While geothermal water-cooling systems are becoming known as an energy-saving alternative for residential use, they are still quite novel in plastics processing. Last month’s cover story reported on a cast film extruder that recently discovered the value of this cooling approach, which pulls water at a constant temperature from deep in the earth and returns it—clean—after use. It turns out that custom molder Accu-Mold Plastics in Halifax, Pa. (accumoldplastics.com), has used geothermal cooling for its 19 injection presses for close to a decade. “Our old cooling tower had come to the end of its life and we wanted something more reliable and economical to operate,” recalls v.p. Jack Strohecker II. “Four years ago, our entire facility was destroyed by a tornado. When we rebuilt there was no question about utilizing our existing geothermal system.”
As part of the rebuild, Accu-Mold added variable-frequency drives (VFDs), sensors, and computer controls to the system. “We now have three geothermal chillers and one air-source chiller,” Strohecker states. “The system will add additional chillers as the process loop requires. We have an outdoor air sensor; when the outdoor air temperature reaches a setpoint, say 55 F or lower, the system will then utilize the outdoor air-source chiller—almost like having free cooling, to a point.”
As the geothermal system opens or closes the water supply to the presses and auxiliary equipment, it will see pressure changes and the controller will adjust the VFDs to maintain a preset pressure differential, explains Strohecker. Strohecker says the enhancements to the previous pre-tornado system resulted in energy savings of 38%.