Energy analysis of three ventilation systems for a large machining plant

Manufacturing industries play an important role in economic development, but a large amount of energy is consumed in the removal of pollutants and heat generated on the manufacturing floor. An efficient ventilation system is needed for improving indoor air quality and thermal comfort at reduced energy cost. This study studied a displacement ventilation system with diffusers around columns for a machining plant, and compared its energy consumption with that of a perfect mixing ventilation system and the existing ventilation system in the plant. This investigation used computational fluid dynamics (CFD) to determine the vertical air temperature gradient in the plant, and the impact of temperature gradient on energy was estimated by means of building energy simulations (BES). The annual energy cost for the improved displacement ventilation system was 17.5% lower than that for mixing ventilation and 20.3% lower than for the existing ventilation system. However, because a large amount of outdoor air was used in winter, the heating energy consumption with the displacement ventilation was slightly higher than with the other two ventilation systems.