High Flow DMA:
Producting high thoughput of size selected nanoparticles
Polydispersity is a problem when using gas-phase processing for the synthesis of nanoparticles.
Producing size-selected nanoparticles at higher rates is possible by using higher flow rates of the carrier gas, made possible by specially designed High Flow Differential Mobility Analysers (HFDMA). These have been designed and tested by the research group of Prof. Einar Kruis at the University of Duisburg-Essen.
In the figure below the performance in terms of the attained geometric standard deviation (GSD) is shown for a HFDMA operating at aerosol flow rates up to 8 slm (MFDMA), available in a (exchangeable) short and long version. The aerosol to sheath gas flow ratio is indicated in the caption.
High Flow DMA has the same fundamentals as DMA. The main differences are related with the high flow rates used in the sheath gas and in the aerosol gas. High Flow DMA is able to work with higher flow ranges.
The first experiments demonstrating the performance of the short and long High Flow DMA have been done. The aerosol flow rate varied between 1.5 to 8 L/min. The ratio of aerosol to sheath flow was varied from 1/10 to 1/5 and to 1/3. The aerosol flow was measured continually and the sheath gas circulated in a closed loop.
In figure to the left, an even larger HFDMA capable of handling aerosol flow rates up to 500 slm and sheath flow rates up to 1500 slm is shown. Also a graph of the attained geometric standard deviation with a sheath flow rate of 1500 slm and various aerosol flow rates is shown below.
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