ADVANCE COOLING OF RADIATORS BY USING COPPER-OXIDE NANOFLUIDS

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1 ADVANCE COOLING OF RADIATORS BY USING COPPER-OXIDE NANOFLUIDS P.Suganya, G.Subburaj, S.Ragupathy, T.Ajith, K.Vinothkambly, Assistant Professor, Department of Aeronautical Engineering, Student,Department of Aeronautical Engineering, Hindusthan College of Engineering and Technology, Hindusthan College of Engineering and Technology, Coimbatore, India. Coimbatore, India. Abstract - Current radiator designs are limited by requiring a large frontal area to meet cooling needs. Nowadays water and ethylene glycol have been used as a conventional coolants in an automobile radiator for many years. These heat transfer fluids offer low thermal conductivity and poor heat transfer characteristics. The development of advanced nanofluids, which have better conduction and convection thermal properties has a new opportunity to design a high energy efficient, light-weight radiator. This project will explore concepts of next-generation radiators that can adopt the high performance nanofluids. Keywords: Nanofluids, Conductivity, Efficiency Radiator, Cooling, Thermal I. INTRODUCTION The automotive industry is continuously involved in a strong competitive career to obtain the best automobile design in multiple aspects (performance, fuel consumption, safety, etc.). The aircooled heat exchangers found in a vehicle (radiator, AC condenser and evaporator, etc.) have an important role in its weight and also in the design of its frontal area. The use of nanofluids as coolants would allow for smaller size and better weight reduction of the radiators[1]. The use of high-thermal conductive nanofluids in radiators can lead to a reduction in the frontal area of the radiator up to 10%. The fuel saving is up to 5% due to the reduction in aerodynamic drag. Nanofluids have great potentials to improve automotive and heavy-duty engine cooling rates by increasing the efficiency, lowering the weight and reducing the complexity of thermal management systems. The improved cooling rates for automotive and truck engines can be used to remove more heat from higher horsepower engines with the same size of cooling system. Alternatively, it is beneficial to design more compact cooling system with smaller and lighter radiators. It is in turn benefit the high performance and high fuel economy of car and truck. Ethylene glycol or water based nanofluids have attracted much attention in the application as engine coolant, due to the lowpressure operation compared with a 50/50 mixture of ethylene glycol and water, which is universally used automotive coolant. The nanofluids has a high boiling point, and it can be used to increase the normal coolant operating temperature and then reject more heat through the existing coolant system. These novel and advanced concepts of coolants offer better heat transfer characteristics compared to conventional coolants. Eastman et al [4], Liu et al.[5], Hwang et al.[6], Yu et al[7]. And Mintsa et al.[8], observed great enhancement of nanofluids, thermal conductivity compared to conventional coolants. Enhancement of convective heat transfer was reported by Zeinali Heris et al.[9], Kim et al., Jung et al.[10] and Sharma et al.[11]. This paper review application of CopperOxide Nanofluids as coolant in Automobile radiator. II. RADIATOR Radiators are Heat exchangers used to transfer thermal energy from one to another medium for the purpose of cooling or heating. A fluid flowing through array of pipe where heat is transferred from one fluid to another. The proper design, operation and maintenance of heat exchangers will make the process energy efficient and minimize energy losses [23]. Coolant path and Components of an Automobile Engine Cooling System Page 43

2 There are three basic modes of heat transfer occurring in radiator which are conduction, convection, radiation. Conduction takes places between radiator tubes and fins. Most of the convection because of air flowing around the radiator fin and tube assembly and remaining due to the coolant flowing through the radiator tubes. Radiation occurs everywhere so we only focused about conduction and convection heat transfer. Q is the heat flow, h is the heat transfer coefficient, A is the heat transfer area, and T is the temperature difference in heat flow It can be stated from this equation that increased heat transfer can be achieved by: i) Increasing T, III. NANOFLUID Nano fluid is a fluid containing nanometersized particles, called nanoparticles. These fluids are engineered colloidal suspensions of nanoparticles in a base fluid. Nanofluid = Basefluid + Nanoparticle Nanoparticle is defined as a small object that behaves as a whole unit with respect to its transport and properties. Particles are further classified according to diameter. Where, Coarse particles (10,000 to 2,500 nm) Fine particles (2,500 to 100 nm) Ultrafine particles (1 to 100 nm) The nanoparticles used in Nano fluids are typically made of metals, oxides, carbides Common base fluids include water, ethylene glycol and oil. A. PREPARATION OF NANOFLUIDS There are two fundamental methods to obtain Nanofluids[3]: 1. Single-step direct evaporation method: In this method, the direct evaporation and condensation of the nanoparticulate materials in the base liquid are obtained to produce stable nanofluids. 2. Two-step method: In this method, first the nanoparticles are obtained by different methods and then are dispersed into the base liquid. B. OVERVIEW OF NANOFLUIDS In automotive systems where improved heat transfer could lead to smaller heat exchangers for cooling resulting in reduced weight and size of the vehicle. Many methods are available to improve heat transfer in processes. The flow of heat in a process can be calculated based on [14] ii) Increasing A, iii) Increasing h A greater temperature difference T can lead to increase the heat flow, but T is often limited by process or materials constraints. Therefore, T increased can only be achieved by decreasing the temperature of the coolant[14]. Maximizing the heat transfer area A is a common strategy to improve heat transfer, and many heat exchangers such as radiators and plate-and-frame heat exchangers are designed to maximize the heat transfer area. In aerospace and automotive systems, increasing the heat transfer area can only be achieved by increasing the size of the heat exchanger which can lead to unwanted increases in weight[14]. Heat transfer improvements can also be achieved by increasing the heat transfer coefficient h either by using more efficient heat transfer methods, or by improving the transport properties of the heat transfer material. For example, heat transfer systems which employ forced convection of a gas exhibit a greater heat transfer coefficient than systems which employ free convection of a gas. Alternatively, the heat transfer coefficient can be increased by enhancing the properties of the coolant for a given method of heat transfer. Additives are often added to liquid coolants to improve specific properties. For example, glycols are added to water to depress its freezing point and to increase its boiling point. The heat transfer coefficient can be improved via the addition of solid particles to the liquid coolant (i.e. nanofluids).[14-22] Q = ha T Page 44

3 Properties of air at 40 C, HMT data book p.no:34 Density (ρ) = 1.128kg/m3 Kinematic viscosity (v) = 16.96X10-6m2/s Prandtl number (p r) = Thermal conductivity (k ) = w/mk Reynolds number ( Re) = (UD)/v = (21.98X0.3)/(16.96X10-6) Re = 3.88X105 Thermal conductivity of various Materials (at 300K) [13] C. WHY WE USE NANO FLUID? The main goal or idea of using nano fluids is to attain highest possible thermal properties at the smallest possible concentrations (preferably<1% by volume) by uniform dispersion and stable suspension of nano particles (preferably<10 nm) in hot fluids. A nano fluid is a mixture of water and suspended metallic nano particles. Since the thermal conductivity of metallic solids are typically orders of magnitude higher than that of fluids it is expected that a solid/fluid mixture will have higher effective thermal conductivity compared to the base fluid. Nano fluids are extremely stable and exhibit no significant settling under static conditions, even after weeks or months[12]. IV. HEAT TRANSFER: Nusselt Number (Nu) = c(re)m(pr)0.333 From HMT data book page No for Re value is 3.88X105, corresponding C value is and m value is Nusselt Number Nu = (0.989)X(3.88X105)0.330X(0.699)0.333 Nu = Nu = (hd)/k = (h*0.3)/ h = w/m2k Heat Transfer(Q) = ha(tw-t ) = X(3.14X0.006X1.5)X(60-20) Q = w A. FOR PURE WATER Air temperature T = 20 c Velocity (U) = (𝜋𝐷𝑁)/60 U = 21.98m/s B. FOR NANO FLUID Air temperature T = 20 c Velocity (U) = (𝜋𝐷𝑁)/60 U = 21.98m/s Diameter = 0.006m Length = 1.5m Diameter = 0.006m Length = 1.5m Radiator surface Temperature(Tw) = 60 C Film temperature (Tf) = (Tw + T )/2 = ( )/2 Tf = 40 C Radiator surface temperature (Tw) = 50 C Film temperature (Tf) = (Tw +T )/2 = (50+20)/2 = 35 C Page 45

4 Properties of air at 35 C, HMT data book p.no:34 First the pure water is heated in the tank by using the water heater. Then the heated water is sent in to the radiator for cooling. The inlet and outlet Density (ρ) = kg/m3 temperature was measured in the digital thermometer Kinematic viscosity (v) = 16.48X10-6m2/s for calculations. Then the procedure was repeated for Prandtl number (p r) = 0.7 the CuO Nano fluid. Thermal conductivity(k) = w/mk B. EFFICIENCY Reynolds number ( Re) = (UD)/v = (21.98X0.3)/(16.48X10-6) Re = 4.001X10 Efficiency = (Twi-Two)/( Twi-Twba) 5 Where, Nusselt Number (Nu) = c(re)m(pr)0.333 From HMT data book page No for Re value is 4.001X105, corresponding C value is and m value is Twi = Temperature of Inlet, Two = Temperature of outlet, Twba = Temperature of atmosphere. Nusselt Number C.OBSERVATION Nu = (0.911)X(4.001X10 ) X(0.7) For Pure water Inlet temp: 500c Nu = Outlet temp: 430c Nu = (hd)/k Efficiency = (50-43)/(50-27) * = (h*0.3)/ h = w/m2k = 30.43% Heat Transfer (Q) = ha(tw-t ) For Nano fluid(cuo) Inlet temp: 500c = ( )X(3.14X0.006X1.5)X(50-20) Outlet temp: 33.50c Q = w Efficiency V. PROCEDURE = ( )/(50-27) * 100 = 71.73% TABLE1. COMPARISON PROPERTIES PUREWATER NANOFLUID high High Density High Efficiency 30% 70% Stability High Preparation Does not requires Requires Thermal conductivity Viscosity A. SCHEMATIC OF EXPERIMENTAL SETUP ADVANTAGES Page 46

5 1. High specific surface area and therefore more heat transfer surface between particles and fluids. Brazilian Journal of Chemical Engineering. Vol. 25, No. 04, pp , October - December, Reduced pumping power as compared to pure liquid to achieve equivalent heat transfer intensification. 3) P. sai sasank1, V.Govinda naik. Empirical Review on Car Radiator Using H2O and Al2O3. International Journal of Innovative Research in Science, Engineering and Technology. Vol. 3, Issue 10, October Reduced particle clogging as compared to conventional slurries, thus promoting system miniaturization. 4. Adjustable properties, including thermal conductivity and surface wet ability, by varying particle concentrations to suit different applications. 5. Heat transfer efficiency up to 45% in comparison with pure water. 5) Liu M-S, Lin MC-C, Huang I-Te, Wang C-C. Enhancement of thermal conductivity with CuO for nanofluids. Chem Eng Technol 2006;29(1): Overall heat transfer coefficient and heat transfer rate in engine cooling system increased with the usage of Nano fluids. 6) Hwang Y, Par HSK, Lee JK, Jung WH. Thermal conductivity and lubrication characteristics of nanofluids. Curr Appl Phys 2006;6S1:e APPLICATION 7) Yu W, Xie H, Chen L, Li Y. Investigation of thermal conductivity and viscosity of ethylene glycol based ZnO nanofluid. Thermochim Acta 2009;491(1 2):92 6. Some of the main cooling applications by using Nanofluids[2] 4) Eastman JA, Choi US, Thompson LJ, Lee S. Enhanced thermal conductivity through the development of nanofiuids. Mater Res Soc Symp Proc 1996;457:3 11. Space and defense Heat transfer intensification Transportation Electronic applications Nuclear systems cooling Industrial cooling 9) Zeinali Heris S, Nasr Esfahany M, Etemad SG. Experimental investigation of convective heat transfer of Al2O3/water nanofluid in circular tube. Int J Heat Fluid Flow 2007;28(2): Conclusion In this project Nanofluids are used as a coolant in Radiators because it has a high thermal conductivity due to its surface area compare to other Coolants such as water and Ethylene Glycol.It has been conclude that nanofluids have ability of high thermal conductivity so it can be proposed to use in various application. As heat transfer can be improved by nanofluids, it reduce size and weight of the automobile radiator, may results in increase the fuel economy. Reference 10) Kim D, Kwon Y, Cho Y, Li C, Cheong S, Hwang Y, et al. Convective heat transfer characteristics of nanofluids under laminar and turbulent flow conditions. Curr Appl Phys 2009;9(2,Supplement 1):e ) Jung J-Y, Oh H-S, Kwak H-Y. Forced convective heat transfer of nanofluids in microchannels. Int J Heat Mass Transfer 2009;52(1 2): ) Alpesh Mehta1, 2Dinesh k Tantia. Heat exchanger using nano fluid. Mehta et al, International Journal of 1) Rahul A. Bhogare, B. S. Kothawale. A Review on applications and challenges of Nano-fluids as coolant in Automobile Radiator. International Journal of Scientific and Research Publications, Volume 3, Issue 8, August ) Xiang-Qi Wang and Arun S. Mujumdar. A review on nanofluids - part ii: Experiments and applications. 8) Mintsa HA, Roy G, Nguyen CT, Doucet D. New temperature dependent thermal conductivity data for water-based nanofluids. Int J Therm Sci 2009;48(2): Advanced Engineering Technology 13) Ravi Adwani, Shri Krishna Choudhary. Experimental Investigation of Heat Transfer Rate In Automobile Radiator Using Nanofluid. International Journal of Innovative Science, Engineering & Technology, Vol. 1 Issue 6, August Page 47

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