Influence and Optimal Operating Parameters of Slit Make-Up Air System on Low-Energy Kitchen Environment

Low-energy buildings make it difficult for the waste heat and pollutants in the kitchen to escape from indoors to outdoors due to their high air tightness and low air permeability. Therefore, a local make-up air system is needed to enhance the air change rate in the kitchen area. This study presents a design for a three-side slit make-up air system and assesses its impacts on the thermal comfort and pollutant concentrations of low-energy kitchens in winter. Orthogonal experiments were conducted to quantitatively evaluate the exposure levels of PM2.5 and TVOC in the breathing area and to determine the optimal parameters for system design and operation. The results indicated that the maximum temperature difference between head and ankles with slit make-up air was 17.1 degrees C, which was 1.6 degrees C lower than that under the natural make-up air. The maximum vertical temperature increased by 5.8 degrees C as the make-up air temperature increased to -5 degrees C. Furthermore, the average concentrations of PM2.5 and TVOC in the breathing area decreased by 62.4 % and 40.5 %, respectively, compared with those without the slit make-up air system. The optimal parameters for pollutant control are make-up air velocity of 5 m/s, exhaust rate of 700 m3/h, and slit angle of 90 degrees. These experimental results indicated that the slit make-up air system could improve thermal comfort compared with natural make-up air systems and effectively reduce the concentration of kitchen pollutants in low-energy buildings in severely cold regions. This study provided fundamental information for further investigations on improving the kitchen environment of low-energy buildings.