HVAC filters clogging detection using electrospun sensory membrane

Clogged air filters increase pressure drop, thereby raising energy consumption in HVAC systems. Monitoring this pressure drop enables real-time detection of clogging. This study focuses on developing a TPU membrane designed for strain sensing to be used as a pressure drop sensor in ventilation systems. TPU nanofiber membranes were electrospun into a honeycomb structure to minimize the pressure drop caused by the sensor itself, with a carbon sensor ink printed in a zigzag pattern to enable signal detection. Structured collectors with porous honeycomb patterns were used during electrospinning to create these honeycombed membranes. The effect of honeycomb hole size (0.5 cm and 1.5 cm, with corresponding membranes labeled TPU-0.5 and TPU-1.5) on electrical resistance and pressure drop was assessed in a lab-scale ventilation tunnel at various airflow velocities representative of those used in Heating Ventilating and Air Conditioning (HVAC) systems. The TPU-0.5 membrane showed higher sensitivity (∆R/R up to 28%) but resulted in a significantly higher pressure drop compared to the TPU-1.5 membrane (134.3 ± 7.6 Pa vs. 34.0 ± 2.4 Pa at 3.83 m/s). Cyclic testing revealed resistance drift, indicating the need for stabilization cycles to ensure consistent results. The findings indicate that the TPU-1.5 membrane achieves a better balance between sensitivity (10-15% resistance change at 3.83 m/s of velocity) and pressure drop (maximum 32-38 Pa at 3.83 m/s of velocity), making it more suitable for real-world applications in air handling units, particularly for monitoring filter clogging.