thermal analysis of shell and tube heat … thermal analysis is carried out in ansys fluent 15.0.th...

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International Journal of Mechanical Engineering and Technology (IJMET)Volume 8, Issue 5, May 2017, pp.

Available online at http://www.iaeme.com/IJME

ISSN Print: 0976-6340 and ISSN Online: 0976

© IAEME Publication

THERMAL ANALYSIS OF

HEAT

N Santhisree

Mechanical

ABSTRACT

Heat exchangers are devices that facilitate the heat

that are at different temperatures while keeping them from mixing with each other.

They differ from mixing chambers in that they do not allow the two fluids involved to

mix. The most common type that is used in industrial applicatio

heat exchanger. It contain a more number of tubes packed in a shell with their axes

parallel to that of the shell.

flows outside the tube through the shell and causes exchange o

fluids. To enhance heat transfer and to maintain uniform spacing between the tubes

baffles are placed in the shell to force the fluid to flow across the shell. In this present

study thermal analysis is carried out in Ansys fluent 15.0.Th

designed using CATIA V5.

Key words: Baffles, Effectiveness, Heat Transfer, heat exchanger, temperature

difference, Overall heat transfer coefficient.

Cite this Article: N Santhisree,

Shell and Tube Heat Exchanger

and Technology, 8(5), 2017

http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=8&IType=5

1. INTRODUCTION

One of the most common type of heat exchanger is shell and tube heat

used for higher pressure applications. It consists of a shell a large pressure vessel with a more

number of tubes inside it. The heat exchange takes place between the two fluids as one fluid

runs through the bundle of tubes and another

The performance and efficiency is depending upon the amount of heat transfer. Heat

exchangers are basically classified as direct contact and indirect contact. Shell and tube

exchanger is an indirect conta

front header, rear header and baffles. Enhancement of heat transfer takes place by using active

and passive methods. Active method include techniques like surface vibration injection

electrostatic fields etc. Whereas passive methods includes inserts, coiled or twisted tubes

extended surfaces, baffles etc. like mechanical modifications Baffles are provided to increase

the turbulence of the shell fluid and to direct the flow of fluid normal

IJMET/index.asp 596 [email protected]

International Journal of Mechanical Engineering and Technology (IJMET) 2017, pp. 596–606, Article ID: IJMET_08_05_066

http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=8&IType=5

6340 and ISSN Online: 0976-6359

Scopus Indexed

THERMAL ANALYSIS OF SHELL AND TUBE

HEAT EXCHANGER

N Santhisree, M Prashanthkumar , G Priyanka

Mechanical Engineering, IARE, Hyderabad, India.

eat exchangers are devices that facilitate the heat exchange between



mix. The most common type that is used in industrial applications is shell and tube

It contain a more number of tubes packed in a shell with their axes

parallel to that of the shell. One fluid of it flows through the tube and the other fluid

flows outside the tube through the shell and causes exchange of heat between the



study thermal analysis is carried out in Ansys fluent 15.0.The heat exchanger is

designed using CATIA V5.

Baffles, Effectiveness, Heat Transfer, heat exchanger, temperature

difference, Overall heat transfer coefficient.

N Santhisree, M Prashanthkumar , G Priyanka Thermal Analysis of

Shell and Tube Heat Exchanger. International Journal of Mechanical Engineering

), 2017, pp. 596–606.

com/IJMET/issues.asp?JType=IJMET&VType=8&IType=5

One of the most common type of heat exchanger is shell and tube heat exchanger. These are



runs through the bundle of tubes and another fluid flows over the tubes i.e. through the shel



exchanger is an indirect contact type heat exchanger basically consists of tube bundles, shell,



static fields etc. Whereas passive methods includes inserts, coiled or twisted tubes


the turbulence of the shell fluid and to direct the flow of fluid normal to the tubes. The space

[email protected]

T&VType=8&IType=5

SHELL AND TUBE

between two fluids



ns is shell and tube

It contain a more number of tubes packed in a shell with their axes

One fluid of it flows through the tube and the other fluid

f heat between the



e heat exchanger is

Baffles, Effectiveness, Heat Transfer, heat exchanger, temperature

M Prashanthkumar , G Priyanka Thermal Analysis of

Engineering

com/IJMET/issues.asp?JType=IJMET&VType=8&IType=5

exchanger. These are



fluid flows over the tubes i.e. through the shell.



ct type heat exchanger basically consists of tube bundles, shell,



static fields etc. Whereas passive methods includes inserts, coiled or twisted tubes[1],


to the tubes. The space

Thermal Analysis of Shell and Tube Heat Exchanger

http://www.iaeme.com/IJMET/index.asp 597 [email protected]

between the baffles as expressed as percentage of segment height to inside diameter of shell.

Segmented shell and tube heat exchanger improves heat transfer by creating turbulence. By

increasing intensity of turbulence level flow resistance can be increased and also increases

high pressure drop [3]. Which leads to increase in consumption of power. This is a major

problem. Therefore always it is desirable to select a heat exchanger with more turbulence,

high heat transfer coefficient, and low pressure drop as well as less fouling. In the present

analysis 25%cut is considered .In general it may vary from 15 to 45%.Any heat exchanger

design is based on its effectiveness and cost.

The basic flow distribution of shell and tube heat exchanger is shown below.

Figure 1 Schematic representation of shell and tube heat exchanger

2. LITERATURE REVIEW

1. Paresh Patel and Amitesh Paul Paresh Patel and Amitesh Paulhad performed thermal

analysis of tubular type heat exchanger using ANSYS and CFD analysis has been

carried out for different materials like steel, copper and aluminium and on the basis of

results obtained they have described which material gives best heat transfer rates [1].

2. Vindhya Vasiny Prasad Dubey, Raj Rajat Piyush Shanker Verma, had investigated

that the performance of a shell and tube heat exchanger depends on various factors

affect the performance of the heat exchanger and the effectiveness obtained by the

formulas depicts the cumulative effect of all the factors over the performance of the

heat exchanger [2].

3. Huadong Li and Volker Kottke et al. proposed a model to investigate local heat

transfer and pressure drop for different baffle spacing in the shell and tube heat

exchangers with segmental baffles. He analysed that for same Reynolds number, the

pressure drop and average heat transfer are increased by increase in baffle spacing [3].



4. B. Jayachandriah and K. Rajasekharmade an attempt to design a shell and tube heat

exchanger with copper and brass as tube material and steel 1008 as shell material.

From their results they have analysed the shell and tube heat exchanger by varying

tube materials and declared that they are highly efficient when they are used for liquid

to liquid applications [4].

5. S. Noie Baghban, M. Moghiman and E. Salehiperformed thermal analysis of shell side

flow of shell and tube heat exchanger with different baffle spacing’s and different

baffle cut. A shell-and-tube heat exchanger of gas-liquid chemical reactor system has

been used in the experimental method. The experimental and numerical result shows

good agreement [5].

6. Usman Ur Rehmanperformed a CFD analysis of shell and tube heat exchanger with

respect to heat transfer coefficient and pressure drop. He found that in parallel flow the

outlet temperature of fluid outside tubes is more than the outlet temperature of tube

side fluid and compared experimental results with numerical values. With the

comparing it is found that the design has to be modified.[6]

3. MATHEMATICAL MODELLING

By using Kerns method preliminary design of shell and tube heat exchangers is done. It

provide conservative results. The steps of mathematical design is as follows.

Consider energy balance to find out unknown values of temperatures. Consider some

input parameters like inlet temperature of hot fluid and cold fluid and velocity flow rates. The

fluid properties at particular temperatures etc.

The energy balance equation is given as

Q = �ℎ C�ℎ (�ℎ1-�ℎ2) = �� C�c (��2-��1)

Calculate area of tube and shell side.

Mathematical modelling involves calculating unknown temperatures by using input

parameters.

The detailed procedure is given below.

3.1 Input Data

Inlet temperature of hot fluid Th1=900C

Inlet temperature of cold fluid Tc1=70C

Specific heat of hot fluid Cph=4.205 KJ/Kg K

Specific heat of cold fluid Cpc=4.190 KJ/Kg K

Density of hot fluid ρh=967.5Kg/m3



Density of cold fluid ρc=1001.3Kg/m3

Thermal conductivity of water Kt= 0.61W/m K

Thermal Conductivity of Copper Ks= 386W/m K

Tube side fluid velocity vh = 0.1m/s

Shell side fluid velocity vc = 0.5m/s

µh = dynamic viscosity of hot fluid = 0.315*10-3

Ns/m2

µc = dynamic viscosity of cold fluid = 1.2797*10-3

Ns/m2

Tube side mass flow rate mh=ρhAtvh = 0.00309kg/s per tube

Shell side mass flow rate mc= ρcAsvc =0.6167kg/s

Reynolds Number:

For tube side: Ret = 4mh / πdiµh= 6244.93

For Shell side: Res = 4mc / πDiµc= 15339.66

Nusselt number:

Nut= 0.023*Re0.8

*Pr0.4

= 1.544

Heat transfer Coefficient in tube and shell

ht= Nut*(Kt/dt) = 51.870 w/m2 k

hs = (0.36*ks/De)* Res0.55

*Pr0.33

= 3420.044 w/m2 k

Overall Heat Transfer Coefficient U

U=1/ (1/hi*(ro/ri) + 1/ho + ((ro/k)*ln(ro/ri))) = 42.027

Using NTU Method:

Ch = mhCph = 0.6798*4.205 = 2.858 Kw/0C

Cc = mcCpc = 0.6167*4.190 = 2.583 Kw/0C

Heat capacity Ratio R=Cmin/Cmax = 2.583/2.858 = 0.903

Number of Transfer Units

NTU = UAs/Cmin

=42.027 * 0.0572 /2.583=0.930

Using R and NTU values, from graphs

Effectiveness ∈= 0.46

But ∈ = Qactual / Qmaximum



= mh Cph (Th1-Th2) / Cmin (Th1- Tc1)

0.46= 0.6798*4.205*(90-Th2) / 2.583*(90-7)

Th2 = 55.60C

Qactual = 0.6798*4.205*(90-54.5)

= 98.90 KW

But heat lost by hot fluid=heat gain by cold fluid

Which gives Tc2=45.40C

Number of tubes

Area As = n*π*(do2/4)

n = A/ π* (do2/4) n = 21.96

So No of tubes =22.

4. DESIGN OF SHELL AND TUBE HEAT EXCHANGER

By using the data obtained the shell and tube heat exchanger components have been designed

using CATIA V5.

The simulated Shell and Tube Heat exchanger has 4 baffles with 25% cut in the shell side

direction with total number of tubes 22. The whole computation domain is bounded by the

inner side of the shell and everything in the shell contained in the domain. The inlet and outlet

of the domain are connected with the corresponding tubes. To simplify simulation, some basic

assumption are made.

1. The shell side fluid is constant thermal properties

2. The fluid flow and heat transfer processes are turbulent and in steady state

3. The leak flows between tube and baffle and that between baffles and shell are neglected

4. The natural convection induced by the fluid density variation is neglected

5. The tube wall temperature kept constant in the whole shell side

6. The heat exchanger is well insulated hence the heat loss to the environment is totally

neglected.

4.1 Design

The components that are designed for shell and tube heat exchanger are

• Tubes

• Tube sheets

• Shell

• Baffles

• Tube side channels nozzles


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Figure 2 Tubes

Figure 4 Shell

Fig

The model is designed according to TEMA (Tubular Exchanger Manufacturers Association)

Figure


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Figure 3

Figure 5 Baffles

Figure 6 Tube side Channels and Nozzles


7 Shell and Tube Heat Exchanger Assembly

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3 Tube sheets

Baffles




4.2 Mesh Generation

A fine mesh is generated with 1597095 nodes.

Figure 8 Mesh generation

4.3 Thermal Simulation

Simulation is carried out as pressure based under steady state condition. . Liquid water as

fluid in tubes, copper [1] as tube material and steel as shell material. A shell and tube heat

exchanger has one inlet and outlet for tube and shell. Viscous k-€ model has been

implemented for general CFD codes. This is considered as standard industry model.

4.4 Boundary Conditions

The inlets were defined as velocity inlets and outlets were defined as pressure outlets, inlet

velocity profile assumed, , slip condition assigned to all surfaces, gauge pressure assigned to

the outlet nozzle, heat flux boundary condition assigned to the shell outer wall (excluding the

baffle shell interfaces), assuming that the shell is perfectly insulated. The surrounding air

temperature was kept 270C

Table 1 Boundary conditions applied while doing analysis

Quantity used in CFD condition/value

Tube inlet temperature 900C

shell inlet temperature 70C

Tube side velocity 0.1m/s

shell side velocity 0.5m/s

Gauge pressure zero Pascal’s

velocity profile uniform velocity

slip No slip

heat flux 0 w/m2k

4.5 Solution

The meshed component is kept for run to calculate the output parameters till the convergence

is reached by giving more number of iterations with step size. The convergence criteria were

set to 10-4

for the three velocity components and continuity, 10-7

for energy and 10-4

for

turbulent kinetic energy and dissipation energy.



5. RESULTS AND DISCUSSIONS

Various contours were plotted and different parameters were calculated such as weighted

average of total temperatures at out let and inner wall, total wall flux, pressure drop across the

hot fluid inlet and outlet to calculate pumping power.

5.1 Variation of Temperature

The temperature contour plots across the cross section of heat exchanger with and without

baffles

Figure 9 Temperature Variations in tubes without Baffles

Figure 10 Temperature Variations in tubes with Baffles

Figure 11 Cold Temperature variation in shell with baffles



5.2 Variation of Velocity

Figure 12 Variation of Velocity in Tubes without baffles

Figure 13 Variation of Velocity with baffles

Figure 14 Variation of velocity in shell with baffles

5.3 Variation of Pressure

Figure 15 Variation of Pressure without baffles



Figure 16 Variation of pressure with baffles

Figure 17 Variation of Pressure in shell with baffles

5.4 Discussions

The outlet temperature of tube and shell side fluids have been analysed with baffles and

without baffles. The effectiveness is also calculated. Heat transfer and flow distribution is

discussed in detail and the results obtained are tabulated as below.

Table 2 Results obtained in simulation

Tube side

outlet

temp(0C)

Shell side

outlet

temp(0C)

Velocity

drop(m/s)

Pressure

drop(K Pa)

Heat Transfer

Rate(KW)

WITH BAFFLES 67 27 0.02 0.3 65.74

WITHOUT

BAFFLES 70 40 0.05 1.8 54.31

6. CONCLUSIONS

• The analysis is carried out by using water as fluid and results are compared with baffles

and without baffles.

• The model predicts the heat transfer and pressure drop with an error of 25%. Thus the

model can be improved.

• The outlet temperatures of hot and cold fluids are 670C and 270C respectively with baffles

of 25% cut and 700C and 400C respectively.

7. FUTURE SCOPE

• The analysis is carried out by using water as fluid and results are compared with baffles

and without baffles.

• The analysis can also be carried out by using different working fluids like Nanofluids.



• The tubes shell and baffle can also made with different materials like galvanized steel,

aluminium etc. and the results can be compared.

• The effective performance of shell and tube heat exchanger is increased by adding fins,

inserts, coils etc.

REFERENCES

[1] Paresh Patel, Amitesh Paul “Thermal Analysis Of Tubular Heat Exchanger By Using

Ansys”, International Journal of Engineering Research & Technology (IJERT); ISSN:

2278-0181 Vol. 1 Issue 8, October – 2012.

[2] Vindhya Vasiny Prasad Dubey, Raj Rajat Verma, Piyush Shanker Verma, A.K.Srivastava

“Performance Analysis of Shell & Tube Type Heat Exchanger under the Effect of Varied

Operating Conditions” IOSR Journal of Mechanical and Civil Engineering Volume 11,

Issue 3 Ver. VI (May-Jun. 2014), PP 08-17.

[3] Huadong Li, Volker Kottke,” Effect Of Baffle Spacing On Pressure Drop And Local Heat

Transfer In Shell-And-Tube Heat Exchangers For Staggered Tube Arrangement”,

International Journal of Heat Mass Transfer, Elsevier Science, Germany, 1998.

[4] B.Jayachandriah1, K. Rajasekhar “Thermal Analysis of Tubular Heat Exchangers Using

ANSYS” International Journal of Engineering Research Volume No.3 Issue No: Special

1, pp. 21- 25 March 2014.

[5] E. Salehi, S. Noie Baghban and M. Moghiman, “Thermal analysis of shell-side flow of

shell-and tube heat exchanger using experimental and theoretical methods”, International

Journal of Engineering, Vol. No. 13, pp. 13-26, February 2000.

[6] Uttam Roy and Mrinmoy Majumder. Estimation and Analysis of Cycle Efficiency for

Shell and Tube Heat Exchanger by Genetic Algorithm. International Journal of

Mechanical Engineering and Technology, 8(2), 2017, pp. 93–101.

[7] Sunil Jamra, Pravin Kumar Singh and Pankaj Dube. Experimental Analysis of Heat

Transfer Enhancement in Circular Double Tube Heat Exchanger using Inserts.

International Journal of Mechanical Engineering and Technology, 3(3), 2012, pp. 306–

314.

[8] S. Bhanuteja and D.Azad Thermal Performance and Flow Analysis of Nanofluids in A

Shell and Tube Heat Exchanger. International Journal of Mechanical Engineering and

Technology, 4(5), 2013, pp. 164–172.

[9] Usman Ur Rehman, Heat Transfer Optimization of Shell-And-Tube Heat Exchanger

through CFD Studies, Chalmers University of Technology, 2011.

[10] LearnCAX.ORG.

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