Smaller-Diameter Round Copper Tubes Minimize Refrigerant Volume Compared to Flat Extrusions, Says International Copper Association

New York, NY (May 16, 2011) — The International Copper Association today announced that heat exchangers made using MicroGroove™ copper tubes use less refrigerant than comparable coils made from extruded aluminum tubes with multiple channels. The difference is that the round tubes obviate the large header volume associated with flat tubes. Reduction of refrigerant volume is an important design criterion in today’s environmentally conscious marketplace.

A side-by-side comparison of three prototype heat exchangers was made by researchers at LU-VE S.p.A. in Uboldo, Italy, a major manufacturer of air conditioning and refrigeration products. Stefano Filippini of LU-VE presented the results at a recent IIR Workshop. The three air-cooled condensers had similar cooling capacity, the same frontal areas, and used the same fans.  The prototype heat exchangers were constructed using three tube technologies:

  1. Round inner-grooved copper tubes with diameters of 3/8 inch or 9.52 mm (representing conventional technology)
  2. Special inner-grooved copper tubes with smaller diameters of 5 mm (representing MicroGroove technology).
  3. Special multichannel aluminum tubes with tube dimensions of 30 mm by 2 mm.

Internal tube volumes were greatly reduced for both the smaller-diameter copper tubes and the multichannel tubes, dropping from 5.15 dm3 to 2.41 dm3 and 2.81 dm3, respectively. Notwithstanding, the header volume for the multichannel tubes was 0.91 dm3 compared to only 0.36 dm3 for the other two condensers; hence, the total internal volume was smallest for the 5-mm copper tubes. Hairpin tubes with elbow joints complete the tube circuitry in more compact fashion than the use of bulky headers. (Note 1 dm3 or one cubic decimeter is equivalent to a volume of one liter.)

“This study highlights an important advantage of MicroGroove Technology,” says Nigel Cotton, Global OEM Team Leader for ICA. “MicroGroove uses simple and familiar techniques well-known to manufacturers. The process is flexible and versatile because it does not require investment in complex brazing furnaces, and yet it results in superior products.” For more information on this study or MicroGroove technology, visit

About ICA

The International Copper Association, Ltd. (ICA) is the leading organization for promoting the use of copper worldwide. ICA’s mission is to promote the use of copper by communicating the unique attributes that make this sustainable element an essential contributor to the formation of life, to advances in science and technology, and to a higher standard of living worldwide. Visit for more information about ICA.