer lower thermal conductivity than is required. This study is focused on the application of water‐based Al₂O₃ nanofluid at lower concentrations in a car radiator. The Al₂O₃ nanoparticles with an average diameter of 50 nm are dispersed in demineralized water at four different volume concentrations (0.1 vol. % to 0.4 vol. %) without any dispersant or stabilizer. Flow rate is varied in the range of 2 l/min to 5 l/min and inlet coolant temperature to the radiator is set to 50 °C, 60 °C, and 70 °C. The results show that the heat transfer coefficient increases with an increase in particle concentration, flow rate, and inlet temperature of coolant and the maximum increase in heat transfer coefficient is 45.87 % compared to pure water. However, the Nusselt number increases with the increase in particle concentration, Reynolds number, and inlet temperature of the coolant. In addition with the experimental study, a regression analysis is performed by using the ANOVA method and generates a correlation for the convective heat transfer coefficient.     

Performance effect on the TEG system for waste heat recovery in automobiles using ZnO and SiO2 nanofluid coolants

Enhancement in heat transfer of the cold side is vital to amplify the performance of a thermoelectric generator (TEG). With enriched thermophysical properties of nanofluids, significant improvement in heat transfer process can be obtained. The current study concerns the performance comparison of an automobile waste heat recovery system with EG‐water (EG‐W) mixture, ZnO, and SiO₂ nanofluid as coolants for the TEG system. The effects on performance parameters, that is, circuit voltage, conversion efficiency, and output power with exhaust inlet temperature, the total area of TEG, Reynolds number, and particle concentration of nanofluids for the TEG system have been investigated. A detailed performance analysis revealed an increase in voltage, power output, and conversion efficiency of the TEG system with SiO ₂ nanofluid, followed by ZnO and EG‐W coolants. The electric power and conversion efficiency for SiO ₂ nanofluid at an exhaust inlet temperature of 500K were enhanced by 11.80% and 11.39% respectively, in comparison with EG‐W coolants. Moreover, the model speculates that an optimal total area of TEGs exists for the maximum power output of the system. With SiO ₂ nanofluid as a coolant, the total area of TEGs can be diminished by up to 34% as compared with EG‐W, which brings significant convenience for the placement of TEGs and reduces the cost of the TEG system.     

Exergy and energy analysis of a wavy fin radiator with variously shaped nanofluids as coolants

The present study deals with the energy and exergy analysis of a wavy fin radiator deploying various shapes of Al₂O ₃‐water as nanocoolant. The effects of radiator effectiveness, pumping power, heat transfer rate, and performance index with variously shaped nanoparticles, mainly spherical, brick, and platelet, on coolant flow rates and air velocities have been investigated. Also, the impacts of entropy, second law efficiency, entropy generation number, and irreversibility on radiator performance analysis have been considered with steady‐state assumptions. Theoretical analysis revealed that the spherical particle–based nanocoolant showed 21.9%, and 18.2% higher effectiveness than platelet and brick nanocoolants. However, minimization in the entropy generation is observed in the platelet shape of the nanoparticle. The second law efficiency is 13% higher for the spherical nanocoolant compared with the brick nanocoolant. An optimum entropy generation number is found at a coolant flow rate of 13 l/min and then gradually decreases with an increase in the coolant flow rate. For all the considered operating parameters, the spherical nanoparticle showed a better performance than brick and platelet nanofluids as a radiator coolant. Due to the enhanced overall performance for the spherical nanofluid, it may be considered as a potential candidate for a radiator coolant.     

Study of the possibilities of thermal performance enhancement of flat plate solar water collectors by using of nanofluids as heat transfer fluid

The current work represents the simulation results of the thermal performances of flat-plate solar collector with heat transfer fluid–nanofluid (SiO₂ + water with 5% concentration) which is obtained experimentally [1]. The dependence of the outlet temperature and gained useful energy of heat transfer fluid (nanofluid) on the flow rates (10, 15 and 20 L/h) at different ranges of incident solar radiation (500–1000 W/m²) was obtained.     

Thermal analysis of natural convective air drying of shrinking bodies

In the present paper, a method for determination of external mass transfer coefficient h_m, during drying of shrinking bodies is described under simulated natural convective air drying conditions. The effects of sample shrinkage and air temperature on h_m during drying of cylindrical potato samples of diameter 0.01 m and length 0.05 m were experimentally investigated at air temperatures 40, 50 and 60°C. The mass transfer coefficient considering shrinkage was found to be independent of sample moisture content during drying process with mean values varying from 1.06 × 10^?7 to 2.60 × 10^?7 m s^?1 for temperature range 40–60°C. However, calculated values of h_m, with no shrinkage effect taken into account, were found to be overestimated. The experimental error in terms of percent uncertainty in mass transfer coefficient measurements was computed and found to be in the range of 0.4–2.0%. It was demonstrated that higher drying air temperature caused increased values of h_m and the variation followed Kelvin's law type relation. A mathematical model to predict the drying process of cylindrical bodies with convective mass transfer boundary condition at air–solid interface is proposed. The low range of various errors between the results of moisture content ratio predicted by the model and those obtained experimentally indicates that the present methodology is capable of simulation of drying kinetics of potato cylinders. Copyright © 2006 John Wiley & Sons, Ltd.     

Heat transfer enhancement for combined convection flow of nanofluids in a vertical rectangular duct considering radiation effects

In this paper, combined convective heat transfer and nanofluids flow characteristics in a vertical rectangular duct are numerically investigated. This investigation covers Rayleigh numbers in the range of 2 × 10⁶ ≤ Ra ≤ 2 × 10⁷ and Reynolds numbers in the range of 200 ≤ Re ≤ 1000. Pure water and five different types of nanofluids such as Ag, Au, CuO, diamond, and SiO₂ with a volume fraction range of 0.5% ≤ φ ≤ 3% are used. The three‐dimensional steady, laminar flow, and heat transfer governing equations are solved using finite volume method (FVM). The effects of Rayleigh number, Reynolds number, nanofluids type, nanoparticle volume fraction of nano‐ fluids, and effect of radiation on the thermal and flow fields are examined. It is found that the heat transfer is enhanced using nanofluids by 47% when compared with water. The Nusselt number increases as the Reynolds number and Rayleigh number increase and aspect ratio decreases. A SiO₂ nanofluid has the highest Nusselt number and highest wall shear stress while the Au nanofluid has the lowest Nusselt number and lowest wall shear stress. The results also revealed that the wall shear stress increases as Reynolds number increases, aspect ratio decreases, and nanoparticle volume fraction increases. © 2011 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.20354     

Performance assessment of parabolic dish and parabolic trough solar thermal power plant using nanofluids and molten salts

The present study has been conducted using nanofluids and molten salts for energy and exergy analyses of two types of solar collectors incorporated with the steam power plant. Parabolic dish (PD) and parabolic trough (PT) solar collectors are used to harness solar energy using four different solar absorption fluids. The absorption fluids used are aluminum oxide (Al₂O₃) and ferric oxide (Fe₂O₃)‐based nanofluids and LiCl‐RbCl and NaNO₃‐KNO₃ molten salts. Parametric study is carried out to observe the effects of solar irradiation and ambient temperature on the parameters such as outlet temperature of the solar collector, heat rate produced, net power produced, energy efficiency, and exergy efficiency of the solar thermal power plant. The results obtained show that the outlet temperature of PD solar collector is higher in comparison to PT solar collector under identical operating conditions. The outlet temperature of PD and PT solar collectors is noticed to increase from 480.9 to 689.7 K and 468.9 to 624.7 K, respectively, with an increase in solar irradiation from\ 400 to 1000 W/m². The overall exergy efficiency of PD‐driven and PT‐driven solar thermal power plant varies between 20.33 to 23.25% and 19.29 to 23.09%, respectively, with rise in ambient temperature from 275 to 320 K. It is observed that the nanofluids have higher energetic and exergetic efficiencies in comparison to molten salts for the both operating parameters. The overall performance of PD solar collector is observed to be higher upon using nanofluids as the solar absorbers. Copyright © 2015 John Wiley & Sons, Ltd.     

Effects of Thermodiffusion and Nanoparticles on Convective Instabilities in Binary Nanofluids

In this article, the effects of thermodiffusion of nanoparticles and solute in binary nanofluids and nanoparticles on the convective instabilities of a binary nanofluid is theoretically investigated. Thermodiffusion implies that mass diffusion is induced by thermal gradient, which is the so-called Soret effect. In order to analyze the convective instabilities of a binary nanofluid, a new stability criterion is obtained based on the linear stability theory and new factors g and f are proposed. The results show that the Soret effect of solute makes the binary nanofluids unstable significantly and the convective motion in a binary nanofluid sets in easily as the ratio of Soret coefficient of nanofluid to that of binary basefluid δ₄ increases for δ₄ > ?1. It is also found that with an increase of the volume fraction of nanoparticles, the nanofluid becomes stable, but at or near ψ _bf = ? 0.3 the state of nanofluid changes from stable to unstable. The results from the addition factor analysis show that an asymptotic point of ψ _bf where the maximum value of g diverges infinitely exists in the range of ? 1.2 < ψ _bf < ? 1.1 with given conditions. The binary addition factor g is always higher than the normal addition factor f, which means that the heat transfer enhancement by the Soret effect in binary nanofluids is more significant than that in normal nanofluids.     

Experimental analysis of SiO2-Distilled water nanofluids in a Polymer Electrolyte Membrane fuel cell parallel channel cooling plate

An experimental report on the thermal performance of Silicone Dioxide (SiO₂) nanofluid coolants based on a PEM fuel cell cooling system is presented. The aim of this study is to evaluate the feasibility of applying these nanofluids coolants as an alternative to conventional distilled water through detailed analysis of thermofluids behaviour in a simulated cooling plate environment. SiO₂ nanoparticles were dispersed in distilled water at 0.1%, 0.3% and 0.5% volume concentrations and tested in a parallel channel cooling plate system. A constant heat load was supplied to simulate a fuel cell stack thermal condition. At inlet flow conditions from 750 to 900 Reynolds number, the SiO₂ nanofluids reduced the average plate temperatures by 15%–20% compared to conventional water coolant. The nanofluids also increased the cooling effectiveness by a similar margin, as well as improving the bulk heat transfer coefficient to a range between 2700 and 4400 W m⁻². ^oC⁻¹. However, the required pumping power was also increased due to the added viscous effect. Through the Advantage Ratio (AR) analysis, it was concluded that the enhancement in heat transfer mechanics was more significant than the penalties in fluid flow dynamics. Thus, the SiO₂ nanofluids and the cooling plate design are possible options for advanced PEM fuel cell thermal management practice in future stack designs.     

A note on heat transfer modelling of Newtonian nanofluids in laminar free convection

The natural convection heat transfer of Newtonian nanofluids in a laminar external boundary-layer is investigated from the integral formalism approach. In particular, this study deals with γ-Al₂O₃/water nanofluids whose Newtonian behaviour was experimentally confirmed for particle volume fractions less than 4% [N. Putra, W. Roetzel, S.K. Das, Natural convection of nano-fluids, Heat and Mass Transfer 39 (2003) 775–784; S.Z. Heris, S.Gh. Etemad, M.N. Esfahany, Experimental investigation of oxide nanofluids laminar flow convective heat transfer, Int. Comm. Heat Mass Transfer 33 (2006) 529–535; R. Prasher, D. Song, J. Wang, Measurements of nanofluid viscosity and its implications for thermal applications, Appl. Phys. Lett. 89 (2006) 133108]. Based on a macroscopic modelling and under the assumption of constant thermophysical nanofluid properties, it is shown that special care has to be exercised in drawing generalized conclusions about the heat transfer enhancement with the use of nanofluids. It has been found that natural convection heat transfer is not solely characterized by the nanofluid effective thermal conductivity and that the sensitivity to the viscosity model used seems undeniable and plays a key role in the heat transfer behaviour.     

Natural convective heat transfer in trapezoidal enclosure of box-type solar cooker

This paper presents simple thermal analysis to evaluate the natural convective heat transfer coefficient, h_c12 for a trapezoidal absorber plate-inner glass cover enclosure of a double-glazed box-type solar cooker. Several indoor simulation experiments in steady state conditions have been performed to measure the temperatures of absorber plate, inner and outer glass covers, ambient air, electrical input supply and wind speed. The experimental data has been correlated by an equation of the form, Nu = CRaⁿ. The values of the constants C and n, obtained by linear regression analysis are used to calculate the convective heat transfer coefficient. The heat transfer analysis predicts that h_c12 varies from 4.84 to 6.23 W m^{−2 o}C⁻¹ for the absorber plate temperature from 54 to 141 ^oC. The results of h_c12 are compared with those of rectangular enclosure for the same absorber-inner glass cover temperatures and gap spacing. The study reveals that the values of convective heat transfer coefficient and top heat loss coefficient for rectangular enclosure are lower by 31–35% and 7% respectively.     

Experimental study on the thermo-physical properties of car engine coolant (water/ethylene glycol mixture type) based SiC nanofluids

The engine coolant (water/ethylene glycol mixture type) becomes one of the most commonly used commercial fluids in cooling system of automobiles. However, the heat transfer coefficient of this kind of engine coolant is limited. The rapid developments of nanotechnology have led to emerging of a relatively new class of fluids called nanofluids, which could offer the enhanced thermal conductivity (TC) compared with the conventional coolants. The present study reports the new findings on the thermal conductivity and viscosity of car engine coolants based silicon carbide (SiC) nanofluids. The homogeneous and stable nanofluids with volume fraction up to 0.5 vol.% were prepared by the two-step method with the addition of surfactant (oleic acid). It was found that the thermal conductivity of nanofluids increased with the volume fraction and temperature (10–50 °C), and the highest thermal conductivity enhancement was found to be 53.81% for 0.5 vol.% nanofluid at 50 °C. In addition, the overall effectiveness of the current nanofluids (0.2 vol.%) was found to be ~ 1.6, which indicated that the car engine coolant-based SiC nanofluid prepared in this paper was better compared to the car engine coolant used as base liquid in this study.     

Performance evaluation of photovoltaic/thermal–HDH desalination system

The efficiency of photovoltaic (PV) panel drops with increase in cell temperature. The temperature of the PV panel can be controlled with various cooling techniques. In the proposed work the PV panel is cooled by circulating water and the recovered heat energy is used to run a humidification and dehumidification desalination to produce distilled water from sea water (or) brackish water. This work deals with a detailed analysis of performance of combined power and desalination (Photovoltaic/Thermal–Humidification and Dehumidification) system. A mathematical model of PV/thermal–humidification dehumidification plant was developed and simulations were carried out in MATLAB environment. The performance of photovoltaic/ thermal desalination (Photovoltaic/Thermal–Humidification and Dehumidification) system was investigated under various solar radiation levels (800–1000 W/m²). For each solar radiation level the effect of mass flow rate of coolant water (30–110 kg/h) on water outlet temperature, PV efficiency, PVT thermal efficiency, distilled water production, and plant efficiency was studied. Results show that under each solar radiation level increasing coolant flow rate increases efficiency of PV panel and reduces the plant efficiency. The highest PV efficiency (16.598%) was reached under 800 W/m² at mass flow rate of 110 kg/h and the highest plant efficiency (43.15%) was reached under 800 W/m² at a mass flow rate of 30 kg/h. The maximum amount of distilled water production rate (0.82 L/h) was reached under 1000 W/m² at water mass flow rate of 30 kg/h.     

Experimental investigation and development of new correlation for thermal conductivity and viscosity of BioGlycol/water based SiO2 nanofluids

Nanofluids are a new class of engineered heat transfer fluids which exhibit superior thermophysical properties and have potential applications in numerous important fields. In this study, nanofluids have been prepared by dispersing SiO₂ nanoparticles in different base fluids such as 20:80% and 30:70% by volume of BioGlycol (BG)/water (W) mixtures. Thermal conductivity and viscosity experiments have been conducted in temperatures between 30 °C and 80 °C and in volume concentrations between 0.5% and 2.0%. Results show that thermal conductivity of nanofluids increases with increase of volume concentrations and temperatures. Similarly, viscosity of nanofluid increases with increase of volume concentrations but decreases with increase of temperatures. The maximum thermal conductivity enhancement among all the nanofluids was observed for 20:80% BG/W nanofluid about 7.2% in the volume concentration of 2.0% at a temperature of 70 °C. Correspondingly among all the nanofluids maximum viscosity enhancement was observed for 30:70% BG/W nanofluid about 1.38-times in the volume concentration of 2.0% at a temperature of 70 °C. The classical models and semi-empirical correlations failed to predict the thermal conductivity and viscosity of nanofluids with effect of volume concentration and temperatures. Therefore, nonlinear correlations have been proposed with 3% maximum deviation for the estimation of thermal conductivity and viscosity of nanofluids.     

Performance investigation of an automotive car radiator operated with nanofluid-based coolants (nanofluid as a coolant in a radiator)

Water and ethylene glycol as conventional coolants have been widely used in an automotive car radiator for many years. These heat transfer fluids offer low thermal conductivity. With the advancement of nanotechnology, the new generation of heat transfer fluids called, “nanofluids” have been developed and researchers found that these fluids offer higher thermal conductivity compared to that of conventional coolants. This study focused on the application of ethylene glycol based copper nanofluids in an automotive cooling system. Relevant input data, nanofluid properties and empirical correlations were obtained from literatures to investigate the heat transfer enhancement of an automotive car radiator operated with nanofluid-based coolants. It was observed that, overall heat transfer coefficient and heat transfer rate in engine cooling system increased with the usage of nanofluids (with ethylene glycol the basefluid) compared to ethylene glycol (i.e. basefluid) alone. It is observed that, about 3.8% of heat transfer enhancement could be achieved with the addition of 2% copper particles in a basefluid at the Reynolds number of 6000 and 5000 for air and coolant respectively. In addition, the reduction of air frontal area was estimated.