Numerical Simulation And Characteristics Analysis Of Variable Pressure Exhaust System In High-Rise Residential Kitchens

With the development of economy and the advancement of urbanization,high-rise buildings will be the developing direction of the future.High-rise residential buildings exhaust kitchen smoke through concentrated flue.Although this method solves the problem of random emission of flue gas,it also brings problems such as backflow of smoke and exhaust imbalance.For this reason,this paper carries out the following research.First of all,the principle of backflow of smoke and the principle of dynamic and static pressure conversion are analyzed theoretically,and the ratio of variable pressure section is derived.The theoretical analysis is tested by experimental research and the CFD numerical simulation is used for further analysis.The conclusions are as follows: When flue gas is discharged from the range hood of adjacent floor,the floor of the unopened machine will not have the smoke of backflow,and there is a certain amount of natural exhaust volume.The static pressure at the branch flue decreases with the increase of exhaust smoke volume of the other two layers.The natural exhaust volume increases with the increase of exhaust smoke volume of the other two layers.Secondly,taking 10,20,and 30 layers of variable pressure flue duct as the research object,the influence of opening distribution,opening rate,and hot pressure on the distribution of static pressure in the flue and the system's smoke emission were analyzed.The conclusions are as follows:Whether it is evenly open or centralized open,the higher the open rate,the greater the static pressure in the flue,the smaller the smoke discharge,and the worse the system exhaust equilibrium.Whether it is evenly open or non-uniform open,the opening distribution has little effect on the amount of smoke exhausted and the degree of exhaust smoke balance.When the opening rate is 1.0,the static pressure shows a low-high-low distribution from the bottom layer to the top layer,but the distribution of the smoke volume is a high-low-high distribution,and the maximum static pressure and the minimum amount of smoke are all located at the height of 1/3.When considering hot-pressing,the amount of smoke in each layer is slightly more than that without considering heat pressure.Hot pressurehas little effect on the degree of exhaust smoke balance,and nor does it change the distribution of static pressure and smoke volume.Finally,the influence of the performance of the cooker hood on static pressure in the flue and the system's smoke emission were analyzed,the reasonable wind pressure of cooker hood is determined,and the optimization strategy of vertical dynamic zoning based on the distribution of exhaust volume and the distribution of static pressure is put forward for the variable pressure flue system.The conclusions are as follows:When the air volume changes,the range hood with a wide range of whole pressure,the system exhaust gas equalization is better.The wind pressure does not affect the static pressure distribution in the flue and the distribution of smoke emission in the system,but the greater the wind pressure,the greater the smoke volume and static pressure.For the flue in this paper,when a single power source is selected,the 10,20,and 30 layer flue with the cooker hood of 100 Pa,130Pa,and160 Pa respectively can meet the reasonable range of exhaust smoke.The dynamic zoning does not change the law of static pressure distribution in the flue,the more the number of partitions,the better the balance of the system is better.For the 30-story flue,after the four-segment partition,the degree of unbalance was 66.8% lower than when it was not partitioned.For the20-story flue,after the three-segment partition,the degree of unbalance was 57.5% lower than when it was not partitioned.