Air distribution in convex wall jets for ventilation with a constant air flow

Abstract

The scheme of air exchange organization using air supply above a working zone by convex wall jets that interact with each other has been substantiated. This scheme is advisable in cases where it is impossible to supply air directly to the working zone. It provides optimal microclimate parameters with minimal recirculation of polluted air from the upper zone. Simulation of the air exchange organization in an exhibition hall in International Exhibition Centre in Kyiv with ventilation at a constant air volume (CAV) has been performed. The floor area is 5258 m2, the height is 19 m, the minimum outdoor air flow is 21.667 m3/s (78000 m3/h). The current design scheme of air exchange organization is zonal. General air exchange is 43.3333 m3/s (156000 m3/h). Recirculation is accepted 50 %. The air flow supplied in the upper and middle zones is, respectively, 22.5 m3/s (81000 m3/h) and 20.833 m3/s (75000 m3/h). Inlet air has temperature 291.65 K (18.5 °C). It is supplied downward by twisted jets. There are 65 Trox VDL-AHLD-E3/800/0/0/0/RAL 9010 air diffusers with a diameter of 800 mm. The proposed scheme is single-zonal using 24 diffusers PES-D-8-10/15-0,9 4 m above the floor and air removal from the upper zone. This scheme allows halving the air exchange to the minimum outdoor air without recirculation. The air temperature should be decreased by 3.3 K to 288.35 K (15.2 °С). The number of air-conditioners is decreased twice. The calculated consumption of cold decreased by 65.58 W/m2 or 29 %, the calculated consumption of heat for the second heating – by 7.17 W/m2 or 18 %. Saving of capital investments in prices of February 2020 is 792.16 UAH/m2 or 55 %, and decrease of operating costs for the cooling period is 6.61 UAH/m2 or 15 %. Thus, the system is economically beneficial from the beginning of its installation. In the future, its operation will be simulated in a mode with a variable flow rate.