Rev.

8/22/03

M E 431 SENIOR LAB

M E 431 SENIOR LAB

TRANSIENT COOLING IN THE PRESENCE

TRANSIENT COOLING IN THE PRESENCE

OF RADIATION AND CONVECTION

OF RADIATION AND CONVECTION

ADDITIONAL DATA FOR LAB ANALYSIS

Data For Biot Numbers

1

Thermal Conductivity (Al)

204

W/(m-C)

@120 C

2

Thermal Conductivity (Cu)

376

W/(m-C)

@120 C

Tolerances for Error Analysis

Property

Aluminum Values

Copper Values

Error in Measured Data:

1

Tolerance on Thermocouple Temp.

+/-1.45

C

measurement (Omega Data)

Density

2707

kg/m^3

8954

kg/m^3

2

Air Temperature

+/-0.2

F

(Mercury Thermometer)

(+/-0.11

C)

Specific Heat

0.896

kJ/kg-C

0.3831

kJ/kg-C

Tolerances in Properties:

Thermal Conductivity

228

W/m-C

376

W/m-C

3

Density

+/-60

kg/m^3

Sphere Diameter

4.928

cm

5.004

cm

4

Specific Heat

+/-0.001

kJ/(kg-C)

Thermal Coeff. of Expansion(Air)

0.00336

1/C @25C

0.00336

1/C @25C

(77 F)

(77 F)

5

Surface Temperature

+/- 1.45

C

Surface Temperature (ave)

120

C

120

C

6

Thermal Emissivity

+/- 0.043

Air Temperature

25

C

25

C

7

Thermal Conductivity (Air)

+/- 0.0002

(W/m-C)

(Avg Surf. temp + air Temp)/2

72.5

C

72.5

C

Thermal Conductivity (Air)

0.0291

W/m-C @72.5C

0.0291

W/m-C @72.5C

0.01735

(BTU/hr-ft-F)

0.01735

(BTU/hr-ft-F)

Prandlt Number

0.707

@ 72.5 C

0.707

@ 72.5 C

Kinematic Viscocity (@ 72.5 C)

1.97 X 10^-5

m^2/s

1.97 X 10^-5

m^2/s

0.98

ft^2/hr

0.98

ft^2/hr

Thermal Emissivity

0.242

0.352

Consider the following to be Exact:

g, the acceleration of gravity;

Stefen-Boltzmann Constant

D, Diameter of the Sphere

g, the acceleration of gravity

9.8

m/s^2

9.8

m/s^2

Air: Thermal Coeff. of Expansion , Prandlt No., and

417312000

(ft/hr^2)

4.17E+08

(ft/hr^2)

Kinematic Viscosity

Stefen-Boltzmann Constant

1.714 X10^-7

1.714 X10^-7