Research of a Cavity Dust Sensor Based on Source of β Particles

One passive cavitied dust sensor based on βparticle source was designed for continuous and real-time measurement of pipeline dust concentration. A flat cavity structure was used in the sensor, and experiment in the environments with static windless and wind tunnel, then the software ANSYS fluent 15.0 was used to simulate the internal flow field of the sensor to optimize the structural parameters of the sensor (area of air inlet port, source area and source-collector spacing, etc.). The influence of ambient temperature and humidity conditions on the sensor response was investigated by using a self-made temperature adjustment box and a humidity adjustment box. The wind tunnel with specific parameters (temperature 30～33℃, humidity ratio 1%～2%, wind velocity (9.7±0.2) m/s) experiment was used to investigate the sensor response to the different dust concentrations. This study thus indicates the sensor response changes nearly 50% when the temperature changes from 34℃ to 233℃; the sensor response changes nearly 30% when the humidity ratio increases from 6.52% to 10.65%; and at low humidity and low temperature in the wind tunnel, the output signal of the sensor was 16.6, 30.4, 38.1, 45.3, 53.2 mg•m^-3, corresponding to the sampling concentration of the filter 13.5, 26.8, 33.6, 47.5, 63.3 mg•m^-3, respectively. The feasibility of the measurement principle was verified by the experiment results. The preliminary relationship between ambient temperature and humidity and the response value of the passive dust sensor with β particle source was obtained. The deviation of dust concentration measurement caused by the change of temperature and humidity should be further investigated.