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Designing a cooling system for a greenfield 264,000-square-foot injection molding facility would always present some difficulties, but doing so in the middle of a desert under water-allocation restrictions posed challenges of a different order. That was the task faced by Process Cooling Systems (PCS), Leominster, Massachusetts, when it was contracted by its long-term customer, Rehrig Pacific, to design and construct a chilled water system for the company’s newest injection molding facility outside of Phoenix in Buckeye, Arizona, featuring presses ranging in clamp force from 1,000 to 4,000 tons. The maker of returnable and reusable containers for waste, recycling and supply chain logistics broke ground on the new factory in May 2023. Sitting on 35 acres, the facility has room to double its footprint and is outfitted with full air-conditioning, smart dock controls, 380-KW solar panels and EV charging stations.

Rehrig Pacific’s new 264,000-square-foot plant is in Buckeye, Arizona, southwest of Phoenix. Source: Rehrig Pacific

In the initial design phases, Rehrig Pacific sought ways to conserve water and reduce power consumption at the facility and, in doing so, quickly realized that installing a traditional evaporative plant cooling system and standard chillers for its injection molding machines wouldn’t be an option.

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PCS’ solution was to engineer an all-air-cooled chilled-water system that uses substantially less water than traditional designs while efficiently utilizing and often reducing the required electrical consumption. That was accomplished by applying variable frequency drive (VFD)-managed pump loops at point of use. “Reducing consumption is important to our company sustainability values and goals,” explains Dan Fiscus, project engineer at Rehrig Pacific, “but we also had to meet local demand requirements, and this solution is a game changer.”

Unlike Rehrig Pacific’s other facilities, the Buckeye plant could not use a centralized cooling tower or adiabatic cooling system to provide machine cooling and chiller condenser cooling for water-cooled chillers because that setup would have exceeded the allowable water allocation for the site. PCS’ answer was to employ high-efficiency, air-cooled chillers with variable-speed compressors on a system designed with a low-pressure, variable-primary flow loop circulating water through the chillers and out to the machines. As part of the innovative system, individual PLC controls were placed at every machine, designed to optimize flow and temperature for mold and machine cooling.

Individual PLC controls at every machine optimize flow and temperature for mold and machine cooling. Source: Process Cooling

This design also reduced the initial equipment and system installation investment by Rehrig Pacific, by not only minimizing the equipment needed but also reducing the interconnecting system piping required and the size of the mechanical room. It also eliminated the centralized machine cooling process piping, as well as lowering the size of the chilled water process piping used for mold cooling. In processing, the higher flow rates and individual control at each mold lowered cycle times and improved part quality. In addition, the costs associated with water use, chemical treatment and water discharge for this facility were either eliminated or significantly reduced.  

Rehrig Pacific and PCS have partnered on projects for more than 35 years, with PCS providing full systems and equipment for various Rehrig Pacific plant expansions over the decades. Rehrig Pacific National Project Engineering Manager Matt Rutigliano and his team worked in full collaboration with PCS to design the Buckeye plant’s cooling system. “Our companies align very well in terms of values and culture,” Rutigliano says. “We are both family-owned with an established group of dedicated and long-standing employees who really care and take the time to engineer the right solution.”