The Effect Of Temperature Field On The Deposition Of Particulate Matter In A Hot Film Gas Flow Sensor

The Hot-film gas mass flow sensor is widely used in the field of gas measurement with its unique advantages.However,the gas in the flow sensor inevitably contains some submicrometer particles due to the working conditions,the performance of filter or other reasons.when these particles move around in the sensor with gas,they could deposit on the Hot-film heating chip,after a long-term accumulation dust stacks will be formed,which can affect the heat transfer of heating resistance and temperature measuring resistance on the Hot-film chip of the sensor and ultimately affect the accuracy of the sensor.There are many factors that affect the particle deposition on the Hot-film chip,such as the installation position of the chip,Magnetic field,Electric field,Flow field,Temperature field and humidity,etc.In this paper,the influence of temperature field on the particle deposition on the Hot-film gas mass flow sensor is mainly studied.The study includes the numerical simulation and the experimental.Firstly,the finite element model of the Hot-film flow sensor is established,and the standard k-? model is mainly used to solve flow field and the temperature field in the Hot-film flow sensor.After obtaining the flow field and temperature field,Lagrange Discrete Phase Model is used to track the trajectories of particles in the Hot-film flow sensor and its final conditions:trapped by wall or escaping through outlet.Finally,the results of particle movements and deposition on the sensor with the effect of temperature field is obtained by calculating the deposition rate of particles with various of diameter under different inlet velocity on the sensor and Hot-film chip when different factors act.The effect of temperature field on the particle deposition on the Hot-film sensor is studied by comparing the changes of particle deposition rate.The enlarged model of Hot-film flow sensor and the producing dust device are designed to verify the numerical simulation results.The result of particle deposition on the Hot-film chip is observed by the stereoscopic microscope.The influence of the temperature field on the particle deposition on the Hot-film flow sensor is studied experimentally with different inlet flow rates.The experimental results is in good agreement with the result of numerical simulation:the temperature field has some influence on the particle deposition on the Hot-film flow sensor under the condition of low inlet flow rate.