Heat and hazardous contaminant transports in ventilated high-rise industrial halls

Abstract

Performances and efficiencies of displacement ventilation (DV) and partial ventilation (PV) for industrial halls of different configurations as well as the heat and mass transports within the industrial halls were numerically investigated. Three levels of Rayleigh number (5.8×10¹⁰, 1.0×10¹² and 2.1×10¹²) and two values of source contaminant flux (5 mg/s and 50 mg/s) were considered. The inlet Reynolds numbers were 2×10⁴, 5×10⁴, 1.5×10⁵ and 4.5×10⁵ for DV and 5×10⁵, 1×10⁶, 2×10⁶ and 4×10⁶ for PV, respectively. From the results, it is concluded that the above parameters have very complex impacts on the conjugated heat and mass transports. From points of view of acceptable indoor air quality and ventilation efficiency, PV at Re=1×10⁶ with side-located sources and 65% of the supply air extracted through floor level outlets is the best choice when Ra=5.8×10¹⁰. However, DVs at Re=5×10⁴ and Re=1.5×10⁵ with center-located sources and floor-mounted air suppliers are the best choices for Ra=1.0×10¹² and Ra=2.1×10¹², respectively. When source contaminant flux reaches 50 mg/s, local extraction as a supplement of general ventilation is recommended. The results can be a first approximation to 3D numerical investigation and preliminary ventilation system design guidelines for high-rise industrial halls.

Keywords

large space / general ventilation / highly turbulent flows / combined heat and mass transports

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