With global temperatures and the incidence of regional heat waves rising, the heat is on to develop and deploy cooling systems with improved efficiency. U.S. Pacific Northwest National Laboratory engineers are advancing adsorption cooling systems that require only small amounts of waste heat from a building or industrial plant to power reactions between a vapor refrigerant and a solid material.

Without the need for a compressor or regular energy inputs, refrigerant-based adsorption cooling technology eliminates the cost, efficiency and reliability issues that have impeded adoption of current water-based adsorption cooling systems for commercial and residential use.

The researchers tested a series of pore-engineered metal-organic frameworks to determine how well they pair with a common refrigerant, the fluorocarbon R134a. This hydrofluorocarbon refrigerant has a high global warming potential but a similar chemical behavior to the more environmentally friendly hydrofluoro-olefins (HFOs), making it a suitable alternative for studying the molecular interactions of adsorption cooling systems that will use HFOs in the future. Unlike hydrofluorocarbon refrigerants that will be phased out in the next few years, HFOs have a global warming potential near zero.

The research published in Accounts of Chemical Research outlines how the chemistry between the refrigerant and solid sorbent materials in an adsorption cooling system can be fine-tuned to affect its cooling capacity and energy efficiency.