Simulation of Heat and Mass Transfer Processes in a Surrogate Bronchial System Developed for Hygroscopic Aerosol Studies

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Abstract
In order to study quantitatively the behavior of inhaled hygroscopic aerosol particles, a surrogate tracheobronchial system, capable of simulating the in vivo atmosphere (i.e., temperature and relative humidity) in a physiologically realistic manner, was developed and is reported here. This surrogate tracheobronchial system is a tubular, multicomponent physical model in which the average Reynolds number value for the airflow within each respective compartment, or section, equals the value within the corresponding bronchial airway generation of Weibel's Model A network. The mass transport phenomenon (i.e., the in vivo water flow through a tracheobronchial wall and its membrane, and subsequent water evaporation into inhaled air) was simulated using this system. Detailed information regarding localized air temperature and water vapor concentration patterns for the steady flow rate of 13.5 L/min is reported in this work. The impact of the laryngeal simulator was studied, and average values of Nusselt and Sherwood numbers for each bronchial generation are reported. These values were lowest downstream from the laryngeal simulator. The in vitro temperature and water vapor concentration patterns and transfer coefficients will be used in a future quantitative analysis of the dynamic behavior and deposition rates of hygroscopic aerosol matter.