Optimization of the design of a semivolatile aerosol dichotomous sampler

This article reports the results of an optimization procedure for a semivolatile aerosol dichotomous sampler (SADS) and experimental confirmation of the instrument's performance with an optimized sampler. Using numerical model results, the relationships between four major design and operating parameters significantly affecting the performance of the SADS and four performance parameters were expressed in log polynomial equations. Utilizing an optimization procedure, values for the major parameters giving the best performance were determined and used as the base model for optimizing minor parameters. Five minor parameters were then investigated for their possible contribution to better performance of the SADS. The optimal dimensions found were as follows: the diameter ratio between the nozzle and the collection probe was 1.30 and the length ratio of the distance between the nozzle and the collection probe divided by the nozzle diameter was 0.6. Among the minor parameters, only the entrance angle of the nozzle made noticeable improvement at 45. Experimental tests confirmed that the performance of the new sampler was improved although not as much as expected from the numerical simulation.