Design And Performance Evaluation Of Three-side Air Curtains Surrounding A Household Range Hood

Cooking activities generally produce a lot of cooking fumes,which contain a variety of toxic,harmful gases and particulates.Excessive inhalation by cooks will cause serious health risks.Therefore,in the daily cooking activities,range hoods are generally used to discharge cooking fume in time,while only part of the fumes can be removed from the area under the range hood operation panel.When a cook stands or walks in front of the stove,it is likely that the flow of the fumes will be disturbed and the fumes will separate from the suction area of the range hood,and eventually lead to leakage.In order to reduce the external interference suffered by fumes and the leakage of fumes,this research proposes and designs a three-sided air curtain type household range hood to improve the efficiency of the range hood and the ability to resist personnel interference.In this study,a three-sided air curtain range hood experimental platform was built in the lab according to the size and structure of the actual countertop in the kitchen.Based on the conventional wall-mounted flat-panel range hood,a slit outlet is provided on the front and two side edges of the range hood operation panel respectively,so that the airflow from the three sides of the air curtain blows down from the bottom of the range hood and extends to the area below the pot surface.Then it moves up to the exhaust port of the range hood together with the fumes,and is finally discharged outdoors.Based on the air curtain jet theory and preliminary experiments,the ideal target air curtain flow field and fumes flow field are proposed.Through the flow field visualization experiment,the air curtain and fume flow fields under different air curtain jet parameters are observed.From the perspective of flow ratio,the matching relationship between the air curtain jet flow rate and the range hood exhaust volume is calculated,and finally the appropriate air curtain jet flow conditions to achieve the target air flow fields are determined.In order to further study the effects of three-sided air curtain range hood in blocking personnel interference and reducing fumes leakage,under static interference conditions where the humen body model stands still in front of the countertop and under dynamic interference conditions where the humen body model walks in front of the countertop at a speed of 1m/s,respectively,the visualization experiments of fumes flow fields and the measurement of tracer gas concentrations were carried out.Measured and calculated parameters and indicators such as the concentration of the breathing zone,the concentration of the area around the breathing zone,the exhaust gas concentration and the collection efficiency.In this way,the overall evaluation of the effect of the air curtain hood designed in this study on reducing fumes leakage are carried out from the qualitative and quantitative perspectives.The research results show that when the jet angle of the air curtain is 15-30°,the air flow of the air curtain can resist the suction of the range hood without short circuit.The initial jet flow rate of the air curtain should be as small as possible than the exhaust flow rate of the range hood.And under the same initial jet flow,the smaller jet velocity and wider slit width(air curtain thickness)will be more conducive to reducing the degree of air curtain jet entrainment on the fumes,and enable the range hood to discharge the air curtain and cooking fumes in time.A reasonably designed air curtain can effectively block the interference of people standing still or walking in front of the countertop to the airflow of fumes,and reduce the fumes concentration in the breathing zoon by more than 80%.At the same time,the fume collection efficiency when the air curtain is opened is 22% higher than that when the air curtain is not opened.