Design and Evaluation of a Plate-to-Plate Thermophoretic Precipitator

A plate-to-plate thermophoretic precipitator with high particle collection efficiency has been designed and tested_ The precipitator consists of two flat plates separated by a 0_38-mm thermal insulating shim_ The top plate is heated by a constant high-temperature water flow while the bottom plate is cooled by a constant low-temperature water flow_ Through this forced convective heat transfer arrangement, a high and uniform temperature gradient is achieved between the two plates, where submicron aerosol particles can be collected efficiently and uniformly in the direction of the air flow_ The precipitator was tested in the laboratory using l\aCI and sodium fluorescein monodisperse test particles_ When the temperature gradient ranges from 502" to 879°C / cm and the Knudsen number ranges from 0_27 to 3_5, the experimental data show that the present precipitator collects submicron particles efficiently_ Among previous theories, the thermophoretic velocity equation proposed by Talbot et aL (1980) is found to fit very well with the present experimental data_