COOLING OF AN INTERNAL COMBUSTION ENGINE USING NANOFLUIDS: A REVIEW

Back to Index COOLING OF AN INTERNAL COMBUSTION ENGINE USING NANOFLUIDS: A REVIEW RAHUL TARODIYA *, JAHAR SARKAR Department of Mechanical Engineering Institute of Technology-BHU, Varanasi 221005, India *Email: rtarodiya@gmail.com, Mob: 9559895987 ABSTRACT Researches in heat transfer have been carried out over e previous several decades, leading to e development of e currently used heat transfer enhancement techniques. The use of additives is a technique applied to enhance e heat transfer performance of base fluids. Recently, as an innovative material, nanometer-sized particles have been used in suspension in conventional heat transfer fluids. The fluids wi ese solid-particle suspended in em are called nanofluids. The suspended metallic or nonmetallic nanoparticles change e transport properties and heat transfer characteristics of e base fluid. One of important applications of nanofluid is for automotive cooling system. This review summarizes recent developments in research on automotive cooling system using nanofluid as a coolant. Aim of is review is to suggesting some possible reasons why e suspended nanoparticles can enhance e heat transfer of conventional fluids and to provide a guide line or perspective for future research in internal combustion engine. Keywords: Nanofluids; Heat transfer; Thermal conductivity; Internal combustion engine; Radiator. Nomenclature Pr Prandtl number Re Reynold number T temperature ( o C) Subscripts nf nanofluid EG eylene glycol w water 75

1. INTRODUCTION Continuous technological development in automotive industries has increased e demand for high efficiency engines. A high efficiency engine is not only based on its performance but also for better fuel economy and less emission. Reducing a vehicle weight by optimizing design and size of a radiator is a necessity for making e world green. Addition of fins is one of e approaches to increase e cooling rate of e radiator. It provides greater heat transfer area and enhances e air convective heat transfer coefficient. However, traditional approach of increasing e cooling rate by using fins and microchannel has already reached to eir limit [1]. In addition, heat transfer fluids at air and fluid side such as water and eylene glycol exhibit very low ermal conductivity. As a result ere is a need for new and innovative heat transfer fluids for improving heat transfer rate in an automotive car radiator. Nanofluids seem to be potential replacement of conventional coolants in engine cooling system. Recently ere have been considerable research findings highlighting superior heat transfer performances of nanofluids. Nanofluids can be used for a wide variety of industries, ranging from transportation to energy production and in electronics systems like microprocessors, Micro- Electro-Mechanical Systems (MEMS) and in e field of biotechnology. Recently, e number of companies at observe e potential of nanofluids technology and eir focus for specific industrial applications is increasing. In e transportation industry, nanocars, GM and Ford, among oers are focusing on nanofluids research projects. Nanofluids can be used to cool automobile engines and welding equipment and to cool high heat-flux devices such as high power microwave tubes and high-power laser diode arrays. A nanofluid coolant could flow rough tiny passages in MEMS to improve its efficiency. The measurement of nanofluids critical heat flux (CHF) in a forced convection loop is useful for nuclear applications. If nanofluids improve chiller efficiency by 1%, a saving of 320 billion kwh of electricity or an equivalent 5.5 million barrels of oil per year would be realized in e US alone. Nanofluids find potential for use in deep drilling application. A nanofluid can also be used for increasing e dielectric streng and life of e transformer oil by dispersing nanodiamond particles. Application areas can be summarized as [2]: Heat-transfer, Tribological, Surfactant and coating, Chemical, Process/extraction, Environmental (pollution cleaning), Bio- and pharmaceutical, and Medical (drug delivery and functional tissue cell interaction). Yu et al, [3] first reviewed e potential of nanofluid for transportation. He reported at about 15-40% of heat transfer enhancement can be achieved by using various types of nanofluids. Wi ese superior characteristics, e size and weight of an automotive car radiator can be reduced wiout affecting its heat transfer performance. This translates into a better aerodynamic feature for design of an automotive car frontal area. Coefficient of drag can be minimized and fuel consumption efficiency can be improved. Anoer review articles about e various current and future applications of nanofluids have been presented by Loeng et al [4] and Wong et al [5]. However, detailed review/information regarding automotive cooling and lubrication using 76

nanofluids is scare in open literature. Therefore, e present review summarizes recent developments trend in research on automotive cooling and lubrication system using nanofluids. 2. NANOFLUID AS RADIATOR COOLANT 2.1 THEORETICAL INVESTIGATION: Ollivier et al. [6] numerically investigated e possible application of nanofluids as a jacket water coolant in a gas spark ignition engine. Auors performed numerical simulations of unsteady heat transfer rough e cylinder and inside e coolant flow. Auors reported at because of higher ermal diffusivity of nanofluids, e ermal signal variations for knock detection increased by 15% over at predicted using water alone. Saripella et al. [7] modeled e cooling system of class 8 truck engine using flow master computer code. Auors done numerical simulation to replace e standard coolant, 50/50 mixture of eylene-glycol and water, wi nanofluid comprised of CuO nanoparticles suspended in a base fluid of 50/50 mixture of eylene-glycol and water. The auors show at ere is a 5% increase in engine horsepower rejected to e coolant using e nanofluid compared to e standard coolant as shown in Table 1. He also showed a reduction in pump power as much as 88% wi nanofluid compared to base fluid alone (Table 2) and possible reduction of surface area of e air side of e radiator due to increased heat transfer coefficient of nanofluids compared to base fluid alone. Table 1 Increased engine heat rejection wi Nanofluids Table 2 Reduced pump speed wi nanofluid 77

Table 3 Reduced radiator air side area wi nanofluids Leong and Saidur [8] investigated e heat transfer enhancement of an automotive car radiator operated wi nanofluid-based coolants. In eir investigation, ey compared nanofluids (wi eylene glycol e base fluid) to eylene glycol (i.e. base fluid) alone. They observed at, about 3.8% of heat transfer enhancement could be achieved wi e addition of 2% copper particles in a base fluid at e Reynolds number of 6000 and 5000 for air and coolant respectively. They also show at almost 18.7% reduction of air frontal area is achieved by adding 2% copper nanoparticles at Reynolds number of 6000 and 5000 for air and coolant respectively. In addition to at ey also found at additional 12.13% pumping power is needed for a radiator using nanofluid of 2% copper particles at 0.2 m 3 /s coolant volumetric flow rate compared to at of e same radiator using only pure eylene glycol coolant. Das and Strandberg [9] compared e performance of hydronic finned-tube heating units wi nanofluids wi a conventional heat transfer fluid comprised of 60% eylene glycol and 40% water, by mass (60% EG) using a maematical model. The model predicts at finned-tube heating output wi Al 2 O 3 /60% EG nanofluid is superior compared to at of e heating capacity wi CuO/60% EG nanofluid, and of e base fluid. Finned-tube heating capacities wi e CuO/60% EG and Al 2 O 3 /60% EG nanofluid are superior to at wi e base fluid at all concentrations examined. For bo nanofluids, heating capacity increases wi nanoparticle volumetric concentration. Vajjha & Das [10] numerically studied a ree-dimensional laminar flow and heat transfer wi two different nanofluids, Al 2 O 3 and CuO, in an eylene glycol and water mixture circulating rough e flat tubes of an automobile radiator and evaluate eir superiority over e base fluid. They shows at Heat transfer for Al 2 O 3 and CuO nanofluids wi varying particle volumetric concentrations exhibit substantial increase in e average heat transfer coefficient wi concentration. For example, at a Reynolds number of 2000, e percentage increase in e average heat transfer coefficient over e base fluid for a 10% Al 2 O 3 nanofluid is 94% and at for a 6% CuO nanofluid is 89%. For e same amount of heat transfer, e pumping power requirement is 82% lower for a Al 2 O 3 nanofluid of 10% concentration and 77% lower for a CuO nanofluid of 6% concentration when compared to e base fluid. Zhou et al. [11] have done a numerical simulation meod to study e use of nanofluids for cooling of an internal combustion engine. They reported at e application of nanofluids significantly enhanced e heat transfer, and e effect was larger wi an increasing 78

concentration of nanoparticles. The pumping power of e cooling system was increased by e use of nanofluids, but is can be accepted by considering e enhanced heat transfer. In e same manner Peng and Liu [12] have done e simulation of cooling effects of water, TiO 2 nanofluid, Al 2 O 3 nanofluid and CuO nanofluid and ey show at compared to water by using TiO 2, Al 2 O 3 and CuO nanofluid, e average surface heat transfer coefficient is increased by 10.82%, 8.43% and 11.24%, and correspondingly e pump power is increased only by 1.06%, 1.30% and 1.98%, respectively. It is clear at e heat transfer coefficient increases significantly at a tiny loss of pump power wi nanofluid as coolant, which is beneficial to e heat exchange of cooling system. 2.2 EXPERIMENTAL INVESTIGATION: Putra and Maulana [13] have done e measurement of forced convective coefficient on nanofluid by using car radiator in cross flow arrangement for water based nanofluid containing Al 2 O 3 Nanoparticles. They show at e enhancement in heat transfer convective coefficient compared to e base fluid 31-48% for 1% particle concentration and 52-79% for 4% particle concentration. Zhong et al. [14] study heat transfer effect of e nanofluid in internal combustion engine cooling system. Auors reported at e heat transfer capability of nanofluid is 4.6% and 19.0% higher an ose of water and antifreeze under 85 C inlet temperature, and 63.7% higher an at of antifreeze when e inlet temperature raise to 120 C. In e similar manner, Zhong et al. [15] experimentally study on heat exchange enhancement of nanofluids in vehicle oil cooler and ey reported at e nanoparticle addition can efficiently enhance heat exchange capability of e base fluid, and e enhancement effect increases wi particle volume fraction increasing. Under different inlet temperatures and temperature differences, bo heat exchange capacity and heat exchange coefficient for e 5% nanofluids are higher an conventional coolants (water and antifreeze). Increasing volumetric fraction may also raise e viscosity and flow resistance of e nanofluids. Peyghambarzadeh and Hashemabadi [16] experimentally performed e forced convection heat transfer in a car radiator and ey showed e heat transfer performances of pure water and pure EG comparison wi eir binary mixtures. Additionally different amounts of Al 2 O 3 nanoparticle have been added into ese base fluids and its effects on e heat transfer performance of e car radiator have been determined. They reported at by e addition of only 1 vol.% of Al 2 O 3 nanoparticle into e water or EG, an increase in Nusselt number of about 40% in comparison wi e pure water and pure EG as shown in Figure 1. They also found at an increase in e fluid inlet temperature slightly improves e heat transfer performance. Such as by increasing e inlet temperature of water based nanofluids from 35 C to 50 C can enhance Nusselt number up to 16%. For EG based nanofluids, e temperature elevation from 45 to 60 C creates maximum enhancement of 7% as shown in Figure 2. 79

Fig.1 Variations of Nusselt number at different Reynolds number as a function of nanoparticle concentration. A) Water based nanofluids. B) EG based nanofluids. Fig. 2 Effect of inlet temperature on Nusselt number: A) Water based nanofluid at 1 vol.% concentration, B) EG based nanofluid at 0.7 vol.% concentration 3. NANOFLUID AS ENGINE LUBRICATING OIL: Engine oil based nanofluid improves e heat transfer and may reduce friction and wear, alough research on is field is limited. Wu and Kao [17] studied application of TiO 2 nanofluid as an additive for engine lubricating oil for reducing friction and wear. The result was shown at e TiO 2 nanoparticle additive exhibited lower friction force as compared to original oil. Their experiment showed at a smaller particle size exhibits better friction reduction wi particle size ranging from 59 to 220 nm. 80

4. CONCLUDING REMARKS: Applications of nanofluids as coolant and lubricant in IC engine are reviewed in is study. Based on literatures, it has been found at by using nanofluid as a coolant ere is an enhancement of heat transfer and happen wi e increase in its nanoparticle concentration which result reduced e size of e cooling system in e automotive application. Most of e auors are performed eir investigation by taking finned tube in cooling system, ere should be more work required in is field for different geometry of e fin such as by considering louver angle, study based on different fin spacing. It was also found at ere are inconsistencies in e reported eoretical and experimental results published by many researchers. Exact mechanism of enhanced heat transfer for nanofluids is still unclear as reported by many researchers. However, it should be noted at many challenges need to be identified and overcome for different applications. Nanofluids stability and its production cost are major factors at hinder e commercialization of nanofluids. By solving ese challenges, it is expected at nanofluids can make substantial impact as coolant and engine oil in an automotive application. REFERENCES: [1] D.P. Kulkarni, R.S. Vajjha, D.K. Das, D. Oliva, Application of aluminum oxide nanofluids in diesel electric generator as jacket water coolant, Applied Thermal Engineering 28 (14-15) (2008) 1774-1781. [2] Kostic. www.kostic.niu.edu/drnanofluids; 2009 [14.11.2009]. [3] W. Yu, D.M. France, S.U.S. Choi, J.L. Routbort, Review and Assessment of Nanofluid Technology for Transportation and Oer Applications (No. ANL/ ESD/07-9). Energy System Division, Argonne National Laboratory, Argonne, 2007. [4] Kaufui V.Wong and Omar De Leon, A Review on Applications of Nanofluids: Current and Future, Advances in mechanical engineering 10.1155/2010/519659. [5] R. Saidur, K. Y. Leong, H.A. Mohammad, A review on applications and challenges of nanofluids, Renewable and Sustainable Energy Reviews 15 (2011) 1646-1668. [6] Ollivier E, Bellettre J, Tazerout M, Roy GC. Detection of knock occurrence in a gas SI engine from a heat transfer analysis. Energy Convers Manage 47(7 8) (2006) 879 93. [7] S.K.Saripella, W.Yu, J.L. Routbort, D.M. France, Rizwan-uddin, Effects of Nanofluid Coolant in a Class 8 Truck Engine, SAE technical paper 2007-01-2141. [8] K.Y. Leong, R. Saidur, S.N. Kazi, A.H. Mamun, Performance investigation of an automotive car radiator operated wi nanofluid-based coolants (nanofluid as a coolant in a radiator), Applied Thermal Engineering 30 (2010) 2685 2692. [9] R. Strandberg, D.K. Das, Finned tube performance evaluation wi nanofluids and conventional heat transfer fluids, International Journal of Thermal Sciences 49 (2010) 580 588. 81

Friday, 14 October 2011 [10] R.S. Vajjha, D.K. Das, P.K. Namburu, Numerical study of fluid dynamic and heat transfer performance of Al2O3 and CuO nanofluids in e flat tubes of a radiator, International Journal of Heat and Fluid Flow 31 (2010) 613 621. [11] J. Lv, L. Zhou, M. Bai, W. J. Liu, Z. Xu, Numerical simulation of e improvement to e heat transfer wiin e internal combustion engine by e application of nanofluids, journal of Enhanced Heat Transfer,17(1)(2010):93-109. [12] W.G.Peng, Y. C. Liu, Y.W. Hu, Y. R. He, Simulation of heat exchange enhancement using in engine cooling system, Harbin institute of technology 43(1) (2011):109-113. [13] N Putra, S Maulana, Heat transfer enhancement of nanofluids in car radiator. mechanical engineering paper 2010. [14] X. Zhong, L. X. Yu, Y. Zhang, J. X. Liu, Design of heat transfer experiment for nanofluid in diesel oil cooler, Chinese society of Internal Combustion Engine Engineering, 29(1)(2011):67-71. [15] X. Zhong, L. X. Yu, Experimental study on heat exchange enhancement of nanofluids in vehicle oil cooler, Chinese Internal Combustion Engine Engineering, 32(3)(2011):74-78. [16] S.M. Peyghambarzadeh, S.H. Hashemabadi, S.M. Hoseini, M. Seifi Jamnani, Experimental study of heat transfer enhancement using water/eylene glycol based nanofluids as a new coolant for car radiators, International communication of Heat and Mass transfer,article in press (2011). [17] Yuh-Yih Wu, Mu-Jung Kao, Using TiO2 Nanofluid Additive for Engine Lubrication Oil, Emerald Group Publishing Limited 63 (6) (2011). 82