Chillers think plant-wide for energy savings
When it comes to saving energy with chillers, it's important to realize one thing from the start: treat it like a piece to a puzzle."There's no single magic bullet to achieve an energy efficient chilling system," said Don Berggren, president...
When it comes to saving energy with chillers, it’s important to realize one thing from the start: treat it like a piece to a puzzle.
“There’s no single magic bullet to achieve an energy efficient chilling system,” said Don Berggren, president of Berg Chilling Systems. “Instead, the process requires a plant-based approach that looks at the whole picture.”
Why isn’t it as simple as just buying energy efficient chillers? “From an energy efficiency perspective, chillers haven’t progressed much over the years because the focus has tended towards reducing ozone-depleting refrigerants, not cutting energy consumption,” said Ziggy Wiebe, owner of Chillers Inc.
Achieving energy savings with chilling systems is difficult, then…but not impossible. Luckily, operating in a northern country like Canada gives processors an opportunity right off the bat: free cooling, which is the use of “free” lower external ambient air to assist–or bypass entirely–the mechanical cooling systems during winter months.
THE JOY OF FREE COOLING
“Free cooling of a chilled water system during winter and even into part of spring is an effective way to cut power consumption,” said Don Berggren. “In a regular cooling system, chilled water loops cooled by mechanical refrigeration operate continuously. Using free cooling, refrigeration compressors can be turned off in the winter to save energy.”
It gets better: Many newer models combine a central chiller and outdoor free cooling in one unit to allow process cooling water to bypass the chiller when outside temperatures are low enough.
The potential of free cooling can best be realized when combined with variable frequency drives (VFDs), which can be installed to reduce fan/pump motor speed to 80 per cent full speed, in turn reducing a cooling system’s energy consumption by as much as 50 per cent. “VFDs are important in allowing motors to run at a lower speed, which saves energy usage,” said Balbir Anand, vice president of Freeze Co. Systems. “There’s a cost to installing VFDs, of course, but processors usually find that it will be paid back relatively quickly.”
The only real drawback to free cooling is–you guessed it–temperature fluctuations. “If the weather isn’t conducive, free cooling won’t provide much in the way of energy savings, particularly when temperature fluctuations cause energy spikes,” said Don Berggren. “The differing demands of each manufacturing system play a role here: Processors who are running molds at lower temperatures will have shorter periods of time to take advantage of free cooling than will those with higher mold temperatures.”
HEAT RECLAIMING AND BEYOND
A second energy saving strategy is heat reclaim. In a traditional chilled water cooling system, heat is transferred from the indoor coil to the outdoors. “Not only is this heat wasted, but energy is consumed at the cooling tower and condenser-water pumps in the process,” Ziggy Wiebe said.
Whether or not a heat reclaim system is feasible for your shop boils down to whether or not it can accommodate continuous and peak hot water demand while still providing a controlled source of service hot water. If so, a heat reclaim system might be a valueable energy saving addition. A way to further build on these savings is to include a heat reclaim chiller, a device that generates high-pressure refrigerant that can be used to produce higher temperature condenser water.
And although it sounds obvious, proper sizing and application of equipment shouldn’t be overlooked– but often is. “Too many chilling systems are oversized, resulting in higher than necessary power and energy consumption per ton of cooling delivered,” said Henry Van Gemert, president of Regloplas Corporation. “By better matching current loads with chiller units, processors can get better performance and energy efficiency.” Modular chillers are particularly well suited for this; they can be installed in hard-to-reach places, require a only small footprint, and make it easier to better match current and future cooling demands.
Other recent chiller technical developments can also help. Piovan’s new PET chiller, for example, is designed for energy efficient performance for chilled water systems. Developed for PET perform production lines, the unit is equipped with inverter controlled compressors for self tuning of the refrigeration capacity necessary to provide cooling to the utilities.
Another energy efficient technical development is Advantage Engineering’s new Maximum portable chillers with digital scroll compressors. Combined with Advantage’s proprietary control, the digital scroll compressor modulates cooling capacity from 20 to 100 per cent, while also consuming less energy than traditional portable chillers that use hot gas bypass capacity control. “Portable chillers are often applied to a wide range of load profiles, making energy efficient capacity control an important feature,” said Ziggy Wiebe.
It doesn’t hurt to reiterate that these developments remain a piece of the bigger puzzle. “In the end, a processor has to be prepared to examine its entire process and make changes anywhere in the system to get the best cooling efficiency,” Wiebe noted.
Advantage Engineering Inc. (Greenwood, Ind.); www.advantageengineering.com; 317-887-0729
Chillers Inc. (Newmarket, Ont.); 905-895-9667
Berg Chilling Systems Inc. (Toronto); www.berg-group.com; 416-755-2221
Freeze Co. Systems Limited (Brampton, Ont.); www.freezeco.com; 1-800-339-8982
Piovan Canada Ltd. (Mississauga, Ont.); www.piovan.com; 905-629-8822
Regloplas Corporation (St. Joseph, Mis.); www.regloplasusa.com; 1-888-799-4110
Plastics Machinery Inc. (Newmarket, Ont.); 905-895-5054
Quebec Processor gets “Air Blast,” Energy and Water Savings
A major plastics processor in Quebec had to satisfy a temperature requirement within the range of 7° to 25°C with chilled water cooling. Looking to trim energy costs, they determined that most of the load could successfully operate at higher supply temperatures, which would allow the majority of the load to be satisfied by ambient-produced cooling rather than high horsepower mechanical cooling. As a result, they calculated that only 22 per cent of the load would require a chiller supplying mechanical cooling at 7°C, while the balance–78 per cent–could be satisfied with cooling at 30° to 35°C.
The most energy efficient solution, they realized, would be to utilise ambient-based cooling equipment, and the most environmentally friendly solution would be a sealed air blast fluid cooler that consumes no water. Also, there would be no evaporative cooling requiring water make-up as required by an evaporative cooler, no need to introduce water for temperature trimming, and no need for the constant attention of chemical treatment. Problem was, such a system wouldn’t be able to attain and maintain the lower temperature requirement during the hot summer months. To meet the 7°C requirement, they knew, a chiller would have to be used in conjunction with the fluid cooler.
The processor contacted Berg Chilling Systems. Berg supplied an Eco-Wise system that integrated both the air blast cooler and a chiller. Equipped with Berg’s Eco-Trol controls, the system automatically allows for a transfer between the air blast cooler and the chiller. The air blast cooler satisfies the process demands for most of the year– even taking advantage of cooler sp
ring and fall nights– while the chiller takes over to supply the portion of the process that requires 7°C when ambient temperature rises above 2°C.
The customer now stands to save approximately $100,000 annually through reduced energy and municipal water usage and chemical treatment savings. The system payback? Less than two years.
The Race to Replace R-22
For chiller manufacturers, 2010 represents the dawning of a new age: effective January 1, the industry’s most widely used refrigerant–R-22–was history. Under the terms of the Montreal Protocol, it’s now illegal to make, import or sell chillers in Canada and the U.S. that use R-22.
With process cooling’s across-the-board standard gone, the onus is on equipment suppliers to come clean with their customers. “The fact is, we don’t know which replacement refrigerant will come out on top, if any,” said Don Berggren, president of Berg Chilling Systems. “For this reason, we direct our clients to choose the refrigerant that best suits a particular application.”
With this caveat in mind, here’s a quick look at three leading R-22 replacements.
THE FRONTRUNNER: R-410A
The early favorite to replace R-22 has to be the non-ozone-depleting R-410A. “The largest compressor manufacturer in the world, Copeland, is saying that R-410A is the refrigerant they’ll use in their digital scroll compressors,” said Ziggy Wiebe, owner of Chillers Inc. Chiller manufacturers such as Advantage Engineering, for example, have already released new chiller models–in this case the Maximum portable waterchiller–that use R-410A, as has Thermal Care with its’ NQ line of air-cooled portable chillers, and Mokon with the new Iceman portable and central chillers.
SECOND PLACE: R-134A
Not so fast, however. “Because R-410A operates at significantly higher pressures than R-22, many components must be more robust than is standard in conventional chillers.” said Balbir Anand, vice president of Freeze Co. Systems. “Also, R-410A can’t be used to retrofit existing R-22 equipment, due to significantly high operating pressures By comparison, the low-pressure R-134A refrigerant can replace R-22 with minimal adjustments to the chiller.” In addition to Freeze Co., another manufacturer embracing R-134A is The Conair Group: The company’s EarthSmart portable chiller product actually uses both R-134A and R-410A refrigerants.
THIRD PLACE: R-407C
Another alternative to R-22 is R-407C. “We’ve standardized on the R-407C, which has been very popular in the European chilling industry for some time,” said Henry Van Gemert, president of Regloplas Corporation. The company’s air-and water-chilled Reglochill units, for example, use R-407C, as do larger chillers offered by Advantage Engineering.