MEASURING AIR TEMPERATURE IN PROXIMITY TO THE HUMAN BODY

Françoise Thellier (1) , Françoise Monchoux (1) , Sabine Piniec (2)

1 PHASE - Laboratoire Physique de l'Homme Appliquée à Son Environnement
2 LESETH - Laboratoire Energétique des Systèmes Et Thermique de l'Homme

To analyse and improve a human being's local thermal comfort through simulation and/or experiments, a good description of the thermal environment is needed. Many local physical data are indispensable to calculate body heat exchanged during transient conditions in a non-homogeneous environment. Special problems appeared for air temperature near the body, it has to be measured very close to the surface, but the person needs to move, so the probes have to be fixed on him. The ISO recommends protecting the probe against radiation by a low-emissivity protective screen and increasing air velocity so the probe's temperature is close to that of the air. In our case, air velocity cannot be increased because it will then changed convective and evaporative exchanges on the skin surface itself. These problems appear when extremely non-homogeneous thermal conditions, e.g. in cars, are studied. The purpose of this paper is to show that when the air is cold and surfaces are hot, the air temperature measured close to the body is overestimated. Experiments were performed to understand the influence of the protective screen. A regulated plate was used to represent the skin. It was equipped with different types of probes and a variety of thermal conditions were created. The temperature of the probe was strongly influenced by the screen, which was warmed up partly by radiation coming from the environmental surfaces and partly by conduction. There were also problems with the aerodynamic flow in and around the screen. In this communication we try to quantify the phenomenon of heat transfer and separate the different modes. The discussion may lead to other recommendations about how to measure air temperature close to surfaces that have temperatures different from that of the air.

Domaines: Thermique [physics.class-ph]

Françoise Thellier, Françoise Monchoux, Sabine Piniec. MEASURING AIR TEMPERATURE IN PROXIMITY TO THE HUMAN BODY. Moving Thermal Comfort Standards into the 21st Century, Apr 2001, Cumberland Lodge, Windsor ,, United Kingdom. ⟨hal-02175347⟩