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30120140504017
30120140504017
30120140504017
30120140504017
30120140504017
30120140504017
30120140504017
30120140504017
30120140504017
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30120140504017

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  • 1. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 4, April (2014), pp. 138-146 © IAEME 138 DESIGN AND ANALYSIS OF AN AIR COOLED RADIATOR FOR DIESEL ENGINE WITH HYDROSTATIC TRANSMISSION FOR A SPECIAL PURPOSE VEHICLE Chavan DK1 , Maheshwari Sanchit2 , Patil Gaurav2 , Sawant Ajinkya2 , Wani Paritosh2 1 Professor, Mechanical Engineering, MMCOE, Pune, Maharashtra, India 2 Graduate Engineering Student, MMCOE, Pune, Maharashtra, India ABSTRACT A Hydraulic Transmission system is a power transmission system in which the transmission of power takes place through pressurized liquid like water, oil etc. Such systems avoid mechanical linkages like gears, belts, ropes, chains etc to a great extent. The pressurized fluid is transmitted to different parts using hydraulic actuators and tubes. As the fluid power system keeps on functioning, it generates heat due to dissipation of energy generated in overcoming the viscous and frictional forces. It causes the oil temperature to increase. Excessive increase in oil temperature leads to variation in flow characteristics of oil and affects the performance of the system. It also leads to undesirable effects in oil like oxidation, sludge formation etc. Hence to limit this, temperature of oil has to be maintained more or less constant. This is done with the help of heat exchangers called as oil coolers or radiator. Keywords: Radiator, Engine, Hydrostatic Transmission, Frictional Forces, Design. 1. INTRODUCTION The core aim of this assignment is to design and develop a tailored radiator for a special purpose vehicle which runs on Hydrostatic transmission system. Unlike mechanical transmission system, this radiator would be used for cooling of hydrostatic oil. The major challenge in this development is to design an effective air cooled radiator for optimum space and weight constraints. The methodology adopted includes selection of hydraulic prime movers and hydraulic actuators. This is followed by consideration of heat loads of engine and hydrostatic transmission. Finally a customized radiator is designed to dissipate the heat generated. Workbenches like AutoCAD, CATIA, and ANSYS are used for design and analysis. INTERNATIONAL JOURNAL OF MECHANICAL ENGINEERING AND TECHNOLOGY (IJMET) ISSN 0976 – 6340 (Print) ISSN 0976 – 6359 (Online) Volume 5, Issue 4, April (2014), pp. 138-146 © IAEME: www.iaeme.com/ijmet.asp Journal Impact Factor (2014): 7.5377 (Calculated by GISI) www.jifactor.com IJMET © I A E M E
  • 2. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 4, April (2014), pp. 138-146 © IAEME 139 2. OBJECTIVE Design and develop a radiator for cooling of oil in Hydrostatic Transmission. The space constraints in the given problem are: a. Width available= 706mm b. Height available= 370mm c. Depth available= 80mm 3. HYDRAULIC TRANSMISSION SYSTEM UNDER STUDY Fig 1: Scheme of Hydraulic Transmission System Legend: • 1- Diesel engine • 2-Gear box • 3-Variable flow pump • 4-Added pump • 5-Variable displacement motor • 6-Planetary gear box • 7-wheels • 8,9- Vehicle speed controller • 10-Microcomputer 3.1 Hydraulic Oil: MIL 5606 Properties: 1. Density (ρ) = 862.037 kg/ m3 2. Specific Heat of oil, Cpo= 2.05kJ/kg o C 3. Dynamic Viscosity, µ= 8.436e-4 Nm/s
  • 3. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 4, April (2014), pp. 138-146 © IAEME 140 3.2 Engine specification • Type : CI – turbocharged after cooled Diesel engine • Cylinder Capacity : 2.8L (4 no’s) • Max Power : 96KW@3200rpm 3.3 Hydraulic components A) Hydraulic Pump • Type: Piston Cylinder Variable Displacement ( 2 Nos.) • Maximum and minimum Pump Displacement : 75 cc/rev and 18.5 cc/rev respectively B) Hydraulic Motor • Type: Piston Cylinder Variable Displacement (2 Nos.) • Maximum and minimum Pump Displacement : 350 cc/rev and 90 cc/rev respectively 4. HEAT LOAD CALCULATIONS As a thumb rule for heat exchanger sizing • heat generation rate ൌ 20% of engine power • Q ൌ 0.2 ൈ 96 • Q=19.2kW 4.1 Temperature rise Increase in oil temperature= Heat generated (KW)/(oil specific heat* mass flow rate). Increase in oil temperature =21.5⁰C It is required to dissipate this heat generated. This is accomplished by the use of coolers, which are commonly called heat exchangers. Selection of heat exchangers: Selecting a plate fin heat exchanger: these are used as gas to liquid heat exchangers when high heat transfer rates or high operating pressure are needed. 5. DESIGN Material used: Al 19000 Table 1: Material Composition Material Al Cu Mg Si Fe Mn Zn Composition 99% 0.1% 0.2% 0.5% 0.7% 0.1% 0.1% 5.1 Logarithmic Mean Temperature Difference (LMTD) tpi = 86.5o C(oil inlet temp) tpo =65o C(oil outlet temp) tsi =50o C(air inlet temp) tso=55o C(airoutlettemp) ∆ti = tpi-tso =31.5o C ∆to=tpo-tsi=15o C .. .LMTD= (∆ti - ∆to)/ln (∆ti/∆to) = 22.23o C
  • 4. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 4, April (2014), pp. 138-146 © IAEME 141 Now, Q=UAF (LMTD)...... (a) Where Total Heat Load, Q=19200 W Overall Heat Transfer Coefficient, U=600 to 800 W/m2 K (Overall heat transfer coefficient between heavy oil and air) Hence, taking the mid-range value, U= 700 W/m2 K Correction Factor F= 1 for cross flow heat exchanger. Substituting these values in equation (a), Heat transfer area, A=1.23 m2 To find mass flow rate of air: By energy balance equation, maCpa ∆Ta=moCpo ∆To Mass flow rate of oil, mo = 30 lpm = ((30e-3)861.66)/60 = 0.430 kg/s Specific Heat of oil, Cpo= 2.05kJ/kg o C Change in temperature of oil, ∆To =21.5o C Change in temperature of air, ∆Ta =5o C (assumed) Specific Heat of air, Cpa = 1.005 kJ/kg o C .. .Mass flow rate of air, ma= 3.82 kg/s 5.2 Tube Dimensions From Aluminium tube standards Standard pipe Dia(OD)= 33.4mm(D) Wall thickness= 3.3mm Thus inner dia= OD- (2wall thickness)=33.4-(2*3.3) d=26.66mm Surface Area = 1.23m2 A= πDL 1.23= π x 33.4e-3 x L Thus L=11.72m Flow area A = (π/4) (Di) 2 =5.58e-4 m2 mo= ρAV 0.43 = 860.83 x 5.58e-4 x V .. . V= 0.895 m/s.....Oil flow velocity Reynold’s Number Re= (ρVD)/µ Re= 24357.17 .. . Re > 4000 .. . Flow is turbulent. Thus selecting pipe of this dimension 5.3 Air Velocity to the radiator Diameter of fan =width of radiator= 0.370m Density of air at 50o C = 1.109 kg/m3 Fan = 2 Nos. ma= (No. of fans) x (Area of one fan) x (Velocity) x (Air Density) .. . 3.82= 2 x (πx(.372 )/4) x V x 1.109 .. . V = 16.01 m/sec
  • 5. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 4, April (2014), pp. 138-146 © IAEME 142 5.4 Outer Surface temperature Prandtl Number, Pr= µCp/ K Pr = (8.436e-4 x 2050)/ (0.10644) = 16.24 Now, to find Nusselt Number, we use Dittus- Boelter co-relation: Nu= 0.023 x Re0.8 x Prn Nu = (0.023) x (24357.17)0.8 x (16.24)0.3 Nu = 171.47 (Here n=0.3 since fluid is being cooled) But Nu= hi/k 171.47= (hi x (26.66e-3))/ (0.10644) hi=684.59 W/m2 k This is the oil side heat transfer coefficient. To find outer surface temperature of tubes, Q = hi x A x ∆T =hi x π x D x L x [Ts-(Tpi+Tpo)/2] Ts1 = 96.96o C (Inner wall temperature) Fourier’s Law of Heat Conduction through hollow pipe Q= [2 πLK (T1-T2)]/ ln(D/d) 19200 = 2π x 12.6 x 205 x [(96.96-T2)/ln (16.7/13.3)] Ts2=96.69 o C This is outer surface temperature. 5.5 Air Side Heat Transfer coefficient Table 2: Material parameters of air at 50o C Kinematic viscosity(ν) Thermal Conductivity(k) Prandtl no.(Pr) Prandtl no(At Ts2) (Prs) 24.60 e- 6 m2 /s 28.44 e-3 W/mK 0.7029 0.697 Constants C= 0.35 (St / Sl)(1/5) = 0.35 m= 0.4. Correction factor, C2= 0.8 Diagonal Pitch,Sd = [Sl2 + (St/2) 2 ] 0.5 = 46.67 mm … (a) (St + Do)/2 = (41.75 + 33.4)/2 = 37.575 mm … (b) As (a) > (b).. . Vmax occurs in transverse plane Vmax = [St/(St-D) ] x V = 80.05 m/s Re max = (Vmax x D)/ ν = 108685.77 Nu = C2 C (Remax)m (Pr)0.36 (Pr/Prs)1/4 = 367.91 This is Zhukauskas correlation ho= ( Nu x k ) / Do = 313.27 W/m2 k.....Air side heat transfer coefficient
  • 6. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 4, April (2014), pp. 138-146 © IAEME 143 Fig 2: 2 row aligned tube arrangement 6. EXTENDED SURFACES: FINS The rate of heat transfer from solid surface to fluid is given by the equation: Q = hA (To-T∞) Where, h= Convective heat transfer coefficient, A= Surface area, (To-T∞) = Temperature difference between solid surface and fluid. In the above equation the value of ‘h’ is almost constant whenever the heat is convected to atmosphere and temperature difference cannot be controlled. Therefore, the only way is to increase the heat transfer rate, Q is by increasing the surface area A. This surface area of solid is increased by providing external surfaces called fins. 7. CAD MODEL UNDER STUDY 7.1 AutoCAD model A 2D model of radiator was developed in AutoCAD using the obtained dimensions. SL=Longitudinal Pitch ST=Transverse Pitch
  • 7. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 4, April (2014), pp. 138-146 © IAEME 144 Fig 3: 2D model of radiator 7.2 3D Model A3D model of radiator was developed in CATIA using the obtained dimensions Fig 4: 3D model of radiator
  • 8. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 4, April (2014), pp. 138-146 © IAEME 145 8. CFD ANALYSIS 3D model of radiator tubes was imported to ANSYS workbench for CFD analysis Fig 5: CAD model of radiator tube 8.1 Boundary conditions Table 3: Boundary Conditions Zone Parameter Value Inlet Mass flow inlet 0.43kg/s Temperature 360K Outlet Pressure Outlet 0 Pa Walls Heat Transfer Coefficient 313.27 W/m2 K Free stream temperature 323 K 9. RESULTS Fig 6: Temp drop through the tubes
  • 9. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 4, April (2014), pp. 138-146 © IAEME 146 Table 4: Results Parameter measured Theoretical ANSYS Temperature drop 21.5o C 23.7o C 10. CONCLUSIONS 1. Hydraulic actuators like pump and motor were selected to obtain the required tractive effort. 2. Heat load and corresponding temperature rise in oil was calculated. 3. To dissipate the rise in temperature, air cooled radiator was designed by the standard procedure of LMTD method. 4. Fins were provided to enhance the heat dissipation rate by increasing the surface area of heat transfer. 5. The design was successfully conformed to the available space. 6. Analysis of the radiator was done using CFD in ANSYS Fluent. The theoretical results and analytical results were compared to ensure a safe and reliable design 11. REFERENCES 1. Chavan D. K & Tasgaonkar G. S- Study, analysis and design of automobile radiator (heat exchanger) proposed with cad drawings and geometrical model of the fan ijmperd/vol 3/ issue 2/ june 2013. 2. Fluid Power with applications (seventh edition) by Anthony Esposito. 3. Fundamentals of Heat and Mass Transfer (fifth edition) by Frank P. Incropera and David P. DeWitt. 4. Computational Fluid Dynamics by John D. Anderson. 5. http://www.alascop.com/pdf/al/6061_pipe.pdf. 6. http://www.lindeengineering.com/internet.global.lindeengineering.global/en/images/P_3_2_e_ 12_150dpi19_5772.pdf. 7. Pundlik R. Ghodke and Dr. J. G. Suryawanshi, “Advanced Turbocharger Technologies for High Performance Diesel Engine - Passanger Vehicle Application”, International Journal of Mechanical Engineering & Technology (IJMET), Volume 3, Issue 2, 2012, pp. 620 - 632, ISSN Print: 0976 – 6340, ISSN Online: 0976 – 6359. 8. Mohd Muqeem and Dr. Manoj Kumar, “Design of an Intercooler of a Turbocharger Unit to Enhance the Volumetric Efficiency of Diesel Engine”, International Journal of Mechanical Engineering & Technology (IJMET), Volume 4, Issue 3, 2013, pp. 1 - 10, ISSN Print: 0976 – 6340, ISSN Online: 0976 – 6359.

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