Armfield Engineering Education
HEAT TRANSFER AND THERMODYNAMICS
HT11 Linear Heat Conductor - Issue 6
The Armfield Linear Heat Conduction accessory has been designed
to demonstrate the application of the Fourier Rate equation to simple steady-state
conduction in one dimension.
The unit can be configured as a simple plane wall of uniform material and
constant cross sectional area or composite plane walls with different materials
or changes in cross sectional area to allow the principles of heat flow
by linear conduction to be investigated. Measurement of the heat flow and
temperature gradient allows the thermal conductivity of the material to
be calculated.
The design allows the conductivity of thin samples of insulating material
to be determined.
Ordering Specification
• A small scale accessory designed to introduce students to the principles
of linear heat conduction, and to allow the thermal conductivity of various
solid conductors and insulators to be measured.
• Comprises a heating section, cooling section plus four intermediate
section conductor samples and two insulator samples.
• The heating section, cooling section and one of the intermediate
sections are fitted with thermocouples (8 in total) evenly spread along
the length of the assembled conduction path. • All sections are insulated
to minimise eroors due to heat loss.
• Heater power variable up to 60 Watts.
• Heating and cooling sections, 25mm diameter.
• The accessory is mounted on a PVC baseplate which is designed to
stand on the bench top and connect to the Heat Transfer Service Unit without
the need for tools.
• A comprehensive instruction manual is supplied.
Technical Details
The accessory comprises a heating section and cooling section which can be simply clamped together or clamped with interchangeable intermediate sections between them, as required. The temperature difference created by the application of heat to one end of the resulting wall and cooling at the other end results in the flow of heat linearly through the wall by conduction.
The heating section is manufactured from 25mm diameter cylindrical brass bar with a cartridge type electric heating element installed at one end. The heating element is operated at low voltage for increased operator safety and is protected by a thermostat to prevent damage by overheating. The heating element is rated to produce 60 Watts nominally at 24V DC. The power supplied to the heating element can be varied and measured using the HT10X. Three thermocouples are positioned along the heated section at uniform intervals of 15mm to measure the temperature gradient along the section. The cooling section is manufactured from 25mm cylindrical brass bar to match the heating section and cooled at one end by water passing through galleries in the section. Three thermocouples are positioned along the cooling section at uniform intervals of 15mm to measure the temperature gradient along the section.
Quick-release connections allow rapid connection to a cold water supply. A pressure regulator is incorporated to minimise the effect of fluctuations in the supply pressure. A manual control valve allows the flow of cooling water to be varied, if required, over the operating range of 0-1.5 litres/min. Measurement of the cooling water flowrate is not essential to the teaching exercises but an optional turbine type flow sensor can be fitted if required using the quick-release fittings. The optional flow sensor (Order code SFT2) connects directly to the HT10X to provide readings of cooling water flowrate directly in litres/min.
Four intermediate sections are supplied as follows:
• 30mm long brass section of the same diameter as the heating and
cooling sections and fitted with two thermocouples at the same intervals.
When this section is clamped between the heating and cooling sections a
long plane wall of uniform material and cross section is created with temperatures
measured at eight positions.
• Stainless steel section of the same dimensions as the brass section
to demonstrate the effect of a change in thermal conductivity.
• Aluminium section of the same dimensions as the brass section to
demonstrate the effect of a change in thermal conductivity.
• 30mm long brass section reduced in diameter to 13mm to demonstrate
the effect of a change in cross sectional area.
The heat conducting properties of insulators may be found by simply inserting the paper or cork specimens supplied between the heating and cooling sections.
A tube of thermal paste is provided to demonstrate the difference between good and poor thermal contact between the sections.
The heating section, cooling section and all intermediate sections are
located co-axially inside plastic housings which provide an air gap and
insulate the section to minimise heat loss to the surroundings and prevent
burns to the operator. All temperatures are measured using K-type thermocouples,
each fitted with a miniature plug for direct connection to the service unit
HT10X. Eight thermocouples in total are installed along the heated, intermediate
and cooling sections. The linear heat conduction accessory is mounted on
a PVC baseplate which stands on the bench top alongside the HT10X. The intermediate
sections and samples of insulators are stored on the baseplate when not
in use.
Experimental Capabilities
• Understanding the use of the Fourier Rate Equation in determining
rate of heat flow through solid materials
• Measuring the temperature distribution for steady-state conduction
of energy through a uniform plane wall and a composite plane wall
• Determining the constant of proportionality (thermal conductivity
k) of different materials (conductors and insulators)
• Measuring the temperature drop at the contact face between adjacent
layers in a composite plane wall (contact resistance)
• Measuring the temperature distribution for steady-state conduction
of energy through a plane wall of reduced cross-sectional area
• Understanding the application of poor conductors (insulators)
• Observing unsteady-state conduction (qualitative only)
Essential Armfield equipment
HT10X Heat Transfer Service Unit
Optional Armfield Accessories
HT10X-304 Educational Software with USB interface
Requirements
Cold water supply:
1.5 litres/min @ 1 Barg
Shipping Specification
Volume: 0.04m³
Gross weight: 5kg
Overall dimensions
Height: 0.29m
Width: 0.43m
Depth: 0.21m
|
 |
|---|
