Challenge

A heated airflow stream was required for a medical manufacturing process, with heating provided by an in-line coiled electrical element. The system required tight temperature control while maintaining the necessary airflow. The heating element therefore needed to be sized to provide the required heat transfer without introducing excessive pressure loss.

Engineering Approach

Mathematical models were developed to predict both the heat-transfer and pressure-loss characteristics of the in-line coiled heating element. Established empirical correlations were incorporated where appropriate to improve confidence in the analytical predictions. The analytical results were then used to inform a detailed CFD study of the heater and surrounding ductwork, examining airflow distribution, heat transfer and pressure loss. The combined analytical and numerical results were used to determine the required heating-element and duct geometry.

Outcome

The heating element and duct system were designed and sized from the analytical and CFD predictions – there was close agreement between the analytical and CFD predictions. The system was subsequently prototyped and tested, with its measured performance closely matching the predicted behaviour.