enhancement of heat transfer through finsusing …ic engine fins assemblies with in a reacting power...

INTERNATIONAL JOURNAL OF RESEARCH IN AERONAUTICAL AND MECHANICAL ENGINEERING

WWW.IJRAME.COM ISSN (ONLINE): 2321-3051

Emerging Trends in Mechanical Engineering Proceedings of the

International Conference, ETME-2017, 27 & 28 December, 2017, Pg: -40-56

D.K. Ramesha

- 40 -

ENHANCEMENT OF HEAT TRANSFER THROUGH

FINSUSING RADIAL HOLES AND FRACTAL LIKE

GEOMETRY [1]

D.K. Ramesha[2]

AbrarAhmedKhan [2]

VrushabhendraKumar

[2]YashRajeevan

[2]Yashas NJ

[1]Associate Professor, Department of mechanical Engineering, University Visvesvaraya College of Engineering, Bangalore University, Bengaluru-560001, India

[2]UG Scholar, University Visvesvaraya College of Engineering, Bangalore University, K R

Circle, Bengaluru-560001, India [1][email protected],in[2][email protected][2][email protected][2]abukhan9136

@gmail.com

ABSTRACT

Heat transfer is a process variant in most heat generation methods, applying two wheeler heat conduction fins. IC engine fins Assemblies with in a reacting power transmission Mechanisms in this engine Assembly, which requires heat removal to ensure proper operation. The Engine fin design is highly limited by the designing of the system. But still certain parameters and geometry could be modified for better heat transfer rate from engine block. . This research focuses on increasing the life time of engine by increasing heat transfer rate from engine block to fin in such a way newly designed of Fin (increased area) that would provide better Heat transfer rate by modification of fin structure and fin geometry. The geometry are created with different thickness of fins and also by using radial holes on these fins to improve the uniform heat

transfer rate, the simulating of fin under varying climatic condition. Steady state heat transfer analyses are performed using ANSYS Workbench™ Version 16, utilizing 3D models and heat transfer material properties of current engine fins Assemblies. ANSYS results from modified fins Assembly designs are compared to baseline geometry ANSYS results. This paper is about analyzing the cylinder fins using the material Aluminum alloy 6061.

Keywords: Fractal fins, radial holes, iterations, effectiveness, natural convection

1. INTRODUCTION

An engine is a staple of modern life, a piece of engineering genius and one of the most amazing machines we use on a daily basis. An engine is a mechanically designed machine to convert one

form of energy into mechanical energy by consuming fuel and changing chemical composition.

The internal combustion engine is a engine in which the burning of fuel occurs in a confined space

mailto:[email protected],in

mailto:[email protected]








D.K. Ramesha

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called a combustion chamber. This exothermic reaction of a fuel with an oxidizer creates gases of

high temperature and pressure, which are permitted to expand. This force moves the component

over a distance, generating useful mechanical energy[1].

Heat energy that is generated by the combustion of fuel in the engine cylinder is not converted into

useful power at the crankshaft. The temperature of the gases produced by combustion will be

around 500-2300oC. This high temperature results in burning of oil film between the moving parts

and may result into seizing of engine. It’s also observed that some part of heat is transferred to

cylinder walls and if this heat is not dissipated from the cylinder it would result in pre ignition of

charge. This is where the application of fins comes to use.Fins are the extended surface of the

engine that are used to increase the rate of heat transfer[2].

The amount of conduction, convection, or radiation of an object determines the amount of heat it

transfers. Fins can enhance the heat rejection rate in engine cylinder by increasing its surface area.

The present investigation work aims to investigate heat dissipative effect of fins by modifying its

geometry[3].

2. METHODOLOGY

The base engine considered for our project was Honda Unicorn (149cc). The base engine cylinder

block with fins was made using CATIA V5. This model was then analyzed in ANSYS 16.0 in

steady state thermal analysis workbench with suitable boundary conditions.Steady State Thermal

Analysis: A steady state thermal analysis calculates the effect of steady thermal load on a system

or component, analyst were also doing the steady state analysis before performing the transient

analysis. A steady state analysis can be the last step of transient thermal analysis. We can use

steady state thermal analysis to determine temperature, thermal gradient, heat flow rates and heat

flux in an object that do not vary with time. Iterations were done in the fins using CATIA V5 and

then again analyzed in ANSYS 16.0. These iterations were compared and the results were

tabulated accordingly.The following procedures were carried out in ANSYS 16.0 (Steady state

thermal)

MESHING: The model was meshed using fine mesh.

After meshing the different boundary conditions are applied such as the inlet wall

temperature of the cylinder and the convection coefficient of the fin with the surrounding

air. The ambient temperature is assumed to be constant. The boundary conditions are

tabulated in Table 1.

https://en.wikipedia.org/wiki/Heat_conduction

https://en.wikipedia.org/wiki/Convection

https://en.wikipedia.org/wiki/Radiation





D.K. Ramesha

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Table 1: Boundary conditions applied for the models considered

Sr. No. Loads Units Value

1 Inlet temperature C 200

2 Film Coefficient W/m2K 23.5

3 Ambient temperature C 22

3. DESIGN AND MODELLING

The base model which is considered for the analysis is Honda unicorn engine. The engine is modeled using CATIA V5. It is a 4 stroke 149cc engine with 12.73 bhp power. The specification

of the engine is tabulated in Table 2.





D.K. Ramesha

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Table 2: Specifications of Honda Unicorn Engine Table 3: Specifications of Fins

The base model is provided with 9 annular fins of 2mm thickness. This fin is considered as the

base fin with no iterations or holes. The base fin is tabulated in table 3.

The models are modeled in CATIA V5 in part and assembly design. The base model is shown in

Fig 1. It consists of 9 fins of 2mm thickness and fin height of 15cm. Fig 2 shows fins provided

with radial holes. The radial holesare of diameter 1.5mmand 15cm long. There are 8 holes in one

fin i.e. total of 72 holes in the whole model.





D.K. Ramesha

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The next model is of fractal like geometry. Fig 3 shows the 1st iteration of the base model. The 1st

iteration consists of 8 holes of diameter 3mm each of length equal to the thickness of the fin i.e.

2mm. there are 72 holes in the whole model which removes the surface area and adds lateral

surface area. Fig 4 shows the 2nd

iteration of the base model. In this model, 8 holes of diameter

1.5mm is provided around the 1st iteration holes and with length equal to the thickness of the fin

i.e. 2mm. There are 64 holes of diameter 1.5mm in one fin. Hence there are 576 holes in total

which adds more lateral surface area.

These were modeled in CATIA V5 and then exported to ANSYS 16.0 under steady state thermal workbench. The material used is Aluminium 6061. Aluminium 6061 is taken as the material of the

fin because it has a higher thermal conductivity of 167 W/m2. The density of the fin is only 2.70

g/cm3. The composition of Al 6061 is tabulated in Table 4.1.





D.K. Ramesha

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Table 4.1: Composition of Aluminium 6061 Table 4.2: Aluminium 6061 properties:

4. RESULTS AND DISCUSSION

The models are transferred to ANSYS 16.0 workbench and the models were fine meshed and the

boundary conditions from TABLE 1 are applied and the temperature distribution and the heat flux

distribution along the fin is obtained.

Two methods are performed to analyze the heat flux distribution, i.e. Computational method and

analytical method to verify computational method.





D.K. Ramesha

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4.1 Computational Method

From Fig 5 it can be seen that the temperature difference of the base fin model is found to be

4.01oC. The temperature distribution is shown in Fig 5. The maximum temperature is found inside

the cylinder i.e. 200oC and the minimum temperature is found to be 195.99oC near the fin tips. The

heat flux distribution is shown in Fig 6 with maximum heat flux of 1.6364e5 W/m2 and minimum

heat flux of 250.9W/m2. The heat transfer is from the base of the cylinder or the inlet to the fin tips





D.K. Ramesha

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Fig 7 shows the temperature distribution of the fins with radial holes. The maximum temperature is found inside the cylinder wall with a temperature of 200oC and the minimum temperature is

found at the tip of the fins with a temperature of 195.78oC. The difference in temperature is found

to be 4.22oC. Fig 8 shows the heat flux distribution of the fins with radial holes. The maximum

heat flux is found to be 2.6495e5W/m2and the minimum heat flux is found to be 3959.7W/m2. The

heat transfer is observed from the base of the cylinder to the fin tip.





D.K. Ramesha

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Fig 9 shows the temperature distribution of 1st iteration fin as shown. It has a maximum temperature at the cylinder wall with a temperature of 200oC and a minimum temperature of

195.84oC.the difference in temperature is 4.16oC. It is found that 1st iteration has less temperature

difference as compared to the fins with radial holes which had a temperature difference of 4.22oC.

Fig 10 shows the heat flux distribution of 1st iteration model.

The maximum heat flux is found to be 1.6638e5W/m2and minimum heat flux of 272.68W/m2.

Again 1st iteration model has heat flux less as compared to the fins with radial holes.





D.K. Ramesha

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Fig 11 shows the temperature distribution of 2nd iteration fin as shown. It has a maximum

temperature at the cylinder wall with a temperature of 200oC and a minimum temperature of

195.30oC.the difference in temperature is 4.70oC. It is found that 2nd iteration has the maximum

temperature difference among the four models.

The maximum heat flux is found to be 1.7305e5W/m2and minimum heat flux of 162.45W/m2. 2nd

iteration has heat flux less than the fins with radial holes but is more than the 1st iteration model

and the base model. The heat transfer is again from the base of the cylinder to the fin tips.

The results are tabulated in TABLE 5 of the four models i.e. Base model, fins with radial holes, 1st

iteration model, 2nd iteration models. From the tabulated values the temperature difference is least

for the base model as compared to the other models. The maximum temperature difference is for

the 2nd iterated model (4.70oC), as the iteration has increased the surface area of the fin has

increased subsequently. Fins with radial holes are next in the list with a temperature difference of





D.K. Ramesha

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4.22oC. There are 8 radial holes of diameter 2 mm each and these radial holes increases lateral

surface area of the fins which accounts for a better temperature difference.

Table 5: Temperature and heat flux results of the four models

The heat flux is maximum for fins with radial holes ie134454.85 W/m2(avg) and least for the

baseline model ie81945.45 W/m2.(avg).

4.2 Analytical Method

The second method is analytic method which uses heat transfer equation to get the desired results.

In this method the heat transfer rate and fin effectiveness is calculated. Analytic method is used to

verify the results obtained in ANSYS 16.0. Heat transfer rate is given by,

Qfin = η*h*a*θ --------------- (1)

η= efficiency

h= convective heat transfer coefficient, W/m2K

a= area of the fin, m2

θ= temperature difference ( Tb-T∞), oC

The efficiency of the fins is calculated using

equation (2). This calculated efficiency is used in

equation (1) to calculate the heat transfer through

one fin.

The convective coefficient is calculated using a wind

velocity of 10m/s and ambient temperature of 22oC.

The area of the fin is also calculated and is tabulated

in Table 6.





D.K. Ramesha

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Base model

η, Efficiency =

=.987

h = 23.5 W/m2K

a = 7.63 x 10-3 m 2

θ = ( Tb-T∞) = (200-22) = 178 oC

henceQfin =.987 x 23.5 x 7.63 x 10-3 x 178

= 31.5013W (one fin)

= 283.509W (9 fin)

Table 6: Analytical calculated values of heat transfer and total area of fins.

As the heat transfer rate increases from base model to radial holes as found in the computational

analysis.

Hence, the ANSYS 16.0 results are validated with the analytical calculations.

Model Area x 10-3

,m2 Q (Heat Transfer Rate), W

BASE MODEL 7.63 283.509

1ST ITERATION 7.67 288.75

2ND ITERATION 8.039 302.64

RADIAL HOLES 13.27 499.57

Heat transfer through one fin is calculated

using equation (1) and the total heat

transfer for the 9 fins is calculated by

multiplying heat transfer through one fin

times 9.





D.K. Ramesha

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Fig 13 shows the variation of heat transfer rate with area of each fin and its seen that fins with

radial holes have maximum heat transfer rate. It is clear that the heat flux increases for the

subsequent models. This increase in heat transfer is due to the increase in surface area in each

iteration. The fins with radial holes have the largest surface area as compared to the other models

and hence have the maximum surface area among the four. Radial holes add lateral surface area of

length equal to the height of the fin i.e. 15cm and remove only a small area of diameter 1.5mm.

Similarly, with 1st iteration 8 holes of diameter 3mm gets removed but it adds lateral surface area

of 8 holes of diameter 3mm and thickness equal to fin thickness i.e. 2mm. hence the effect of

surface area removal is small compared to the lateral surface area addition and the total surface area increases. With 2nd iteration 64 holes are again added with 1.5mm diameter and thickness

2mm and again the total surface area increases, hence heat transfer rate increases.

The effectiveness of the fin is also calculated analytically to find the performance of the fin in

engine. Effectiveness is calculated using basic heat transfer equations.

Fig 13: Graph showing the variation of heat transfer rate with corresponding models.

Effectiveness is given by,





D.K. Ramesha

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Effectiveness is the ratio of the heat transfer from the fin surface to heat transfer when no fin is

considered. Heat transfer of no fin is calculated using equation (3). The area considered here is the

lateral surface area of the cylinder or the surface exposed to the surrounding when no fin is

considered.

Qnofin= h*anofin*θ ---------------- (3)

= 23.5*((2π*0.03*0.057)-

(2π*0.03*0.002*9))*178

= 30.7506 W

Qfin = h*afin*θ ------------------ (4)

= 9 * 23.5 * 7.63 * 10-3 * 178

= 287.24 W

€ (Base model)=287.24/30.7506 = 9.34

Table 7: Analytically calculated values of fin effectiveness.

Model Effectiveness

Base Model 9.34

1ST

Iteration 9.40

2nd

Iteration 9.84

Radial Holes 16.25

The variation of fin effectiveness and the models are shown in Fig 14. From this curve it is clear

that the fin effectiveness is maximum for the fins with radial holes and least for the base model.

This is due to the fact that, effectiveness is the ratio of heat transfer from the fin to heat transfer without any fins. This basically means it is the ratio of the area of the fin to the area without any

fins.

The fins with radial holes have the maximum surface area of 7.63 x 10-2 m2. And the area of the

unfined surface remains the same for all the four models. Hence among the four models it is





D.K. Ramesha

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clearly seen from Table 6 that the area of fins with radial holes has the maximum surface area and

the base model having the least surface area.

In fractal like geometry the effectiveness increases with each iteration, hence the performance of

the fins. There is a subsequent increase in effectiveness from one iteration to the other iteration.

Hence we can say that with each iteration the surface area of the will increase and hence its

effectiveness and heat transfer rate.

Fig 14: Graph showing the variation of fin effectiveness with the models considered.





D.K. Ramesha

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5. CONCLUSION

This work uses the radial holes and fractal geometries to enhance fin performance through an

analytical and computational study for natural convection. We have considered annular fins with

radial holes and fractal-like geometry for the baseline and first two iterations for this study. The

conclusions of the experimental study can be summarized. In fractal geometry with each iteration

the temperature difference was increased and its heat transfer rate. Heat flux rate was proportional

to the total surface area for considered pattern. Fin effectiveness was found to increase with

iteration, which increased up to 100% after two iterations. Fins with radial holes have the

maximum effectiveness and hence it has better heat transfer rate. With 8 radial holes of 1.5mm

diameter the lateral surface area of the fin increases and hence its heat transfer rate.

REFERENCES

[1] "Engine". Collins English Dictionary. Retrieved 2012-09-03.

[2] Çengel, Yunus (2003). Heat Transfer: A practical approach (2nd ed.). Boston: McGraw-Hill. ISBN 978-0-07-245893-0.

[3] "Radiator Fin Machine or Machinery". Fin Tool International. Retrieved 2006-09-18. [4] M Nectar Ozisik, “Heat Transfer a Basic Approach” ,pp. 5-6 [5] Daniel Dannelley Dr. John Baker, Committee Chair Dr. K. Clark Midkiff Dr. Paul S. Ray Dr. Robert P. Taylor Dr. Keith A. Woodbury, “Enhancement of extended surface heat transfer using fractal-like geometries.

[6] Fractals: Useful Beauty (General Introduction to Fractal Geometry). http://www.fractal.org/Bewustzijns-Besturings-Model/Fractals-Useful-Beauty [7] Baliarda, C.P., Romeu, J., and Cardama, A., 2000, "The Koch Monopole: A Small Fractal Antenna," IEEE Transactions on Antennas and Propagation, 48(11), PP. 1773-1781.

[8] Specifications of Honda Unicorn Enginehttps://honda2wheelersindia.com/unicorn/specifications/ [9] Application of Bessel Equation Heat Transfer in a Circular Finhttps://personal.egr.uri.edu/sadd/mce372/Bessel%20Application

http://www.collinsdictionary.com/dictionary/english/Engine

https://books.google.com/books?id=nrbfpSZTwskC

https://en.wikipedia.org/wiki/International_Standard_Book_Number

https://en.wikipedia.org/wiki/Special:BookSources/978-0-07-245893-0

https://en.wikipedia.org/wiki/Special:BookSources/978-0-07-245893-0

http://www.fintool.com/

http://www.fractal.org/Bewustzijns-Besturings-Model/Fractals-Useful-Beauty

http://www.fractal.org/Bewustzijns-Besturings-Model/Fractals-Useful-Beauty

https://honda2wheelersindia.com/unicorn/specifications/

https://personal.egr.uri.edu/sadd/mce372/Bessel%20Application





D.K. Ramesha

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[10] ShilpaTripathi, “Effect of Geometrical Parameters on Heat Transfer Performance of Rectangular

Circumferential Fins”, International Journal of Innovative Research and Review, Department of Chemical Engineering Volume 3, January- March 2015, PP 37-50. [11] Computational Fluid Dynamics - The Basics with Applications by John D. Anderson Jr. [12] Sara, O.N., Pekdemir, T., Yapici, S., Yilmaz, M., 2001, "Heat-transfer Enhancement in a Channel Flow with Perforated Rectangular Blocks," International Journal of Heat and Fluid Flow, 22(5), PP. 509-518. [14] Mohsin A. Ali and Prof. (Dr.) S.M Kherde, Design Modification and Analysis of Two Wheeler Engine

Cooling Fins by CFD, International Journal of Science, Engineering and Technology Research (IJSETR), Volume 4, Issue 2, February 2015. [15] Adrover, A., 2010, "Laminar Convective Heat Transfer across Fractal Boundaries," Europhysics Letters, 90(1), PP.14002-P1-14002-P6

enhancement of heat transfer through finsusing …ic engine fins assemblies with in a reacting power...

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