The next time you enjoy a cold brew, consider whether the condensers used for process cooling at the brewery are made with smaller-diameter copper tubes.
Modern turnkey refrigeration systems from one refrigeration system supplier use smaller-diameter copper tubes in the condenser. These chiller systems are put to work in breweries to cool wort, control fermentation and chill conditioning tanks. One chiller system with grooved condenser tubes offers improved performance in a smaller footprint compared to coils made with larger-diameter copper tubes or aluminum microchannel.
Tommy Gaubatz of Innovative Cooling & Equipment Inc. (ICE) recognized that the grooved condenser tubes could serve as a “game changer” for the large condensers used in process cooling and commercial refrigeration. Dubbed Microgroove, the small-diameter copper tubes are manufactured with proven, cost-effective copper fabrication processes and familiar assembly techniques.
Having spent much of his career at Carrier in various marketing and engineering roles, ICE’s Gaubatz had witnessed the move toward smaller-diameter copper tubes in both residential air conditioning as well as refrigerated transport. He realized that smaller-diameter copper tubes offered advantages in the design of process cooling equipment as well.
Gaubatz teamed up with Pro Refrigeration, Auburn, Wash., a company with extensive experience in building industrial-sized refrigeration equipment. Along with the engineers at Pro Refrigeration, Gaubatz helped to apply ICE’s new condenser constructed with smaller-diameter copper tubes. This condenser turned out to be a perfect fit for the process cooling systems that Pro Refrigeration builds for breweries.
Perfecting the Design
The new refrigeration system first went on display at the 2016 AHR Expo in Chicago. ICE designed and assembled the condenser module with 0.197” (5 mm) copper tubes for Pro Refrigeration’s process chiller. Already, the first Pro Refrigeration system using the small-diameter grooved tubing has been installed, and more are being built for breweries across the country, notes Jim Vandergiessen, CEO of Pro Refrigeration.
While it is true that a large cooling system requires a large surface area to exchange heat with the ambient air, the refrigerant tubes need not have a large diameter. In fact, smaller-diameter tubes allow for a more compact design. The higher heat-transfer coefficients of the smaller-diameter tubes allow for heat to be transferred more efficiently from inside-the-tube refrigerant through the tube wall and ultimately to the fins on the airside of the condenser.
Gaubatz designed the condenser to minimize pressure drop with shorter overall circuit lengths. The design also alleviates most of the stress due to thermal expansion. Another advantage is that the heat exchanger modules are flexible, light, compact and easy to install.
Using this atypical design configuration, the condenser system could be fitted to the high side of the air-cooled process chiller. The result was a smaller footprint than could otherwise be achieved with large-diameter-tube condenser configurations.
The design of the condenser also resulted in less refrigerant. For a brewer, the cost of refrigerant could be a significant fraction of the total system cost, says Gaubatz. This factor becomes even more important as new, more costly refrigerants are developed.
The use of smaller-diameter copper tubes can reduce the amount of refrigerant in the system by several hundred pounds. For example, a system using large-diameter copper tubes might require 700 pounds of refrigerant while a similarly sized system using smaller-diameter tubes might use only 200 or 300 pounds of refrigerant.
“When refrigerant sold for a few dollars per pound, these costs were manageable,” says Gaubatz, “but as the price of new refrigerants climbs to $10 or more per pound, it becomes a big deal.”
Gaubatz preferred MicroGroove copper over aluminum microchannel coils for a number of reasons. One reason was that none of the microchannel coils available would fit his design requirements. Also, he preferred copper tubes because they are proven technology and contribute to better system reliability.
According to Gaubatz, corrosion in microchannel coils could result in a catastrophic system failure. Such failures are especially troublesome because the coils cannot be easily repaired in the field. Ultimately, corrosion-resistant coatings were developed, but these added costs to the coils. In nearly all applications where microchannel is used —and especially in mission-critical process cooling applications — such coatings are mandatory when using aluminum-only coils.
Meeting the Needs of Brewers
Process cooling at the brewery is mainly needed for rapid cooling of the wort. As every zymurgist knows, wort is a key intermediate ingredient obtained from boiling crushed hops in a malt extract. The carb-rich wort is cooled rapidly and precisely held at various temperatures. Yeast is added, and fermentation occurs at these set temperatures.
Temperature control is paramount to successful brewing. Process cooling is accomplished using a chilled mixture of glycol and water. A stainless steel sanitary heat exchanger employs a counterflow of chilled coolant to cool the wort.
Coolant can be pumped to cool the wort in a precisely regulated process. Once it picks up heat from the wort, it is pumped to the outdoor refrigeration system and then stored in tanks that typically hold 2,000 gallons.
Pro Refrigeration makes turnkey refrigeration systems specifically for breweries. The outdoor system is a complete package: the condenser rests atop the evaporator. This system functions more or less as a chiller except that the circulated liquid is a glycol-water mixture rather than just water.
Gaubatz cooperated with coil makers in the optimization of the coil designs. Typically, coil makers assist in the design of the coils. ICE has used heat exchangers coils from Super Radiator Coils as well as Lordan. “The technical service offered by both companies has been excellent,” says Gaubatz. “I would not have been able to develop these condensers without a robust supply chain in place.”
The ICE design incorporates many features that Gaubatz feels will provide exceptional performance — not only in refrigeration systems for breweries but also in other process cooling and commercial refrigeration applications.
“Right now, the ICE condenser can outperform any microchannel condenser,” he asserts. “With further optimization of the coil design and improvements in manufacturing, I believe that smaller-diameter copper tubes will be the winning technology for most process cooling applications that rely on an outdoor condenser.” PC
To learn more about process cooling refrigeration systems from Pro Refrigeration, Auburn, Wash., utilizing small-diameter grooved copper tubing, call 253-735-9466 or visit www.prochiller.com.