HEAT TRANSFER AND THERMODYNAMICS
HT11 Linear Heat Conduction
HT11C Computer Controlled Linear Heat Conduction
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 units 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.
On the HT11C the heater power and the cooling water flow rate are controlled via the HT10XC, either from the front panel or from the computer software. On the HT11 these are controlled manually.
- A small-scale accessory to introduce students to the principles of linear heat conduction, and to enable the conductivity of various solid conductors and insulators to be measured
- Comprises a heating section, a 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 (eight in total) evenly spread along the length of the assembled conduction path
- All sections are thermally insulated to minimise errors due to heat loss
- Includes a water pressure regulator and a manual flow control valve
- Computer-controlled unit includes an electronic proportioning solenoid valve to control the cooling water flow rate and a water flow meter
- Heater power variable up to 60W
- Water flow rate variable up to 1.5 l/min
- Heating and cooling sections, 25mm diameter
- A comprehensive instruction manual is included
The accessory comprises a heating section and cooling section, which can be 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.
Thermocouples are positioned along both the heated section and cooled sections at uniform intervals of 15mm to measure the temperature gradient along the sections.
A pressure regulator is incorporated to minimise the effect of fluctuations in the supply pressure.
A control valve allows the flow of cooling water to be varied, if required, over the operating range of 0-1.5 l/min. The cooling water flow rate is measured by a turbine type flow sensor (HT11C only).
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 change in thermal conductivity
- Aluminium section of the same dimensions as the brass section to demonstrate the effect of change in thermal conductivity
- 30mm-long brass section reduced in diameter to 13mm to demonstrate the effect of 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.
- 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
HT11C and HT11 requires the HT10XC Computer Controlled Heat Transfer Service Unit.
(HT11 to be used under manual control only)
Cold Water Supply:
1.5 l/min @ 1 bar