The effect of front pattern perforation shape on thermal sensations of occupants in personalized ventilation systems.

Abstract The aim of this study was to find the most favourable shape of the front panel perforation shape, which would allow us to obtain the greatest cooling effect and – at the same time – be positively perceived by the people. The capacity of the personalized ventilation (PV) system to affect human thermal sensation, with different shapes of front panel perforation used, was analyzed. Once the pilot study was conducted, it used a rectangular nozzle of front pattern size 320 mm × 125 mm and six different front patterns perforation shapes with round holes were tested. Operational parameters such as: airflow 20 l/s, supply air temperature at 24 °C or ambient temperature at 28 °C were invariable. The experiment consisted of a two-stage analysis of air jets characteristics and of tests in which people participated. Twenty-five male volunteers, at the age of 22–23 were engaged. They their assessed thermal sensation and completed relevant questionnaires. On the basis of the results of the above study, differences in jet characteristics depending on the pattern shapes and their different impact on thermal sensation of the volunteers were demonstrated. The biggest cooling effect was obtained using front panels with small hole size (d = 5 mm). These perforations allowed us to obtain a more even air outflow from the entire panel. This ensured a broader airflow of lower velocity, reaching and affecting a larger area. With holes of larger size (d = 15 mm), air outflow occurred mainly through the central part, which produced narrow jets of higher velocity. Highlights • Determining velocity profiles for personalized jets with different front pattern shapes. • Questionnaire based assessment of the impact of different front patterns on thermal sensation of the occupants in PV. • Demonstrating statistically significant differences between the front patterns used and thermal sensation of the volunteers. [ABSTRACT FROM AUTHOR]