Survey Study On Exhaust Fume Systems And Exhaust Air Rate Of Commercial Kitchen

Commercial kitchens（CK） produce a lot of heat,steam and fume pollutants in the cooking process.Cooking oil fume has complex components and contains a large number of fine particles and volatile organic gaseous pollutants（VOCs）.It not only pollutes indoor air,endangers human health,but also is an important precursor of air pollution.At present,the treatment of cooking oil fume pollution has been widely concerned.In this paper,the methods to determine the exhaust volume of CK fume exhaust system（FES） are summarized,and the status quo of Chinese restaurants fume exhaust system operation is investigated,so as to provide a basis for developing a FES design method suitable for Chinese CK.The main research contents of this paper are as follows:（1）There are three types of calculation methods for the exhaust air volume of commercial kitchens in various countries:thermal balance method,mass balance/control wind speed method and estimation method.When the cooker information is more comprehensive,for kitchens with less oil fume generation but large heat dissipation （such as Western restaurant）,the heat balance method can be preferentially used to calculate the exhaust air flow;for kitchens with large oil fume generation and heat dissipation（such as medium Restaurant）,is batter to use the mass balance method,and then use the heat balance method to check.When the parameters of above two methods are incomplete,the exhaust air volume calculation can be performed according to the estimation method.（2）Investigated the FES of 41 Chinese restaurants（CR）in Tianjin,including cooking equipment,fume hoods,purification equipment,exhaust fans,emission forms,air-makeup system,and grease accumulation at the discharge outlet.The results show:the main cooking equipment is cooking stove,when the kitchen area larger than 20m²,the number of cooking equipment is about 4;56.25% of the kitchen exhaust hoods are arranged by three sides against the wall;The sources of makeup air were adjacent room supplementary air （100%）,air penetration （68.3%）,mechanical supplementary fresh air （29.3%）,and air-conditioning supply air （17.1%）;According to the outdoor grease accumulation,when the number of cooking equipment exceeds 4,the cleaning cycle shall be controlled within 2 months.（3）The proportion of the annual thermal comfort and wet comfort of chefs in the kitchen with mechanical air supplement was 35.00% and 45.00%,respectively,which were better than those without mechanical air supplement（20.59% and 26.47%）.The kitchen with mechanical air supply has a high degree of satisfaction with the chef’s indoor environment.（4）Taking the cooking stove as an example,this paper simulates the exhaust system of commercial kitchen cooking stove based on CFD-Fluent technology,and analyzes the discharge of cooking pollutants and the working area environment under different exhaust air volume with CO₂ and C₆H₆ as representative factors.And concludes that the range of exhaust air volume corresponding to the model can guarantee the emission of pollutants is 1500 m³/h～1750 m³/h.