COILS, COOLERS AND CONDENSERS
Making the leap to propane- based cabinets with Microgroove
R
efrigeration systems made with 150 grams of propane (R290) have widely proliferated in the past few years. Practically every major manufacture of “reach in” cool display cases now off ers models with propane as a refrigerant. The reasons are not hard to see. With a GWP of three, propane is extremely attractive as an ecofriendly refrigerant. It is aff ordable and readily available.
The phasedown of HFCs by such regulations as the F-gas regulations of the European Union, the SNAP process of the U.S. EPA and the Kigali Amendment to the Montreal Protocol contributed the interest in low-GWP hydrocarbons such as propane.
Although propane is classifi ed as an A3
fl ammable refrigerant, it is safe to use when proper protocols are followed. Propane is not a drop-in replacement. The refrigeration systems must be specifi cally designed for R290 and comply with the charge limit of 150 grams. Currently, a working group within the International Electrotechnical Commission (IEC)
42 October 2017
is developing a standard that would allow for 500 grams of propane to be used in refrigeration systems. If accepted, the new standard could be published in 2018 and as a reference standard it could infl uence standards issued in the U.S., for example by the EPA and Underwriters Laboratories (UL).
It is expected that propane will play a key role in refrigeration systems for many years to come. As MicroGroove tubes and coils are uniquely suited for use with propane, particularly with respect to reduced refrigerant charge, the upsurge in the use of propane will also establish smaller diameter copper tubes in the supply chain and contribute to broader use of MicroGroove technology in all types of refrigeration, air- conditioning and heat pump applications. MTL Cool serves as an example that highlights the transition to propane. Its engineers recognized a golden opportunity to meet a demand for high effi ciency, low-GWP cooling systems using MicroGroove smaller diameter copper tubes.
They recognized two important trends in the refrigeration sector: ■ Progression to smaller diameter tubes for higher effi ciency
■ The use of low-GWP natural refrigerants.
Once the EPA SNAP rules that allowed for 150 grams of propane went into eff ect, the playing fi eld was wide open. The engineers got to work designing the refrigeration systems for supermarket and convenience store applications. They developed a complete line of refrigerated cabinets from scratch, including “reach-in” coolers, with or without glass doors. These cooling cabinets are sometimes sold to the store owners, and sometimes branded and sold to the companies that make packaged goods products. Smaller diameter copper tubes were already being used in the manufacture of residential air conditioning systems. Could the same technology be adapted for use in refrigeration systems using natural refrigerants? MTL Cool had a lot of in- house know-how in the design of process cooling
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