Experimental Study on Ventilation Requirements of Exhaust Hoods for Multiple Cooking Appliances (ST-16-C003)

The purpose of this research was to investigate the ventilation requirements of an exhaust hood for multiple cooking appliances. There are two types of exhaust hoods in commercial kitchens: one is for a single cooking appliance, the other is for multiple cooking appliances. The face velocity of 60 fpm (0.3m/s) at the exhaust hoods opening is usually adopted as typical ventilation rate in Japanese commercial kitchen. Though the larger size of exhaust hoods opening increase the ventilation requirements, the amount of heat generation from cooking appliances under the exhaust hood is not reflected to the ventilation requirements. It seems to be necessary to know the ventilation requirements of exhaust hoods for multiple cooking appliances because the cooking appliances installed over multiple cooking appliances are various characteristics of heat generation. We investigated whether the sum of the ventilation requirements of exhaust hoods installed over each single cooking appliance is regarded as the ventilation requirements of exhaust hood for multiple cooking appliances. We measured capture efficiencies of exhaust hoods installed over single and multiple cooking appliances. Provided that the permissive level of capture efficiency is 90 percent, the ventilation rates of exhaust hoods for a fryer, noodle cooker, and IH table (single cooking appliance) were 253 cfm (430m³/h), 221 cfm (375m³/h), 194 cfm(330m³/h), respectively. The ventilation rates of exhaust hoods for a fryer with two IH tables and a noodle cooker with two IH tables (multiple cooking appliances) were 430 cfm (730m³/h) and 470 cfm (800m³/h), respectively. The sum of the ventilation rates of exhaust hoods for a fryer with IH tables and a noodle cooker with IH tables were 642 cfm (1090m³/h) and 610 cfm (1035m³/h), respectively. The sum of the ventilation rates for single cooking appliances is higher than that measured in the case of exhaust hoods for multiple cooking appliances. These results indicate that the capture and containment performance of exhaust hoods for multiple cooking appliances is higher than that of exhaust hoods for single cooking appliances. The size of exhaust hood’s opening for multiple cooking appliances is large compared with the exhaust hoods for single cooking appliances. Therefore it is easy for the exhaust hoods for multiple cooking appliances to capture thermal plumes even if thermal plumes are expanded by air disturbance. It suggests that the sum of the ventilation rates for single cooking appliances is the simplest way to estimate the ventilation rates for multiple cooking appliances.