The air-conditioning industry may be able to cool using a new refrigerant and increase efficiency, but not increase the system’s size, according to new research from the ARTI.

The newly released Air-Conditioning and Refrigeration Technology Institute report explains how flattened-tube heat exchangers, in place of traditional round-tube heat exchangers, function under various environmental conditions and pressures.

“Flattened-tube heat exchangers have received much attention as a possible replacement to traditional round tubes, but until now little research has been done on the thermal-hydraulic performance of flattened tubes under wet, dry and frosted conditions,” said Elizabeth Jones, a project manager with the institute, which provided the funding for this project under its HVAC&R Research for the 21st Century program.

The report explains how a flattened tube, compared with the traditional round-tube heat exchanger, allows for improved heat transfer and thermal performance; increases coil and overall efficiency; reduces refrigerant charge; and reduces coil size.

In the report, University of Illinois researchers provide analysis, modeling and interpretation of thermal-hydraulic performance for flattened-tube heat exchangers under wet and frosted surface conditions.

They also make design recommendations to help improve the performance of plain, wavy, strip and louvered fins for flattened-tube heat exchangers. A full assessment of such heat exchangers is also included.

To read the final report, “An Assessment of the State-of-the-Art and Potential Design Improvements, for Flat-tube Heat Exchangers in Air-Conditioning and Refrigeration Applications,” visit .