How engineered plastic cooling towers are helping to expel heat from laser powder bed fusion 3D printing processes
How engineered plastic cooling towers are helping to expel heat from laser powder bed fusion 3D printing processes. Words by Greg Rankin.
Additive manufacturing (AM) is booming. According to a recent report from Persistence Market Research, the sector is expected to double in size by 2028 to exceed $15 billion. Traditionally, AM consisted of turning plastic resins into prototypes and low-volume parts. Now, the industry is expanding to include a growing list of metals that can be processed on sophisticated 3D printers. However, along with these advances comes a new challenge: managing excessive heat loads.
Utilising plastics in AM requires relatively low temperatures, often under 300°C. With metal, however, the print media can reach temperatures ranging from 1,100-1,400°C. To mitigate the heat, cooling towers are increasingly being employed to cool the process water down. This is exactly the challenge that the GE Aerospace AM facility in Ohio, the US, recently encountered.
“The aviation company was working on a state-of-the-art approach to manufacture aircraft parts utilising laser 3D printers,” says Steve Coppock, consulting engineer at Armour & Associates. The Ohio-based company designs, installs and commissions HVAC and processing cooling systems. “The engineering firm brought us in to help with the cooling system that was required to chill the water used in the processing of these parts.”
HYDRODYNAMICS
From lightweight designs, rapid prototyping, and now increasingly used for low to medium-volume components, AM is still in a fledgling state with an incredible amount of untapped potential.
At the GE Aerospace facility, which has been the focus of important R&D work for the company, the laser printers are used for components that require complex geometries or exceptional precision. While lasers themselves are not hot, the heat produced when the photons come in contact with metals can be significant.
“The facility was looking for a cooling tower that would provide some longevity and would not require a lot of maintenance or repairs,” explains Coppock. “We had been having a lot of success with cooling towers made out of engineered plastic and recommended them for this application.”
Made of high-density polyethylene (HDPE), engineered plastic cooling towers are corrosion-proof, offer exceptional durability, require significantly less maintenance, as well as an easier and quicker installation.
LAUNCH WINDOW
The first tower at the GE Aerospace facility was installed in late 2022 and after a successful debut, a second tower was added a year later to increase production.
“The Delta cooling towers have been a good fit for this facility, and with the 20-year warranty they are covered for the next two decades,” says Coppock.
Delta Cooling Towers pioneered the engineered plastic cooling tower design in the 1970s. The seamless one-piece shell has no joints, seams, panels, gaskets, bolts, fasteners or caulking like conventional towers. The models selected were the Paragon series which each have a cooling capacity of 250 tonnes.
“They really appreciate that that towers are environmentally friendly as well,” adds Coppock. “They don’t require as much water treatment chemical, you lose less water from drift, and your energy savings can be significant.”
INCREASING ALTITUDE
Another issue for any end user looking to add or replace a cooling tower system is the potential noise it generates. At the GE Aerospace plant, the towers are between two buildings which could have created significant echo reverberating throughout the industrial park. To combat the issue of noise, the engineering firm decided it would be best to elevate the towers so that they sit closer to the roofline of the buildings.
“The towers look great sitting up on those platforms, but in hindsight, we may not have even needed to raise them up above ground level because they run whisper quiet,” Coppock explains. “When you’re standing there, literally, the only thing you hear is the water running through.”
The towers also came with variable frequency drives (VFDs) which allow the fan speed to vary so that the units do not run at max RPM except when necessary. Depending on the application, this alone can result in significant energy savings. In fact, an independent report by the New York Power Authority estimated almost a 40% decrease in electrical consumption when using the VFDs on Delta’s cooling towers.
HYPERSONIC SPEED INSTALLATION
HDPE cooling towers can deliver additional cost-saving benefits with a quicker, simplified installation. While getting a typical cooling tower up and running can take several weeks or more, the engineered plastic designs are factory assembled, enabling an installation process that can often be completed in as little as a single day with a smaller crew.
“That installation was basically plug-and-play,” says Coppock. “Don’t get me wrong, there’s some wiring and piping to do, but nowhere near the scale that it takes to put in a stainless steel, galvanised, or even a fibreglass tower for that matter.”
The savings did not end there for GE Aerospace. Coppock estimates that the two new cooling towers have greatly reduced the company’s expenses on costly water treatment chemicals and because they are being well maintained, they have essentially eliminated downtime related to processing temperatures.
