Lee's Disc Apparatus

Model: HO-ED-M-03

Holmarc's Lee's Disc Apparatus (Model : HO-ED-M-03) is designed for the measurement of thermal conductivity in bad conductors. Thermal conductivity is the property of a material that indicates its ability to conduct heat. Conduction takes place if there exists a temperature gradient in a solid (or stationary fluid) medium.

Energy is transferred from more energetic to less energetic molecules when neighboring molecules collide. Conductive heat flow occurs in the direction of the decreasing temperature because higher temperature is associated with higher molecular energy.

Lee's Disc Apparatus comprises of a brass disc resting on another slab of the same dimension with special heating coil. Both metallic discs have radial holes for the sensitive thermistors. Material under test is placed in between two discs. The heater is turned on and the apparatus is left idle until the temperature gets stabilized. At this point the heat energy passing through the heat sample will be exactly equal to the heat flowing out of the lower block.

Maximum temperature the disc can achieve during the experiment is around 50 degree Celsius to make it safe for handling with even bare hands. Similarly, operating voltage for heating coil sandwiched between the discs is fixed as 50 V for safety. The temperature sensors used are highly sensitive and accurate with least count as low as 0.2 degree Celsius. Front panel is equipped with digital display and keyboard for user friendly operation.

This Apparatus provides the facility for performing experiments using different kinds of sample materials. The front panel includes LCD display and keyboard for readouts and settings.

Experiment Examples

To determine thermal conductivity of bad conductors (Glass, Nylon, Plywood, etc.) in the form of a disc using Lee's method.

Thermal conductivity,

k  =  (Mc dT / dt )  /  (πr2 (T2 - T3) )  ×  (r + 2h) d / 2( r + h) W  /  mK-1

Where,

M = Mass of the metallic disc

c = Specific heat capacity of the metallic disc

h = Height of the metallic disc

r = Radius of the metallic disc

dT / dt = Rate of cooling of the metallic disc at T2

d = Thickness of the cardboard disc,

T2 - T3 = Steady temperatures recorded at T2 and T3 respectively

Features

New and integrated design

Different samples can be tested

LCD display is provided for accurate measurement

Manual mode, auto mode and PC mode are possible

User friendly equipment
Related Topics

Thermal conductivity

Heat transfer

Specific heat capacity
Scope of Supply

Lees Disc Control Unit

Model No: ED-M-03-LDCU
Input
:
230V 5Amp AC
Quantity
:
1 no.

Heating Unit with Disc

Model No: ED-M-03-HUD
Operating Voltage
Manual Model
:
50 V
Quantity
:
1 no.

Brass Disc

Model No: ED-M-03-BD
Material
:
Cartridge Brass
Diameter
:
76.2 mm
Height
:
23.1 mm
Quantity
:
2 no.

AC Power Code

Model No: ED-M-03-APC
Type
:
3 core 3 Pin
Quantity
:
1 no.

RS 232 PC Cable

Model No: ED-M-03-RSC
Length
:
5 meters
Quantity
:
1 no.

Test Samples

Model No: ED-M-03-TS
Material
:
Borofloat glass, Teflon, Plywood
Quantity
:
1no. each

Accessories

Software CD
Heat Sink Compound
User Manual
Net Book PC (Optional)