By Josh Perry, Editor
[email protected]

Researchers from the U.S. Department of Energy (DOE) Pacific Northwest National Laboratory (PNNL) in Richland, Wash. reported high levels of adsorption using a metal-organic framework (MOF) and a common refrigerant, according to a report from the lab.

PNNL researchers have demonstrated high adsorption levels using MOF and a common refrigerant. (PNNL)

PNNL researchers have previously worked with MOF, porous compounds that adsorb refrigerants, to build adsorbent cooling systems but this is the first test with fluorocarbon R134a, which is a common refrigerant.

“They tested five types of MOFs,” the article explained. “All five displayed very high R134a saturation capabilities, but one in particular—the zirconium-based NU-1000—showed exceptional fluorocarbon uptake, adsorbing 170 percent of its weight, one of the highest values yet seen for MOFs. The results show promise for developing smaller cooling units that use less refrigerant, which could help save costs and lower greenhouse gas emissions.”

While fluorocarbon R134a has replaced chlorofluorocarbons to avoid damaging the ozone layer, they are still greenhouse gases, so this research is an important breakthrough for more efficient and environmentally-friendly air conditioning systems.

The research was recently published in Applied Energy Materials. The abstract stated:

“Through solar, wind, or geothermal reallocation sources, heat transformation via adsorption-based systems provides the means to address the high energy global demand from refrigeration and cooling. However, improvements toward a suitable, high performing adsorbent–refrigerant working pair must be made to boost the applicability of such systems.

“For the first time, a series of mesoporous metal–organic frameworks (MOFs) have been tested for R134a fluorocarbon adsorption for this purpose. Each of the selected MOFs exhibit excellent, reversible R134a adsorption. Among them, NU-1000 provided an exceptional fluorocarbon uptake of ∼170 wt % near saturation, which is among the highest values reported so far for MOFs.

“Exhibiting appropriate equilibrium isotherm behavior and working capacities as large as 125 wt %, it is evident that mesoporous MOFs—especially those with hierarchical structure—are promising candidates for chiller applications. Such high-performance materials provide significant potential for the design of future adsorption cooling systems.”