Experimental and Numerical Investigation of Air Distribution in a Large Space

A literature review has revealed that there is a very limited number of numerical or experimental studies of the air flow for mechanically ventilated large occupied rooms. Existing literature suggests that a room with more than 5 meters floor-to-ceiling height can be considered as a large space. The aim of this paper is to present a set of detailed air temperature and velocity measurements in a large open plan office located in south England. External weather conditions were monitored with a meteorological station located on the roof of the building to include air temperature, relative humidity, solar radiation and wind speed/direction. The monitored office has dimensions of 15.5m x 14m x 6m ceiling height with brick external walls and metal roof which includes two large skylights. The open plan office is used by 12 people with positioned desks and computers while lighting is provided by Theroux. The total internal gain heat load in the office is 27 W⁄m2. This large occupied open plan office is supplied by a mechanical cooling using overhead mixing ventilation system which operates during the summer months.
Measurements were carried out in the summer of 2016 which included some periods with external temperatures up to 28.9˚C and solar radiation up to 740 W⁄m2. The measurements were used to validate a Computational Fluid Dynamic (CFD) model of the office building executed using ANSYS Fluent. A comparison between numerical results and experimental results show good agreement. The validated CFD model was used to study in more detail the existing ventilation system and proposed improvements for its performance including further commissioning