HEAT TRANSFER AND THERMODYNAMICS
HT13 - Laws of Radiant Heat Transfer and Radiant Heat Exchange - Issue 6
This Armfield accessory has been designed to demonstrate the
laws of radiant heat transfer and radiant heat exchange using light radiation
to complement the heat demonstrations where the use of thermal radiation
would be impractical. The equipment supplied comprises an arrangement of
energy sources, measuring instruments, aperture plates, filter plates and
target plates which are mounted on a linear track, in different combinations,
to suit the particular laboratory teaching exercise chosen.
Ordering Specification
• A small scale accessory designed to introduce students to the basic
laws of radiant heat transfer and radiant heat exchange.
• A heat source with radiometer and a light source with light meter
are used where appropriate to demonstrate the principles.
• The heat source consists of a flat circular plate 100mm in diameter
which incorporates a 216 Watt electric heating element (operating at at
24V DC maximum).
• The light source consists of a 40 Watt light bulb (operating at
24V DC maximum) mounted inside a housing with a glass diffuser.
• The heat and light sources, instruments, filters and plates are
mounted on an aluminium track with graduated scale 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 track consists of a rigid aluminium frame with twin horizontal rails which incorporates sliding carriages to allow the positions of the instrumentation, filters and plates to be varied. The position of the carriages relative to the energy source can be measured using a graduated scale attached to the side of the track. The track is designed to stand on the bench top alongside the HT10X Heat Transfer Service Unit. The heat source consists of a flat copper plate which is heated from the rear by an insulated electric heating element which operates at low voltage for increased operator safety. The front of the plate is coated with a heat resistant matt black paint which provides a consistent emissivity close to unity. The surface temperature of the plate is measured by a thermocouple which is attached to the front of the plate.
The heating element is rated to produce 216 Watts nominally at 24V DC into
the plate which is 100mm in diameter. The power supplied to the heated plate
can be varied and measured using the HT10X. The heated plate is mounted
at one end of the calibrated track inside a protective cage which prevents
inadvertent contact with the hot surface. Radiation from the heated plate
is measured using a heat radiation detector (radiometer) which can be positioned
along the graduated track on a carriage. The radiometer is connected to
the HT10X to provide readings calibrated directly in units of W/m2. Metal
plates with different surface finishes are supplied to demonstrate the effect
of emissivity on radiation emitted and received. Two black plates, one grey
plate and one polished plate are supplied together with a track mounted
carrier which positions the plates in front of the heat source. Each plate
incorporates a thermocouple to indicate the surface temperature of the plate.
Surface temperatures of the heat source and metal plates are all measured
using K-type thermocouples, each fitted with a plug for direct connection
to the service unit HT10X. Two cork-coated metal plates are supplied that
allow a vertical slot aperture of adjustable width to be created between
the source and detector to demonstrate area factors. The light source consists
of a lamp in a housing with a glass diffuser and operates at low voltage
for increased operator safety. The source may be rotated through 1800 and
the angle measured using an integral scale. The lamp is rated to produce
40 Watts nominally at 24V DC. The power supplied to the lamp can be varied
and measured on the HT10X. The light source is mounted at one end of the
calibrated track. Radiation from the light source is measured using a light
meter which can be positioned along the graduated track on a carriage. The
light meter is connected to the HT10X to provide readings of illumination
calibrated directly in units of Lux. Filter plates of varying opacity and
thickness are supplied to demonstrate the laws of absorption.
Experimental Capabilities
• Inverse Square Law using the heat source and radiometer or light
source and lightmeter
• Stefan Boltzmann Law using the heat source and radiometer
• Emissivity using the heat source, metal plates and radiometer
• Kirchoff Law using the heat source, metal plates and radiometer
• Area factors using the heat source, aperture and radiometer
• Lamberts Cosine Law using the light source (rotated) and lightmeter
• Lamberts Law of Absorption using the light source, filter plates
and lightmeter
Essential Armfield Equipment
HT13 requires the HT10XC Computer Controlled Heat Transfer Service Unit.
(HT13 to be used under manual control only)
Optional Armfield Accessories
HT10X-304 Educational Software with USB interface
Shipping Specification
Volume: 0.3m³
Gross Weight: 12kg
Overall dimensions
Height: 0.44m
Width: 1.23m
Depth: 0.30m
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