ADVANCE ENGINE COOLING SYSTEM

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Doon College of engineering and technology, Dehradun ... of vehicle. Key words: engine cooling, convection, carbon foam, radiator, Nano fluid.
International Journal of Advanced Technology & Engineering Research (IJATER) 1st International Conference on Research in Science, Engineering & Management (IOCRSEM 2014)

ADVANCE ENGINE COOLING SYSTEM AbhishekSaini Indian Institute of Technology, Patna [email protected] Krishna Singh Bisht Doon College of engineering and technology, Dehradun Mail id: [email protected] Sudhanshu Mishra Doon College of engineering and technology, Dehradun [email protected]

Abstract: The advancement in the field of aerodynamics and the engine Management system has made the modern vehicles lot more Faster as compare to one from the previous generations. The engine size has not increased much for reaching this much speed and torque requirement. Modern engine which produce efficient results in form of fuel efficiency and power to weight ratio runs at higher rpm and produce more power every cycle, this is a great boon but the amount of heat to be released from the engine to the surrounding increases with the increase in maximum power and speed requirement. That is why we need a more advance engine cooling system that can achieve proper cooling of the engine without any compromise with the aerodynamics shape of vehicle. Key words: engine cooling, convection, carbon foam, radiator, Nano fluid.

I.INTRODUCTION The transportation of goods and passengers using the modern highways where the speed requirement is lot higher with heavy load on the vehicle combined with problems in hot summers surely require an advance engine cooling system.

II. CONVENTIONAL ENGINE COOLING SYSTEM Combustion of air and fuel takes place inside the engine cylinder and hot gases are generated inside an internal combustion engine. The temperature of gases may rise up to around 2300-2500 ℃ , which is a very high temperature and may result into burning of oil film between the moving parts, pre combustion and may result into seizing or welding of the moving parts. So, this temperature must be reduced to lower values at which the engine will work properly and much more efficiently. Too much cooling is also not desirable since it reduces the thermal efficiency and reduces the

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vaporization of fuel thereby showing improper burning in form of black smoke in exhaust. Though the conventional engine cooling system which are either air cooled or water cooled are designed to remove about 30-35% of total heat that the engine dissipates, for now these system somehow fulfilling the existing requirements but with the advancement in the engine technology, increasing relative brake horse power (BHP), aerodynamic design requirements, emissions standards and energy crisis, it need advancement.  The radiators fitted in current engine cooling system are limited by air side resistance and require a large frontal area to meet cooling needs.  Current engine cooling system has limited heat dissipation and does not meet the requirement at high engine output.  Heat dissipation to volume ratio of the system is less.  At high speeds it is difficult to maintain the temperature of engine components.  Heat rejected by the system (about 35%of heat generated) is wasted to the atmosphere.

III. NEW RADIATOR DESIGN After developing several ideas those are based on changing the radiator construction or assisting some other components and process with the system. Such as changing the type of fin material used, their construction, use of turbocharger etc. The pros/cons of these design ideas were considered based upon the rate of heat dissipation and other limitations as per individual idea. From which these two design changes came to be much more promising than the rest of others. First one is the use of carbon foam fins instead of aluminum fins on current radiator design, more heat dissipation can be obtained. Because carbon foam increases the surface area exposed to the air. This is mainly due to the fact that the carbon foam is porous and allows the air to flow through it in addition to allowing the air to flow around it.

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International Journal of Advanced Technology & Engineering Research (IJATER) 1st International Conference on Research in Science, Engineering & Management (IOCRSEM 2014)

Apart from this the convective resistance between the coolant and the tubing can be reduced by Nano-fluids, a two-phase mixtures composed of very fine particles in suspension in a continuous and saturated liquids (water, ethylene glycol, engine oil), it may provide a very important enhancement in heat transfer as compared to conventional radiator coolant.

IV. DESIGN OF CONVENTIONAL RADIATOR Considering a conventional car radiator having Height of 365 mm and Width is 610 mm and depth of radiator (Lout) is 22mm. The fin dimensions are: thickness of fin(Thfin) is 0.35, pitch of fin is 1.52 mm, and separation between two adjacent tubes is 8mm and the tube wall thickness of 0.4 mm. The corresponding value of TH avg (hot water average temperature) is 90OCwithQd tubesas discharge rate fluid which is 1.30 x 10-3 m3/sec, Qreq= 35596 W at maximum brake horse power of 37969 W, the wind velocity which is mainly due to forward motion of vehicle is (Vair) 150 km/hr. Rate of heat transfer over the surface of radiator is given by: Q= U x A x ϴm And ϴm = TH avg- TC avg = 90– 40 = 50OC UA= 1 / Rtotal,(total thermal resistance between water and air) Where U is overall heat transfer coefficient between two fluids and ϴm is AMTD (arithmetic mean temperature difference) Rtotal = Rin + Rf, in + Rcond + Rout + Rf, out(1) Rin = 1/ (ℎin x A total,in) A total,in= .979416 Defining 𝑁𝑢 as nusselt number, Kair as thermal conductivity of air, Re as Reynolds number and Pr as Prandtl number Re = (ρ x v x Lc) / μ = .9937x104 Pr = ( μ x cp) / k = 1.8936 𝑵𝒖 = 3.66 + [ (0.668 (D/W) x Re x Pr) / (1 + 0.04 ( (D/W) x Re x Pr)2/3] 𝑁𝑢= 6.3366 𝑁𝑢= (ℎin x Lc) / k,Where Lc is characteristic length. ℎin= 2122.3 W/ m2 K Assuming Rin as convective resistance between the water & the inner surface of the tube, Rf,in as fouling resistance that occurs on the internal surface of the tube, Rcond as resistance to conduction through tube wall, Rout as resistance between the air and the surface of the fins and the outer tube surface (it is due to both convection and conduction resistance to the fin) and Rf out as fouling resistance that occurs on the outer surface of the tubes. Rin= 4.81 x 10-4 0C W-1 Rf, in = R”f, in / Atotal in © IJATER (IOCRSEM- 2014)

= 1.021x 10-4OC W-1 Rf, out = R”f, out / Atotal out = 3.3126x10-4OCW-1 We have R”f, in as fouling factor for inside, R”f, out as fouling factor for outside, Rcond = th / [ ktube x Atotal in] = 0.0163x10-4 OCW-1 Rout = 1 / ( ɳox 𝒉out x Atotal,out ) Atotal out = 6.037528 m2 ɳo = 1 –[( As fin tot / Atot)(1-ɳfin)] ɳfin= .983 ɳo = .985 Let V is velocity of air flow, ν kinematic viscosity of air, As fin total is total fin surface area, As unfin istotal unfinned surface area Re = (ρ x v x Lout ) / μ = 5.4x104 Pr = (μ x cp ) / kair = .7046 𝑵𝒖 = 0.036 x (Re)4/5 x (Pr)1/3 = 195.67 𝑵𝒖 = ( 𝒉out x Lout ) / kair ℎout = 241 W/m2K Rout = 6.977 x10-4OC W-1 Rtotal = 16.13693 x 10-4OCW-1 U A = 1 / Rtotal = .6197 x 10-3 W/ OC Therefore, the rate of heat transfer for the radiator is Q = 30984 W over total fin surface area of 5.2096 m2 and total un-finned surface area of 0.827928 m2. And the difference in heat rate, ∆Q = Qreq - Qact= 4612W

V.A. USING CARBON FOAM: Fin Material Air–water heat exchangers are commonly employed in high output internal combustion engine cooling. The resistance to convective heat transfer on the air side of the heat exchanger dominates in the design of these heat exchangers. Large numbers of metal fins are used to provide additional surface area on the air side of the heat exchanger to lower the total convective thermal resistance. These fins are generally made of aluminum having (kaluminum) of 160 - 250 W/m-K. Instead of this Porous carbon-foamwith effective (stagnant) conductivity in the range 40–180 [W/m-K] dueto the very high specific conductivity of the carbonmaterial (k = 900–1700 [W/m-K]) depending on theporosity which is normally between 0.7 and 0.9 using the current foaming process can be used to replace the aluminum fins in finned tube radiators. The unique thermodynamic properties of the foam would serve to reduce the thermal resistance of a heat exchanger. As porous carbon foam has an open, interconnected internal structure.

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International Journal of Advanced Technology & Engineering Research (IJATER) 1st International Conference on Research in Science, Engineering & Management (IOCRSEM 2014)

Rout void =1 / ( ℎout,void x As,fin,void) = .20312 x 10-4oCW-1 Rout red = 1/( ɳo red x ℎout x Atotal out red)

Fig 1 Scanning electron micrograph of the Carbon foam surface of asingle pore

Porosity = 70 % Dvoid = 350 x 10-6 m β = 9000 m2/m3 α = 0.653 pfin = 2 x 10-3 m thfin = 0.7 x 10-3 m Nfins row = 304 Rout = Rout eff

Fig 2Unit cube geometry of carbon foam

Where β is the interior surface area to volume ratio of the foam andDvoidis the void diameter of the foam.H is the dimension of the unit cube. Now, (1/ Rout eff) = (1/Rout red) + (1/Rout voids) Rout void =1 / (ℎout, voidx As,fin,void) Re =(V x Dvoid) / ν = 859.42 Pr = (μ x cp) / k = .7046 𝑁𝑢 = 1.064 x (Re).59 x (Pr)1/3 = 50.9813 𝑁𝑢 = ( ℎout void x Dvoid ) / k ℎout void = 3947.40 As fin void = β x Vol.fin total = 12.47 m2 © IJATER (IOCRSEM- 2014)

Atotal,out red = As,fin,total + As,unfin – As front void As,fin,total= 5.2096 m2 As,unfin = .827928 m2 As front void = As,fin,total x α = 3.40186 m2 Atotal,out red = 2.635668 m2 ηo red = .86 Rout red = 18.3060 x 10-4oCW-1 1/Rout eff= 1/Rout red + 1/Rout,void Rout eff= .20077 x 10-4OC W-1 Rtotal = 9.3607 x 10-4OC W-1 from equation of Rtotal UA = 1/ Rtotal = 1068.296 Therefore, rate of heat transfer from this design Q = U x A x ϴm = 53414 W Which is much greater than the required value Qreq= 35596 W. Hence, the existing radiator can be made smaller in size by 203 mm (33 %) in width. That’s means there is an extra availability of 1630 cm 3 space in engine compartment.

Fig 3Scanning electron micrograph of the carbon foam surface

V.B.USING NANOFLUID: Coolant Fluid design considering thermal and viscous properties is a critical aspect of cooling system optimization for a variety of applications. Nano-fluids, a two-phase mixtures composed of very fine particles in suspension in a continuous and saturated liquids (water, ethylene glycol, engine oil), may constitute a very interesting alternative for advanced cooling system. It may be possible that important heat transfer enhancement may be achieved while using Nano-fluids compared to the use of conventional fluids. Considering heat performance of water based Nanofluids, Al2O3 with 47 nm particle-sizes, in a conventional car radiator based upon the constraint defined earlier.

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International Journal of Advanced Technology & Engineering Research (IJATER) 1st International Conference on Research in Science, Engineering & Management (IOCRSEM 2014)

k =.76 W/m k μ = 4.596 x 10-3 N-s/m2 ν = 4.23 x 10-6 m2/s Cp =1.456 x 103 J/kg K There is increase in kinematic viscosity of water after other compounds are mixed as described above Re =(v x Lc) / ν= .076583 x 104 Pr = (μ x cp) / k= 9.0429 𝑵𝒖 = 3.66 + [ (0.668 (D/W) x Re x Pr) / (1 + 0.04 ( (D/W) x Re x Pr)2/3] 𝑁𝑢= 15.5573 As Vwater is 1.55 m/s, Lc = 4Ac / P is 2.09 mm (characteristic length) thus Lc / W is 3.42 mm. 𝑁𝑢 = (ℎin x Lc) / k ℎin= 5657.2 W/m2 K Rin = 1.8048 x 10-4 oCW-1 Replacing the value of Rin in equation of Rtotal Rtotal = 1.313073 x 10-3 o CW-1 UA = 1 / Rtotal = 761.572 W/oC There, rate of heat transfer for this design Q= U x A x ϴm = 38078.6 W This rate of heat transfer is greater than the Qreq (35596 W). Hence the radiator can work efficiently even when air temperature is higher as in warm summer days.

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Singh, Kirpal. Automobile Engineering (12th Edition). A.K.Jain, New Delhi, 1969 Brandon Fell, Scott Janowiak, Alexander Kazanis, Jeffrey Martinez. “High Efficiency Radiator Design for Advanced Coolant”, University of Michigan, (2007) Q. Yu, “Thermal engineering model for air–water heat exchangers made of carbon foam finned tubes”, M.E.Sc. Thesis, The University of Western Ontario, London, Canada, 2004. Q.Yu, Straatman Anthony, “Carbon-foam finned tubes in air–water heat exchangers”, The University of Western Ontario, London, Canada, The University of Ottawa, Ottawa, ON, Canada, 2005 Tata Indigo Owner’s Manual And Service Book

VI. CONCLUSION The application of carbon foam as the radiator material in the design shows an increased rate of heat transfer (Q= 53414 W) which is much greater than the required value (Qreq= 35596 W). Hence, the existing radiator can be made smaller in size by 203 mm (33 %) in width. That’s means there is an extra availability of 1630 cm3 space in engine compartment and decrease in the frontal surface area. Nanofluid, shows an increase rate of heat transfer (Q=38078 W) that is also a great way to enhanced the rate of convection between the inner walls of the tubing and the fluid, this rate of heat transfer is greater than the required value (Qreq= 35596 W) and hence the radiator can work efficiently even at higher load and speed requirement in hot climatic conditions.

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Rajput, R. K. Heat And Mass Transfer (5th Edition). S.Chand, New Delhi, 1999 Holman, J. P. Heat Transfer (5th Edition). McGraw-Hill, New York, NY, 1981 Carigan, Russell and Eichelberger, John, Automotive Technology – Heating & Airconditioning (2nd Edition). CenageYesdee, New York, 2005 Giri, N.K. Automobile Mechanics (8th Edition). Khanna Publishers, New Delhi, 2002

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