Simulation And Improvement Of Commercial Kitchen Exhaust Hood

Exhaust hood is generally used in modern kitchen to discharge cooking fumes and heat to keep a good quality of indoor air and provide a healthy work environment.It also plays a part in filtration and purification of grease in exhaust air to decrease air pollution when cooking air is directly exhausted to outside.Required air flow rate will be changed with fumes volume during cooking.The more air flow rate,the more pressure loss will be produced when the air goes through the exhaust plenum,especially in Chinese cooking with heavy oil.That will have a negative effect on exhausting performance.Base on a good purification efficiency of cooking fumes,how to decrease the pressure loss is a very important factor in exhausting performance improvement.Combining with the requirement of Chinese market,a foreign brand exhaust hood which has big domestic sales is chose for research.It has a prominent performance on fumes exhausting and grease purification in light oil cooking.But in Chinese cooking with heavy oil,energy consumption is greatly increased because of too much pressure loss producing due to the increase of air flow rate.It also cannot meet the requirement of grease purification efficiency and need to be improved.Firstly exhaust plenum of hood need to be simplified according to the feature of numerical simulation.Then flow channel model can be created based on the simplified exhaust plenum and meshed.The correlation between flow field parameters such as pressure,velocity,turbulence situation of exhaust plenum and pressure loss,grease purification efficiency can be got from analyzing the feature of flow field distribution in flow simulation.The area which produces much pressure loss can be improved and purification efficiency also can be reduced.Comparison with the new and old simulation results shows that it is obvious in improving pressure loss and grease purification efficiency.Secondly an experimental model is made to test flow field parameters by tuft method and Pitot tubes to verify the correctness of simulation results and validity of improving project.Finally the new product with improved structure is used to have a test by Administration of Quality Supervision in Environmental Protection Products to find it completely in conformity with Chinese requirement.It is further proved that the improved project has validity and feasibility.