Thermal scheme

C

N

K

Mode of thermal flow

Horizontally located cylinder

0,54

0,25

1

Laminar flow

0,1

0,33

1

Turbulent flow

Vertical surface and vertically located cylinder with a big diameter D in relation to the length L

0,8

0,25

Laminar flow

For obtaining of Nu is used :

C=0,6; X=x;

0,0246

0,4

Turbulent flow

For obtaining of Nu is used :

C=0.0296; X=x;

Vertically located cylinder with not big diameter D in relation to the length L

0,686

0,25

Laminar flow

Horizontal surface. Thermal flow is directed upward

0.54

0,25

1

Laminar flow

0.14

0.33

1

Turbulent flow

Horizontal surface. Thermal flow is directed downward

0.27

0.25

1

Only for laminar flow

Sloped surface

0,8

0,25

Laminar flow (Gr is multiplied by cos Φ in the formula of the vertical lamina)

Sphere

0,49

0,25

1

Laminar flow (air)

Two vertical laminae with different temperatures

0.04

1

Air layer

Vertically located thick cylinder

0,01

1

Air column

Two vertically located surfaces. (the upper is hotter)

-

-

-

 

Ideal conditions:

0.27

0.25

1

Laminar flow (air)

3.105< Gr.Pr<3.1010

Two vertically located surfaces. (the lower is hotter)

0,195

0.25

Pr-0,25

Laminar flow (air)

104< Gr <4.105

0.068

0.33

Pr-0,25

Turbulent flow (air)

Gr>4.105

Two parallel vertical surfaces with different temperatures (equal a)

0,18

0.25

Laminar flow (air)

2.104< Gr<4.105

0.065

0.33

Turbulent flow (air)

2.105<Gr<107

Two parallel sloped surfaces

 

 

Nuv vertical direction

Nuv horizontal direction

Two co-axis cylinders

0,317

0,25

Laminar flow

Two concentric spheres

0,61

0.25

Laminar flow

 

 

 

 

T,[K]

r, [kg/m3]

Cp, J/kg.K

m, [kg/(m.s)]

l, [W/m.K]

Pr

b,[K-1]

100

150

200

250

300

350

400

450

500

550

600

650

700

750

800

850

900

950

1000

1100

1200

1300

1400

1500

1600

1700

1800

1900

2000

2100

2200

2300

2400

2500

3.601

2.3675

1.7684

1.4128

1.1774

0.998

0.8826

0.7833

0.7048

0.6423

0.5879

0.543

0.503

0.4709

0.4405

0.4149

0.3925

0.3716

0.3524

0.3204

0.2947

0.2707

0.2515

0.2355

0.2211

0.2082

0.197

0.1858

0.1762

0.1682

0.1602

0.1538

0.1458

0.1394

1027

1010

1006

1005

1006

1009

1014

1021

1030

1039

1055

1064

1075

1086

1098

1110

1121

1132

1142

1160

1179

1197

1214

1230

1248

1267

1287

1309

1338

1372

1419

1482

1574

1688

0.000006924

0.000010283

0.000013289

0.00001488

0.00001983

0.00002075

0.00002286

0.00002484

0.00002671

0.00002848

0.00003018

0.00003177

0.00003332

0.00003481

0.00003625

0.00003765

0.00003899

0.00004023

0.00004152

0.0000444

0.0000469

0.0000493

0.0000517

0.000054

0.0000563

0.0000585

0.0000607

0.0000629

0.000065

0.0000672

0.0000693

0.0000714

0.0000735

0.0000757

0.00925

0.01374

0.01809

0.02227

0.02624

0.03003

0.03365

0.03707

0.04038

0.04360

0.04659

0.04953

0.0523

0.05509

0.05779

0.06028

0.06279

0.06525

0.06752

0.0732

0.0782

0.0837

0.0891

0.0946

0.1

0.105

0.111

0.177

0.124

0.131

0.139

0.149

0.161

0.175

0.77

0.753

0.739

0.722

0.708

0.697

0.689

0.683

0.680

0.680

0.680

0.682

0.684

0.686

0.689

0.692

0.696

0.699

0.702

0.704

0.707

0.705

0.705

0.705

0.705

0.705

0.704

0.704

0.702

0.7

0.707

0.71

0.718

0.73

0.01

0.00667

0.005

0.004

0.00333

0.00286

0.0025

0.00222

0.002

0.00182

0.00167

0.00154

0.00143

0.00133

0.00125

0.00118

0.00111

0.00105

0.001

0.000909

0.000833

0.000769

0.000714

0.000667

0.000625

0.000588

0.000556

0.000526

0.0005

0.000476

0.000454

0.000435

0.000417

0.0004