Understanding Infrared Thermography Reading 3

■ Energy Conversion Differences
Energy conversion differences occur when energy is converted from one form
to another. Friction (mechanical energy converted to thermal energy) is a
commonly observed example of temperature changes because of energy
conversion. Another is electrical energy converted to thermal energy, as
illustrated in Figure 4.2, where the current carrying wire of a twisted pair
generates heat revealing insulation discontinuities. Exothermic or
endothermic reactions (chemical energy converted to thermal encrgy) are
further examples. typified by the heating that accompanies the curing of
polymers.
■ Direct Heat Transfer Differences
Direct heal transfer differences are also commonly observed in thermographic
survey programs. An example of this is shown in the direct transfer of thermal
energy through the wall of a catalytic cracker reformer vessel as illuslrated in
Figure 4.3. The differences in heat flow illustrate the differences in thermal
resistance between good refractory material and degraded material.
Charlie Chong/ Fion Zhang