Numerical evaluation of the convective and radiative heat transfer coefficients for preterm neonate body segments inside an incubator

Thermoregulation and bioheat models for preterm neonates are used to study heat transfer inside infant incubators. These models need anatomically specific radiation and convection heat transfer coefficients for different body segments. In the present study, numerical simulations are performed for a preterm neonate consisting of 5 body segments (head, arms, trunk, back and legs) placed inside an incubator. The studies are conducted for varying incubator inlet temperature ranging between 29 and 35 °C and different air flowrates between 5 and 50 L/min. It is found that the heat transfer process depends mainly on the incubator air temperature. Meanwhile, it is shown that the incubator air flow rate does not affect significantly the convective heat transfer process. Thus, it is concluded that the heat transfer between the incubator air and the infant skin is caused by natural convection. The effect of the flow structure on the temperature distribution is studied and correlations for the radiative and convective heat transfer coefficients are obtained for each body segment. The radiative heat transfer coefficient varies between 2.2 and 6.2 W/m2K while the convective heat transfer coefficient varies between 2.6 and 4.7 W/m2K. The results are validated against experimental data from the open literature. A thermoregulation model is also developed taking into consideration heat and mass losses due to skin evaporation and respiration. This model is used to quantify the heat balance in preterm neonates.