Abstract
Convective and radiation heat transfer take place between various objects
placed in open air space and their surroundings. These phenomena bring
about heat losses from pipelines, building walls, roofs and other objects.
One of the main tasks in energy auditing is the reduction of excessive
heat losses. In the case of a low sky temperature, the radiation heat
exchange is very intensive and the temperature of the top part of the
horizontal pipelines or walls is lower than the temperature of their
bottom parts. Quite often this temperature is also lower than the
temperature of the surrounding atmospheric air. In the case of overhead
heat pipelines placed in open air space, it is the ground and sky that
constitute the surroundings. The aforementioned elements of surroundings
usually have different values of temperature. Thus, these circumstances
bring about difficulties during infrared inspections because only one
ambient temperature which represents radiation of all surrounding elements
must be known during the thermovision measurements. This work is aimed at
the development of a method for determination of an equivalent ambient
temperature representing the thermal radiation of the surrounding elements
of the object under consideration placed in open air space, which could be
applied at a fairly uniform temperature of the sky during the thermovision
measurements as well as for the calculation of radiative heat losses.
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