In vivo measurements of human oral cavity heat and water vapor transport

Oral heat and water vapor transport may play a significant role in maintaining airway health. This study intended to develop a technique for measuring heat and mass transfer coefficients in the human oral cavity as a function of flow rate. A multi-thermocouple probe was developed which simultaneously measures dry and wet bulb temperatures at two airstream sites while also measuring three buccal wall temperatures. Oral temperature data (airstream and buccal surface) were acquired from eight subjects (two females and six males) breathing at varying flow rates to calculate transport coefficients. Techniques used to validate probe accuracy included correlating experimentally measured heat transfer in a smooth pipe with theoretical plug flow in a circular conduit. Experimental results suggest that modeling the oral cavity as a circular conduit is problematic because Nu measured in a heated pipe differs so greatly from Nu measured in the oral cavity.