Armfield Engineering Education
HEAT TRANSFER AND THERMODYNAMICS
HT15 Extended Surface Heat Exchanger - Issue 6
A long horizontal rod, which is heated at one end, provides
an extended surface (pin) for heat transfer measurements. Thermocouples
at regular intervals along the rod allow the surface temperature profile
to be measured. By making the diameter of the rod small in relation to its
length, thermal conduction along the rod can be assumed to be one-dimensional
and heat loss from the tip can be ignored. The measurements obtained can
be compared with a theoretical analysis of thermal conduction along the
bar combined with heat loss (heat transferred) to the surroundings by the
modes of free convection and radiation simultaneously.
Ordering Specification
• A small scale accessory designed to demonstrate the temperature
profile and heat transfer characteristics for an extended surface when heat
flows along the rod by conduction and heat is lost along the rod by combined
convection and radiation
• The extended surface comprises a 10mm diameter, long brass rod mounted
horizontally and heated at one end with a 20 Watt, 24V DC heater.
• Eight thermocouples mounted at 50mm intervals along the rod provide
the temperature distribution.
• Temperature of the ambient air is measured by an independent thermocouple.
• 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 rod is manufactured from a solid cylindrical brass bar with a constant diameter of 10mm. The rod is mounted horizontally with support at both ends and positioned to avoid the influence of adjacent surfaces. The rod is heated by a cartridge type electric heating element which operates at low voltage for increased operator safety and is protected by a thermostat to prevent damage from overheating. The heating element is inserted co-axially into the end of the rod and is rated to produce 20 Watts nominally at 24V DC into the rod. The power supplied to the heated rod can be varied and measured on the HT10X. Eight thermocouples are attached to the surface of rod at equal intervals of 50mm giving an overall instrumented length of 350mm. Each thermocouple is wrapped around the rod to minimise errors by conduction. One thermocouple is mounted adjacent to the heated rod to measure the ambient air temperature. All temperatures are measured using K-type thermocouples, each fitted with a miniature plug for direct connection to the service unit HT10X. The rod is coated with a heat resistant matt black paint which provides a consistent emissivity close to unity The heated end of the rod is mounted co-axially inside a plastic housing which provides an air gap and insulates the area occupied by the heater to minimise heat loss and prevent burns to the operator.
The accessory is designed to be used in conjunction with the HT10X Heat Transfer Service Unit and is assembled on a mounting plate to stand on the bench alongside the HT10X.
Experimental Capabilities
• Measuring the temperature distribution along an extended surface
(pin) and comparing the result with a theoretical analysis
• Calculating the heat transfer from an extended surface resulting
from the combined modes of free convection and radiation heat transfer and
comparing the result with a theoretical analysis.
Essential Armfield Equipment
HT10X Heat Transfer Service Unit
Optional Armfield Accessories
HT10X-304 Educational Software with USB interface
Shipping Specification
Volume: 0.01m3
Gross Weight: 5kg
Overall dimensions
Height: 0.15m
Width: 0.50m
Depth: 0.15m
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