An experimental investigation into the pull-down performances with different air distributions

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Original languageEnglish
Pages (from-to)151-162
Journal / PublicationApplied Thermal Engineering
Online published14 Aug 2015
Publication statusPublished - 5 Dec 2015


The purpose of this study is to investigate the loads and lengths of the pull-down periods (the time used to achieve a comfortable thermal environment before a room is ready for occupation) with mixing ventilation, displacement ventilation and stratum ventilation. In a typical classroom in Hong Kong, experiments begin with the same initial hot thermal environment. Based on ASHRAE 55-2010, ISO Standard 7730 and literature, existing indices PMV, PD and ADPI, calculated from measured data, are used as the thermal comfort criteria to determine the end of the pull-down period. The results indicate that stratum ventilation outperforms the other two air distributions during the pull-down period in terms of rapidity and energy consumption. For the rapidity of the pull-down process, mixing ventilation spends a shorter time than displacement ventilation, while stratum ventilation spends less than half of the time the other two spend. The average pull-down load of stratum ventilation is only around a quarter of that of mixing ventilation or displacement ventilation, The exergy consumption of the chilled water used for the pull-down of stratum ventilation is also lower than that of the other two distributions.

Research Area(s)

  • Energy consumption, Pull-down process, Rapidity, Stratum ventilation, Thermal comfort