National Institute of Standards and Technology (NIST) researchers have developed a testing apparatus that uses a high-resolution camera to track—with laser-illuminated dust particles—the motion and distribution of air flow in finned-tube heat exchangers.

Data from these highly accurate laboratory experiments are being compared with computer simulations of air flow performed with computational fluid dynamics (CFD) software. Once accurate CFD models are developed and validated, engineers could use them as the basis for design changes to coil assemblies and refrigerant circuitries to accommodate the existing air distribution. The NIST program, partially sponsored by the Air-Conditioning and Refrigeration Technology Institute (ARTI) under a Cooperative Research and Development Agreement (CRADA), could increase finned-tube heat exchanger heating or cooling capacity by five percent, resulting in improved heat pump efficiency.

Additionally, such improvements could allow manufacturers to reduce the heat exchanger size, thereby reducing material cost and the amount of refrigerant needed. According to the organization’s press release, the NIST study results on home air-source heat pumps will be issued in 2009 and are also expected to be applicable to large heat exchangers used in commercial buildings and refrigeration systems.