Effects of non-isothermal and intermittent air movement on human thermal responses.

Twenty-four college students are asked about their subjective responses to a dynamic thermal environment with non-isothermal and intermittent air movement. The subjects wear an uniform of 0.6 clo and are sedentary. A rotative air jet can cyclically sweep over the subjects with adjustable air velocity. Each experiment lasts 150 minutes and is performed with three stages. Changing pattern of TSV and TCV over time, the effects of the frequency of the rotative jet on human's thermal sensation and thermal comfort, and the relation between the rotative frequency of the air jet and the velocity sensed by the subjects are studied. Non-isothermal and intermittent cool jet improves the subjects' thermal conditions significantly and increased their acceptance of the thermal environment. The subjects respond immediately to the temperature step-change, and as time passes by, the sensitivity to the cool air is diminishing. The sensed velocities are variable at different rotative speeds of the outlet. Under different air temperature conditions, the preferred speed of rotation is varied.