Interaction effects of radiation and convection measured by a thermal manikin wearing protective clothing with different radiant properties

As part of the EU funded research project THERMPROTECT (“Thermal properties of protective clothing and their use”) this paper deals with manikin experiments on the effects of heat radiation at different wind speeds, considering aspects related to the reflectivity of the clothing. A heated thermal manikin “Newton” was operated with a constant surface temperature of 34 °C standing in a climatic chamber. The manikin was placed in a wind tunnel, with fans sucking the air through the tunnel and the manikin facing the wind and the radiation. To ensure proper operation of the manikin’s heating mechanism the experiments were carried out at a low air temperature (Ta) of 6 °C with 50% relative humidity. Four wind speeds (0.5m/s, 1.0m/s, 2.0m/s and 5.0m/s) were used. The manikin wore four different outer wears (Black Laminated Nomex, Black Nomex, Orange Nomex and Reflective Nomex). All clothing had equal design. Identical underwear was worn in all trials (Helly Hansen super bodywear). Two THORN compact high intensity floodlight for PAR64 sealed beam CSI lamps were used in the tests as the radiant source. Lamps were set at a distance of 1.5metres away from the manikin for high radiation level (±450 W/m2) and 2.0 meters for medium level (±325 W/m2). The results showed a decrease in whole body heat loss, i.e. heat gain for the conditions with radiant heat stress compared to the reference without radiation. With wind, the heat gain decreased. Except for the reflective suit, the influence of the material and colour of the outer garment on radiant heat gains was negligible. The reflective suit showed the lowest heat gain. Increased heat loss by wind compensated for the radiant heat gains, with an effect size similar for all suits up to 2 m/s wind. Above this speed the wind effect on the reflective suit was smaller than for the others. The data obtained can be used to predict heat gain of humans by radiation in the presence of air movement.