Characteristics Of Cooking Thermal Plume Diffusion In The Kitchen

Catering industry provides delicious food for the people,it also has brought the cooking fume pollution.because of complex cooking process,varieties of vegetable,cooking methods,hot jet change in commercial kitchen,it is difficult to control the smoke efficiently.Therefore,this dissertation studies oil fume diffusion rule of cooking process firstly,analysize its characteristics,and then study thermal jet Diffusion rules with mechanical exhaust,finally simulate exhaust effect of thermal hood duringcooking process.The main achievements are as follows:（1）Study onthefreediffusion rule of cookingplume without no interference,including characteristic parameters expression theory of theaxial velocity,sectional diameter,diffusion angle,thesectional flow,axial residual temperature.Select gasfurnace（3.6kW）,ashallowpot（diameter28cm,20cm deep）and a deep pot（diameter 28cm,depth 50cm）to make a case study.Test shows that theeffects ofthermal plume parameters areheat power,heat sourcesize,height.The diffusionangle remainedabout 24°when the cooking plumeis at 0.3m overthe furnace surface（equivalentto furnace diameter）.（2）Studyonairflowofcookingplumeunderthe mechanical exhaust.including theaxial velocity,section diameter velocity,diffusion angle,axialresidualtemperature,sectionalairflowrate.Select gasfurnace（3.6kW）,ashallowpot（diameter 28cm,depth20cm）to make a case study.Research shows thattheeffects ofthermal plume parameters areheat power,heat sourcesize,height,exhaustvolume.Diffusion angle is mostly affected by exhaustvolume.When it increases,diffusion angle varies from large to small tolarge.it remains a minimumvalue of 20°when air volumeis0.46m³/s.（3）Study on interaction relationship between thermal plume and exhaust flow field.When the exhaust air volume plays a dominant role,the linear relationship exist between the thermal plume diameter of any section and the diameter of the heat source,its shrink cross-section is not obvious,diameter of the heat source increases with the plume surface height;when the thermal plume leading a role,the thermal plume diameter is smallest,it shows a significant shrinkage,approximately linear relationship exists between the any section diameter of the thermal plume and the heat resource diameter.（4）Establish the model of cooking thermal plumes in the commercial kitchen,use experiment of a single factor and multi factors orthogonal,analyze its diffusion distribution of velocity,temperature,CO₂ concentration and air age,PMV,PPD at commercial kitchen work space through the 9 kinds of experiment schemes,the effect factors on the cooking plume is researched,optimization control scheme of oil plume is given.In the same case of source power,size and shape of hood,mechanical ventilation,air intlet position,hood installation height are the main factors.（5）Put forward a method of controlling the oil fume confined to one area.It can better guide the oil fume into exhaust hood through air-flow organization.It is conducive to protect the cook comfort from air supported by top blowing or air curtain.