Performance Improvement of Base Fluid Heat Transfer Medium Using Nano Fluid Particles

Performance Improvement of Base Fluid Heat Transfer Medium Using Nano Fluid Particles

T. Sathish

Department of Mechanical Engineering, Saveetha School of Engineering, SIMATS, Chennai, Tamil Nadu – 602 105, India

Corresponding Author Email: 
sathish.sailer@gmail.com
Page: 
235-243
|
DOI: 
https://doi.org/10.14447/jnmes.v23i4.a03
Received: 
20 July 2020
|
Revised: 
18 October 2020
|
Accepted: 
26 October 2020
|
Available online: 
31 December 2020
| Citation

© 2020 IIETA. This article is published by IIETA and is licensed under the CC BY 4.0 license (http://creativecommons.org/licenses/by/4.0/).

Abstract: 

Base fluids like water, ethylene glycolandengineoilare conventionally used as a heat transfer medium. The performance of heat transferred is improved in the conventional fluids with the addition of Nano particles. Hence, this paper considers the forced conventional flow problem over the base fluid within a uniform heated tube placed on a wall. The analysis of heattransferco-efficientis done through a constant Reynoldsnumberfor both Nano and base fluid with a simulation tool. Further, a comparative analysis is carried out with heat transfer coefficient over the base and various Nano fluids. It is seen that the Nano fluids has a better performance due to its better thermal characteristics under standard conditions.

Keywords: 

heat transfer coefficient, CFX simulation, ansys simulation, nano fluid and base fluid

1. Introduction

The Nano fluids contains fluid with Nanometer-sized particles [1], which has good stability, increased thermal conductivity even with small suspended Nanoparticles and heat transferring performance. The Nano fluidmaterials vary based on metal oxides, chemically stable metals, metal carbides, oxide ceramics etc. However, most literatures focus on single-particle based Nano fluids to test the thermal characteristics [2]. The thermal fluids like oil, water and ethylene glycol plays a major role in cooling process in many power applications. However, these fluid contains poor thermal properties and the properties of heat transfer rate is affected. Hence, to heat transfer coefficient is improved with the help of extended surface channels, surface vibration and fluid injection. The use of new technology is being an enhancing factor to improve the thermal properties of such substance [3].

The main advantage of Nano fluids include ling term stability, superior thermal conductivity and reduced drop in pressure, when compared with mm and μm sized particle. The materials like metal carbides, oxide ceramics, metals, nitrides, nonmetals, carbon Nanotubes and Nanoparticles is used to form the Nano fluid. A synthesis optimization is used to make the suspensions of Nanoparticle to be stable inside the base fluid.

In order to improve the thermal properties, several combinations of base fluid with Nano particle is possible. Also, the Nano fluids are produced using a single step or two step method, where the former one uses formation and dispersion of Nanoparticles within the base fluid, using several experimental procedures [4]. Hence, the use of storage, drying, transportation and dispersion is avoided with such method.

The solid substance possesses better thermal conductivities than other substances. Most researches concentrated on the thermal properties associated with the suspension of solid particles in conventional fluids. Such dispersed particles vary from mm to μm size over the base fluid and this leads to change in thermo-physical properties of such fluid and that results in enhancing the heat transfer ratio. The main disadvantage of such mm to μm sized particle leads to poor stability and suspension and this results in channel clogging. However, recent advances with the help of new materials improves the thermal properties of the fluid than the conventional fluids [5]. From conventional studies, it is seen than the thermal conductivity of the Nano fluids is found higher than base fluid [6-8].

Out of which, water is used as a base fluid, where a rod and spherical shaped TiO2 [9] Nanoparticles are dispersed in water. The use of aqueous/non-aqueous solution as base fluid is used with metal oxide particles of varying shapes and concentration [10]. The water is further used with Al2O3 [11, 12], Fe3O4 [13], NH3 [14], Al2O3and TiO2 [15], MgO [16], COOH [17], to measure the pH effect with varying thermal conductivity. With different fractional weights, the copper based water base fluid is used to measure the pH rate with sodium dodecyl benzene sulfonate surfactant [18]. Also, water is used with carbon Nano tubes and TiO2 [19] with carbon Nano tubes measures the time and temperature [20] variations and Nanodiamond particle with deionized fluid measures varying loads [21]. Nanoparticlesgraphene [22], Nanoshell [23], graphene oxide Nanosheets [24] and Nano diamond [25] with water as base fluids.

The use of Ethylene Glycol as base fluid is experimented in several researches, which includes: synthetic EG multiwalled carbon Nanotubes [26], ZnO-EG Nano fluids [27, 28], Al-Zn with EG Nanoparticles [29], graphene Nanosheets with EG [30], Aluminum nitride with EG Nanoparticle [31], Al2Cu and Ag2Al with EG Nanoparticles [32], Al2O3, CuO, ZnO with EG [33], TiO2Nanoparticles with EG [34], CuO Nanoparticles [35], Cu Nanoparticles [36], α-SiC Nano fluids [37], spherical ZnO Nanoparticles [38], Al2O3 with EG and water [39, 40].

The increased techniques to improve the heat transfer coefficients suffer majorly the important strategy required to achieve effective heat transfer over conventional base fluid. Hence, the heat transfer is intensified with the suspension of Nanoparticles with the use of base fluid. In the proposed work, we considered the problem of improving the heat transfer coefficient by the use of Nano fluids. Here, base fluids like engine oil, ethylene glycol and water and the Nanoparticles of gold, copper, aluminum and silver is used. Empirical relations are used to calculate the properties of the Nano fluids. Further, the thermo-physical properties of ethylene glycol, water, copper, engine oil, gold, aluminum and silver is calculated to find the Nano fluid properties. The heat transfer rate of the Nano and base fluid is analysed with the use of CFX simulation tool under a constant Reynolds number. Finally, comparative analysis is carried between the thermal conductivity models namely, Maxwell, Hamilton and Crosser, and Davis models [41, 42].

The outline of the paper is mentioned as follows: Section 2 provides the proposed model to analyse the flow rate in base and Nano fluid analysis. Section 3 provides the experimental method for finding the thermo-physical properties. Section 4 provides the evaluation on different combinations of Nano fluids with base fluid. Section 5 concludes the paper.

2. Methods

Figure 1. Experimental Setup

Figure 2. Geometry of Tube

The experimental setup of the proposed method is shown in Figure 1. The system has alooping pipeline flow structure, pumping and copper tube of length1mand diameter 60mm and are servoir tank. Further, the tube is insulated with 25mm glass made of fiber and heat electrically at 5000 W/m2. The tube is coated with nickel chrome wire, which is connected with a 300W DC supply. The tube is installed with four k type tube, where two of which is placed at two end. This is used to measure the temperature of the Nano fluid.

The numerical simulation uses single phase method to find the values of convective heat transfer. Here, the geometry of the tube is shown in Figure 2. The tube allows the Nano fluidto enter at a uniform velocity rate (U1)and the rate of temperature(T1).The condition of full development is assumed at the tube end. Based on the tube’s centerline, the assumptions are made symmetrically on thermal and velocity fields. The local heat transfer coefficient rate is hlocal:

${{h}_{local}}=\frac{\left( {{T}_{local}}-{{T}_{input}} \right)\rho CpuD}{4\pi \left( {{T}_{w}}-{{T}_{input}} \right)}$        (1)

The averagerate of heattransferco-efficient is given as have:

${{h}_{ave}}=\frac{1}{L\int_{0}^{L}{h\left( z \right)dz}}$         (2)

The Average Nusselt number is then given by:

$N{{u}_{ave}}=\frac{{{h}_{ave}}D}{{{K}_{af}}}$          (3)

Heat transfer(Q)

$Q=\sqrt{\frac{{{C}_{d}}{{a}_{1}}{{a}_{2}}\left( 2g{{h}_{a}} \right)}{\left( a_{1}^{2}-a_{2}^{2} \right)}}$       (4)

3. Estimation Thermo-Physical Properties

The measuring the thermal conductivity of the Nano fluid use heat transfer coefficient, both in forced and natural fluid flow. The main limitation involves thermal characteristics of the Nanoparticles without changing the phase. The proposed model uses two phase systems for finding the heat transfer ratio of particles in the Nano fluid. Here, the coefficient of heat transfer rate depends on thermal conductivity, density, specific heat ratio and dynamic viscosity of particles in the Nano fluid. The properties of particles in the Nano fluid at normal temperature is shown in Table 1 and the properties of base fluid at normal temperature is shown in Table 2.

Table 1. Nano particles Properties

Property

Copper

Gold

Silver

Aluminum

Thermal conductivity (KS)W/mK

401

317

429

237

Density (ρp)kg/m3

8933

19300

10500

2702

Specific heat (CP) J/kg K

385

129

235

903

Table 2. Base Fluid Properties

Property

Water

E. glycol

Engine Oil

Thermal conductivity (Kf)W/mK

0.613

0.252

0.145

Density (ρf)kg/m3

996.5

1114.4

884.1

Specific heat (Cf)J/kgK

4179

2415

1909

Dynamic viscosity (µf) Kg/ms

0.000855

0.0157

0.486

3.1. Density Estimation

 The Nanofluiddensity is calculatedwith massbalance, which is given as:

ρnf=(1-φS)ρf+φSρp               (5)

The particles present in the Nano fluid has a volume fraction < 1% and the changeof <5%fluiddensityis thus expected. Further, the density for 1% particles with copper mix and water as base fluid, the Nano fluid density is found to be 1075.865Kg/m3. From Eq. (5), the Nano fluid density for different % mixes i.e. 1,3,5,...,25, various combinations are calculated, which is shown in Table.3. The different mixture of Nano fluids include: copper as base fluid with water as Nano fluid, gold as base fluid with water as Nano fluid, silver as base fluid with water as Nano fluid, aluminum as base fluid with water as Nano fluid, copper as base fluid with ethyleneglycol as Nano fluid, gold as base fluid and ethyleneglycol as Nano fluid, silver as base fluid with ethyleneglycol as Nano fluid, aluminum as base fluid with ethyleneglycol as Nano fluid, copper as base fluid with engine oil as Nano fluid, gold as base fluid with engine oil as Nano fluid, silver as base fluid with engine oil as Nano fluid and finally aluminum as base fluid with engine oil as Nano fluid. The density of these base fluid and Nano fluid mixtures are shown in Table 3.

Table 3. Various Nano fluid Density (in Kg/m3)with different base fluid combinations

 

Volume fraction (%)

copper-

water

gold-

water

silver-water

aluminum -

water

copper-Ethylene glycol

gold-Ethylene glycol

silver-Ethylene glycol

aluminum-Ethylene glycol

copper-Engine Oil

gold-Engine Oil

silver-Engine Oil

aluminum-  Engine Oil

1

1075.865

1179.535

1091.535

1013.555

1192.586

1296.256

1208.256

1130.276

964.589

1068.259

980.259

902.279

3

1234.595

1545.605

1281.605

1047.665

1348.958

1659.968

1395.968

1162.028

1125.567

1436.577

1172.577

938.637

5

1393.325

1911.675

1471.675

1081.775

1505.33

2023.68

1583.68

1193.78

1286.545

1804.895

1364.895

974.995

7

1552.055

2277.745

1661.745

1115.885

1661.702

2387.392

1771.392

1225.532

1447.523

2173.213

1557.213

1011.353

9

1710.785

2643.815

1851.815

1149.995

1818.074

2751.104

1959.104

1257.284

1608.501

2541.531

1749.531

1047.711

11

1869.515

3009.885

2041.885

1184.105

1974.446

3114.816

2146.816

1289.036

1769.479

2909.849

1941.849

1084.069

13

2028.245

3375.955

2231.955

1218.215

2130.818

3478.528

2334.528

1320.788

1930.457

3278.167

2134.167

1120.427

15

2186.975

3742.025

2422.025

1252.325

2287.19

3842.24

2522.24

1352.54

2091.435

3646.485

2326.485

1156.785

17

2345.705

4108.095

2612.095

1286.435

2443.562

4205.952

2709.952

1384.292

2252.413

4014.803

2518.803

1193.143

19

2504.435

4474.165

2802.165

1320.545

2599.934

4569.664

2897.664

1416.044

2413.391

4383.121

2711.121

1229.501

21

2663.165

4840.235

2992.235

1354.655

2756.306

4933.376

3085.376

1447.796

2574.369

4751.439

2903.439

1265.859

23

2821.895

5206.305

3182.305

1388.765

2912.678

5297.088

3273.088

1479.548

2735.347

5119.757

3095.757

1302.217

25

2980.625

5572.375

3372.375

1422.875

3069.05

5660.8

3460.8

1511.3

2896.325

5488.075

3288.075

1338.575

3.2. Specific heat estimation

The estimation of specific heat of Nano fluids with mass balance is calculated as:

(1-φS)ρfCf+φSρpCP      (6)

where, Cnf=ρnf, a small reduction over the Nano particle’s specific heat while the dispersion of solid particle in liquid is estimated using following calculations. Further, the specific heat for 1% particles with aluminum oxide mix and water as base fluid, the Nano fluid density is found to be 3863.981J/KgK. The specific heat for other Nano-fluid mixes for different percentage is shown in Table 4.

Table 4. Nano fluid Specific Heat Capacity (inJ/KgK) with different base fluid combinations

Nano particle %

copper- Water

gold-Water

silver-Water

Aluminum -Water

copper-Ethylene glycol

gold-Ethylene glycol

silver-Ethylene glycol

aluminum-Ethylene glycol

copper-  Engine Oil

gold-Engine Oil

silver-Engine Oil

aluminum-  Engine Oil

1

3863.981

3516.324

3799.608

4091.666

2262.944

2074.637

2225.553

2378.855

1767.863

1587.411

1729.69

1878.874

3

3355.447

2661.827

3209.622

3925.529

2011.711

1617.639

1923.083

2309.527

1546.146

1191.586

1459.298

1822.123

5

2962.78

2134.589

2772.032

3769.869

1812.674

1324.912

1692.316

2243.887

1379.913

957.3103

1265.104

1769.604

7

2650.429

1776.822

2434.545

3623.725

1651.097

1121.377

1510.457

2181.649

1250.653

802.4449

1118.877

1720.861

9

2396.039

1518.129

2166.337

3486.251

1517.314

971.6587

1363.448

2122.554

1147.266

692.4656

1004.798

1675.501

11

2184.847

1322.363

1948.061

3356.697

1404.722

856.9054

1242.147

2066.37

1062.69

610.3278

913.315

1633.184

13

2006.711

1169.052

1766.962

3234.398

1308.656

766.1491

1140.353

2012.888

992.2192

546.6472

838.32

1593.613

15

1854.433

1045.737

1614.287

3118.762

1225.725

692.5751

1053.71

1961.916

932.5968

495.8309

775.7238

1556.53

17

1722.763

944.3986

1483.83

3009.257

1153.408

631.7257

979.0705

1913.284

881.4968

454.3383

722.6865

1521.707

19

1607.784

859.6432

1371.071

2905.41

1089.79

580.5627

914.1013

1866.832

837.2137

419.8191

677.1738

1488.943

21

1506.511

787.708

1272.637

2806.792

1033.391

536.9437

857.0375

1822.417

798.4687

390.6516

637.6904

1458.062

23

1416.631

725.8888

1185.962

2713.019

983.0471

499.3146

806.519

1779.909

764.2841

365.6807

603.1126

1428.904

25

1336.324

672.1919

1109.057

2623.742

937.8336

466.521

761.4806

1739.187

733.8995

344.0615

572.5798

1401.331

3.3. Velocity of Nano Fluid

The input parameter for the simulation model is the velocity of Nano fluid possessing its own materialistic properties. Initially, the co-efficient for heat transfer rate is estimated for base and Nano fluid using constant Reynold number, where Re = udρ/μ = 2000.The velocity of the water is found as 0.29m/s, and for ethylene glycol =4.7m/s and engine oil is 183m/s. Further, the velocity of different Nano-fluid mixes for different percentage is shown in Table 5.

Table 5. Velocity (in m/s) of Different Nano fluid mixtures

Nano particle %

copper-Water

gold-Water

silver-Water

aluminum -Water

copper-Ethylene glycol

gold-Ethylene glycol

silver-Ethylene glycol

aluminum-Ethylene glycol

copper-Engine Oil

gold-Engine Oil

silver-Engine Oil

aluminum- Engine Oil

1

0.264903

0.241621

0.2611

0.281188

4.388223

4.037268

4.331312

4.630138

167.9472

151.6486

165.2624

179.5454

3

0.230845

0.184394

0.222377

0.272034

3.879538

3.152671

3.748892

4.503621

143.9275

112.7681

138.1572

172.5907

5

0.204547

0.149084

0.193657

0.263456

3.476536

2.586048

3.30454

4.383834

125.9186

89.75591

118.6904

166.1547

7

0.183628

0.125124

0.171506

0.255403

3.149381

2.192071

2.954362

4.270254

111.9153

74.544

104.032

160.1815

9

0.16659

0.107799

0.153903

0.247827

2.878504

1.902267

2.671289

4.162411

100.7149

63.74111

92.59624

154.6228

11

0.152446

0.094688

0.139577

0.240688

2.650533

1.680142

2.437719

4.059881

91.55237

55.67299

83.42564

149.437

13

0.140516

0.084421

0.127691

0.233949

2.456021

1.504468

2.241709

3.962281

83.91795

49.41786

75.90784

144.5877

15

0.130317

0.076162

0.11767

0.227577

2.288106

1.362053

2.074875

3.869263

77.45878

44.42634

69.63294

140.0433

17

0.121499

0.069375

0.109108

0.221542

2.141682

1.244268

1.931154

3.780513

71.92287

40.35067

64.31626

135.7758

19

0.113798

0.063699

0.101707

0.21582

2.012872

1.145234

1.806053

3.695742

67.12547

36.95997

59.75388

131.7608

21

0.107016

0.058881

0.095247

0.210386

1.898676

1.060802

1.696174

3.61469

62.92804

34.09493

55.7959

127.9763

23

0.100996

0.054741

0.089558

0.205218

1.796743

0.987964

1.598898

3.537116

59.22466

31.64213

52.32969

124.4032

25

0.095618

0.051145

0.08451

0.200299

1.705197

0.924487

1.512174

3.462802

55.93295

29.51855

49.26895

121.0242

3.4. Viscosity of Nano fluids

The Nano fluid viscosity is estimated using 2 phase mixtures,

µ=µ0(123φS2+7.3φS+1)       (7)

Further, the viscosity of 1% particles with copper mix and water as base fluid, the Nano fluid density is 0.000928kg/ms. The combination of Nano fluid with water, ethylene glycol and engine oil is estimated and shown in Table 6.

Table 6. Nano fluid Viscosity (in kg/ms) with water, ethylene glycol and engine oil

Nanoparticle

%

Nanoparticle-Water

Nanoparticle-

Ethyleneglycol

Nanoparticle-

Engineoil

1

0.000928

0.017039

0.527456

3

0.001137

0.020876

0.646234

5

0.00143

0.026258

0.812835

7

0.001807

0.033185

1.027258

9

0.002269

0.041657

1.289504

11

0.002814

0.051673

1.599572

13

0.003444

0.063235

1.957462

15

0.004157

0.076341

2.363175

17

0.004955

0.090992

2.81671

19

0.005837

0.107189

3.318068

21

0.006803

0.12493

3.867248

23

0.007854

0.144215

4.46425

25

0.008988

0.165046

5.109075

3.5. Nano fluid Thermal Conductivity

TheNano fluid contains smaller particles with high thermal conductivity than the base fluid. The thermal conductivity depends entirely on particle volume fraction for its better enhancement. The thermal conductivity of the Nano fluids are estimated using three models, which depends entirely on the particle shape:

3.5.1. Maxwell Model

This model considers the spherical Nano particle and the relation is given by,

$K={{K}_{L}}\frac{{{K}_{S}}+2{{K}_{L}}+2\left( {{K}_{S}}-{{K}_{L}} \right){{\phi }_{S}}}{{{K}_{S}}+2{{K}_{L}}-\left( {{K}_{S}}-{{K}_{L}} \right){{\phi }_{S}}}$        (8)

3.5.2. Hamilton and Crosser Model

This model considers the non-spherical Nanoparticle and the relation is given by,

$K={{K}_{L}}\frac{{{K}_{S}}+\left( n-1 \right){{K}_{L}}-\left( n-1 \right)\left( {{K}_{L}}-{{K}_{S}} \right){{\phi }_{S}}}{{{K}_{S}}+\left( n-1 \right){{K}_{f}}-\left( {{K}_{L}}-{{K}_{S}} \right){{\phi }_{S}}}$       (9)

where n totally depends on the shape of particleand KS/KL,Also,nis 3/ψ∀KS/KL>100 and the value of n is 3forothercases

3.5.3. Davis Model

This model considers the tubularNanoparticle and the relation is given by,

$K={{K}_{L}}\times 1+\frac{3\left( \frac{{{K}_{S}}}{{{K}_{L}}-1} \right)\left[ {{\phi }_{S}}+f.\phi _{S}^{2}+O\left( \phi _{S}^{3} \right) \right]}{\left( \frac{{{K}_{S}}}{{{K}_{L}}+2} \right)-\left( \frac{{{K}_{S}}}{{{K}_{L}}-1} \right){{\phi }_{S}}}\times {{K}_{L}}$      (10)

Table 7(a). Nano fluid thermal conductivity

Nano particle %

Water & Copper

Ethylene glycol & Copper

Engine oil & Copper

Maxwell

Hamilton and crosser

Davis

Maxwell

Hamilton and crosser

Davis

Maxwell

Hamilton and crosser

Davis

1

0.63149

0.619042

0.631677

0.259622

0.25449

0.259699

0.149389

0.146434

0.149433

3

0.669608

0.630775

0.671357

0.275336

0.259326

0.276057

0.158439

0.149219

0.158854

5

0.709324

0.642063

0.714381

0.291711

0.263978

0.293795

0.167869

0.151898

0.169069

7

0.750739

0.652931

0.761056

0.308788

0.268457

0.313041

0.177704

0.154476

0.180153

9

0.793966

0.663402

0.811718

0.326615

0.272771

0.333934

0.187971

0.156961

0.192186

11

0.839125

0.673497

0.866735

0.345241

0.276931

0.356625

0.198699

0.159355

0.205255

13

0.88635

0.683237

0.926505

0.364721

0.280943

0.38128

0.209919

0.161665

0.219456

15

0.935785

0.692638

0.991466

0.385116

0.284816

0.408079

0.221667

0.163895

0.234892

17

0.98759

0.70172

1.062096

0.406492

0.288556

0.437221

0.23398

0.166049

0.251678

19

1.041938

0.710498

1.138921

0.428921

0.292172

0.468923

0.246901

0.16813

0.26994

21

1.099022

0.718986

1.222521

0.452483

0.295667

0.503426

0.260474

0.170143

0.289816

23

1.159054

0.7272

1.313533

0.477266

0.29905

0.540994

0.274752

0.17209

0.311459

25

1.222269

0.735151

1.412665

0.503368

0.302324

0.58192

0.289791

0.173975

0.335038

Table 7(a). Nano fluid thermal conductivity (continued)

Nano particle %

Water & Gold

Engine oil & Gold

Ethylene glycol & Gold

Maxwell

Hamilton and crosser

Davis

Maxwell

Hamilton and crosser

Davis

Maxwell

Hamilton and crosser

Davis

1

0.631467

0.619035

0.631654

0.188879

0.146434

0.149432

0.259618

0.254489

0.259695

3

0.669538

0.630754

0.671285

0.192767

0.149218

0.15885

0.275324

0.259323

0.276045

5

0.709201

0.64203

0.714251

0.19682

0.151896

0.169062

0.29169

0.263973

0.293773

7

0.75056

0.652886

0.760863

0.201046

0.154474

0.180142

0.308758

0.268449

0.313009

9

0.793725

0.663346

0.811454

0.205458

0.156957

0.192171

0.326574

0.272762

0.333889

11

0.838817

0.673431

0.86639

0.210068

0.159352

0.205236

0.345188

0.276919

0.356567

13

0.885969

0.683161

0.926069

0.21489

0.161661

0.219431

0.364656

0.28093

0.381206

15

0.935325

0.692554

0.990926

0.219938

0.16389

0.234861

0.385038

0.284801

0.407987

17

0.987043

0.701628

1.06144

0.225229

0.166044

0.251641

0.406399

0.288541

0.437109

19

1.041297

0.710398

1.138135

0.230781

0.168125

0.269896

0.428812

0.292155

0.46879

21

1.098278

0.71888

1.221587

0.236613

0.170137

0.289764

0.452357

0.295649

0.503267

23

1.158196

0.727087

1.312432

0.242748

0.172084

0.311397

0.47712

0.299031

0.540807

25

1.221286

0.735033

1.411375

0.249209

0.173968

0.334965

0.503201

0.302304

0.581701

Table 7(b). Nano fluid thermal conductivity

Nano particle %

Water & Silver

Ethylene glycol & Silver

Engine oil & Silver

Maxwell

Hamilton and crosser

Davis

Maxwell

Hamilton and crosser

Davis

Maxwell

Hamilton and crosser

Davis

1

0.631496

0.619044

0.631682

0.259623

0.254491

0.2597

0.149389

0.146434

0.149434

3

0.669626

0.63078

0.671375

0.275339

0.259327

0.27606

0.15844

0.149219

0.158855

5

0.709354

0.642072

0.714413

0.291716

0.26398

0.293801

0.16787

0.151898

0.169071

7

0.750783

0.652943

0.761103

0.308796

0.268459

0.31305

0.177706

0.154477

0.180156

9

0.794025

0.663416

0.811784

0.326625

0.272774

0.333945

0.187974

0.156961

0.19219

11

0.839201

0.673514

0.86682

0.345253

0.276933

0.35664

0.198703

0.159356

0.20526

13

0.886444

0.683255

0.926613

0.364737

0.280946

0.381298

0.209924

0.161666

0.219462

15

0.935899

0.692659

0.991599

0.385136

0.284819

0.408101

0.221673

0.163896

0.234899

17

0.987725

0.701743

1.062257

0.406515

0.28856

0.437248

0.233988

0.16605

0.251687

19

1.042096

0.710522

1.139115

0.428948

0.292176

0.468956

0.246909

0.168132

0.269951

21

1.099206

0.719012

1.222751

0.452514

0.295672

0.503465

0.260485

0.170144

0.289829

23

1.159266

0.727227

1.313805

0.477302

0.299054

0.54104

0.274764

0.172091

0.311474

25

1.222511

0.73518

1.412984

0.503409

0.302329

0.581974

0.289804

0.173976

0.335055

Table 7(b). Nano fluid thermal conductivity (continued)

Nano particle %

Water & Aluminum

Ethylene glycol & Aluminum

Engine oil & Aluminum

Maxwell

Hamilton and crosser

Davis

Maxwell

Hamilton and crosser

Davis

Maxwell

Hamilton and crosser

Davis

1

0.631431

0.619023

0.631617

0.259612

0.254487

0.259689

0.149386

0.146433

0.14943

3

0.669424

0.630721

0.671167

0.275305

0.259317

0.276025

0.158428

0.149216

0.158843

5

0.709003

0.641976

0.714043

0.291656

0.263964

0.293738

0.167851

0.151893

0.16905

7

0.750271

0.652813

0.760553

0.308709

0.268437

0.312956

0.177677

0.15447

0.180125

9

0.793337

0.663256

0.811029

0.326508

0.272747

0.333817

0.187935

0.156952

0.192147

11

0.838323

0.673325

0.865834

0.345104

0.276901

0.356472

0.198653

0.159346

0.205204

13

0.885358

0.68304

0.925367

0.364552

0.280909

0.381086

0.209863

0.161654

0.219391

15

0.934586

0.692419

0.99006

0.384912

0.284779

0.40784

0.221599

0.163883

0.234813

17

0.986165

0.70148

1.060387

0.40625

0.288516

0.43693

0.2339

0.166035

0.251582

19

1.040267

0.710238

1.136872

0.428637

0.292128

0.468575

0.246806

0.168116

0.269825

21

1.097081

0.718709

1.220086

0.452153

0.29562

0.503012

0.260365

0.170127

0.289679

23

1.156817

0.726906

1.310663

0.476886

0.299

0.540506

0.274626

0.172073

0.311297

25

1.219707

0.734842

1.409303

0.502932

0.302272

0.581348

0.289646

0.173957

0.334848

Further, the thermal conductivity of 1% particles with copper mix and water as base fluid is 0.63149 using Maxwell model, 0.619042 suing Hamilton and crosser model, and 0.631677 using Davis model. The thermal conductivity of different Nano particle mixtures for all the three models is given in Table 7(a) and Table 7(b).

From the results, it is found that the Maxwell model provides a better results with regular variation and the mean values has better values than the other two models. Since, most of the particles in the Nano fluid possess spherical in shape.

4. Results and Discussion

This research considers the problem related to convection flow of Nano particles in a tube, which is heated uniformly. The chosen measurements for the study includes 6mm diameter and length of 170mm and the simulation analysis is carried out in Ansys Workbench tool.

The proposed tubular module is connected to a constant and uniform heat flux at the wall of the chamber. The analysis to find the heat transfer rate is analysed on base and Nano fluid with constant Reynolds number.

(a) Modeling after symmetry; (b) Modeling after meshing

Figure 3. 3D modelling of uniform heated tube

Figure 4. CFX Modelling

Table 8. Heat transfer co-efficientof Water, Ethylene glycol (E.GL) and Engine oil (E.Oil) with Nanoparticles at 333K

Nano particle %

H2O + Cu

H2O

+Au

H2O

+ Ag

H2O + Al

E.Gl + Cu

E.Gl

+ Au

E.Gl

+ Ag

CFX

Experimental

CFX

Experimental

CFX

Experimental

1

13540

13689.4

13610.8

13553.1

13493.3

13520.36

3935.24

4018.2

3963.36

3940.53

3

14533.5

14628.3

14681.2

14564.6

14412.6

14530.42

4262.92

4325.8

4351.45

4280.27

5

15542.4

15722.6

15584.3

15367.1

4613.62

4766.56

4644.98

7

16572.7

16762.8

16621

16357.2

4985.12

5204.62

5032.2

9

17629.6

17816.8

17681.4

17384.1

5376.37

5662.75

5440.7

11

18719

18894

18772

18451.3

5788.12

6140.56

5870.95

13

19846.1

20003.9

19898.5

19562.8

6222.22

6638.89

6324.61

15

21014.9

21159.9

21065.5

20722.4

6680.16

7158.86

6802.98

17

22230.6

22366.3

22278

21933.7

7163.46

7701.48

7307.41

19

23497.6

23629.5

23543.2

23200.6

7673.6

8267.87

7839.16

21

24821.8

24951.6

24869.8

24527

8212.31

8859.32

8399.79

23

26213.4

26335.6

26261.3

25918.9

8782.36

9478.35

8991.85

25

27675.5

27784.7

27725.1

27381.1

9385.15

10126.3

9616.54

Table 8. Heat transfer co-efficientof Water, Ethylene glycol (E.GL) and Engine oil (E.Oil) with Nanoparticles at 333K (continued)

Nano particle %

E.Gl + Al

E.Oil+Cu

E.Oil

+Au

E.Oil

+Ag

E.Oil +Al

CFX

Experimental

CFX

Experimental

CFX

Experimental

1

3919.66

4022.3

2063.1

2098.13

2611.27

2063.21

2062.78

2125.35

3

4212.63

4275.7

2203.46

2258.93

2685.83

2203.89

2202.32

2428.8

5

4523.97

2351.2

2763.99

2352.03

2349.1

7

4851.74

2505.11

2843.93

2506.48

2493.56

9

5195.2

2664.68

2924.94

2666.71

2659.89

11

5555.59

2830.4

3007.39

2833.25

2823.93

13

5934.99

3003.09

3092.09

3006.93

2994.63

15

6335.11

3183.36

3179.35

3188.41

3172.65

17

6757.88

3372.03

3269.79

3378.49

3358.75

19

7205.07

3569.77

3363.77

3577.91

3553.57

21

7678.88

3777.6

3461.99

3787.74

3758.06

23

8182.34

3996.7

3565.12

4009.16

3973.32

25

8717.26

4229.73

3673.56

4243.13

4200.22

Figure 5. Heat transfer co-efficient of water at 333K

Figure 6. Heat transfer co-efficient of Water with Nano particles at 333K

Figure 7. Heat transfer co-efficient of ethyleneglycolat333K

Figure 8. Heat transfer co-efficient of Ethylene glycol with Nano particles at 333K

Figure 9. Heat transfer co-efficient of engineoil at 333K

Figure 10. Heat transfer co-efficient of Engineoil with Nanoparticles at 333K

The analytical work is carried out with a CFX11.0 module inside the tubular structure, as shown in Figure 4. The modeling is done in Ansys Workbench 11.0 and imported into CFX11.0 software to analyse the flow and finding the heat transfer co-efficient of water.

From the analysis, it is found that the heat transfer coefficient (Figure 5) for water is 13048.1 W/ m2K at 333K. From Table 7 or Figure 6, it is seen that the Nano fluids other than copper, gold, silver and aluminum Nanoparticles mixture with water proves a higher heat transfer rate than water in both experimental and simulation method. Likewise, it is found that the heat transfer coefficient (Figure 7) for ethylene glycol is 3781.16 W/ m2K at 333K.

From Table 8 or Figure 8, it is seen that the Nano fluids other than copper, gold, silver and aluminum Nanoparticles mixture with ethylene glycol proves a higher heat transfer rate than ethylene glycol in both experimental and simulation method. Also, it is found that the heat transfer coefficient (Figure 9) for engine oil is 1996.36 W/ m2K at 333K. From Table 7 or Figure 10, it is seen that the Nano fluids other than copper, gold, silver and aluminum Nanoparticles mixture with ethylene glycol proves a higher heat transfer rate than engine oil in both experimental and simulation method.

5. Conclusions

This paper solves the convective heat transfer problem using a heated tube at 333K over base and Nano fluids and that includes: water, ethylene glycol and engine oilas base fluids and Water/ Nano particles of Copper, Gold, Silver and Aluminum, Ethyleneglycol/ Nanoparticles of Copper, Gold, Silver and Aluminum, Engineoil/ Nanoparticles of Copper, Gold, Silver and Aluminum as Nano fluid combination. The performance results prove that the Nano fluids possess higher heat transfer coefficient than the base fluid under constant Reynolds number. The Nanoparticles suspended in the base fluid increases constantly the performance of convective heat transfer rate and it could further be concluded that with constant Reynolds number, the heat transfer coefficient has increased with its associated particle volume fraction.

Nomenclatures

vi      [ms-1]        velocity in ith position

tmax   [min]        maximal time limit

T0     [K]              initial temperature

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