Meaning
Measuring the electric power consumed to remove moisture from hygroscopic polymers prior to processing reveals the performance of the drying system. This metric, known as drying energy efficiency, compares the theoretical energy required to vaporize the absorbed water with the actual energy consumed by the dryer. Improving this ratio is a primary method for reducing utility costs in molding operations.
Dryer Design
Desiccant wheel dryers utilize heated air loops that recycle thermal energy during the regeneration cycle. This design minimizes heat loss.
Moisture Control
Hygroscopic resins like polyethylene terephthalate and polyamide require moisture levels below fifty parts per million to prevent hydrolytic degradation during molding. If the drying energy efficiency is low, the system wastes excessive electricity to achieve this target, raising the carbon footprint of the production facility. Optimized airflow and dew-point control prevent such energy waste.
Operational Cost
Operating an inefficient dryer during a continuous production run can double the energy cost per kilogram of processed material. Implementing heat recovery exchangers and variable-frequency drives on blower motors provides a reliable way to optimize energy use. These upgrades reduce operating costs while ensuring that the resin is dry enough to prevent mechanical defects in molded parts.
