A typical breather consists of an air delivery unit (ADU), a humidifying chamber, a connecting tube and a heated delivery tube. For an effective treatment of several respiratory syndromes such as sleep apnea, the chamber is recommended to generate the required moisture content and temperature of the air delivered by the breather. In this paper a mathematical model is developed for a complete breather with a focus on the humidification process. The model is simulated using Simulink™ in a Matlab™ environment. A series of experiments are conducted on various components of the breather for validation as well as to facilitate the necessary empirical relationships for the simulation process. The main outcomes of this work are: the ADU settings significantly alter the delivered air humidity level; the humidifier settings indirectly control the reservoir evaporation rate by controlling the chamber vapor pressure difference; the heated air delivering tube power input effectively controls the nasal mask airflow temperature; the ambient relative humidity level has a linear relationship with the nasal mask humidity level; and the ambient temperature variation can effectively influence the delivered air conditions.

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