Implementation of a code to obtain globe and wet-bulb temperatures for application of the WBGT index in the evaluation of the thermal performance of industrial sheds via computational simulations

Resumo

For the analysis of the occurrence of overload or thermal discomfort in an industrial environment subject
to extreme temperatures, it is necessary to know the environmental conditions of the site. Extreme temperatures
are understood as those that cause serious health risks to workers. In this paper, an algorithm is implemented for
obtaining the hourly globe and internal wet bulb temperatures necessary to determine the WBGT index. The
WBGT index consists of a thermal overload index, defined by a mathematical equation that correlates the globe

temperature and wet-bulb temperature measured in the workplace. An industrial building equipped with a high-
intensity internal heat source and with longitudinal and/or transversal ridge vents is used as the object of study.

The internal environmental conditions of the shed are obtained through computer simulation using the EnergyPlus®
software (version 8.7.0), in three configurations of the devices that provide natural ventilation. The globe
temperature and wet-bulb temperature are not possible outputs to be obtained directly from the EnergyPlus
software and, for this reason, they are found through the algorithms formulated from iterative techniques.
Basically, three variables related to the environment are of interest: temperature, air speed, and relative humidity.
The proposed algorithms converge properly and, when comparing the final annual results of the WBGT index with
the limits provided for in the Brazilian regulatory standard NR-15, it is observed that the shed equipped with
longitudinal and transversal ridge vents has better thermal performance, thus providing less time of discomfort due
to the heat.