Characterization of Dirt Holding Capacity of Microfiber-Based Filter Media Using Thermal Impedance Spectroscopy

With the development of new classes of high-speed vessels like LCAC, which are expected to ingest high amounts of salt particulates, it is of vital importance to develop a new class of filtration media which can meet this requirement. A microfibrous filter media embedded with nanofibers was thus developed using a nanofiber flocked suspension with a microfibrous support created using traditional wet-lay papermaking methods. While the pressure drop is normally used as the conventional parameter to predict service-life of the filter media, it does not give a proper indication of filter service life. Therefore, a novel thermal impedance technique was applied in this work to characterize the filtration media using thermal parameters via a heat pulse excitation signal. The transient response for the phase lag of temperature was observed because heat transfer occurs during the air flow across the filtration media. The related thermal parameters were obtained through a thermal equivalent circuit model and a nonlinear least-squares fitting algorithm. The thermal impedance method can be used as a filter media diagnostic tool to obtain useful parameters which can be utilized to regenerate filter media and assist to define the operational lifetime of the filter. This can help protect the power systems and reduce the maintenance, operation, and replacement costs. The improved air quality that can be obtained using this advanced filtration technology will enable enhanced protection of engine turbines and other onboard air-breathing systems.