Adsorption characteristics and cooling/heating performance of COF-5

Adsorption-driven heat pumps (AHPs) powered by low-grade waste heat and solar energy are promising to reduce the energy consumption for cooling and heating. Seeking novel high-performing adsorbents of AHPs is the key to improve their cooling/heating performance. Very recently, the potential use of covalent-organic frameworks (COFs) adsorbents of AHPs has won increasing research interests. However, the adsorption cooling/heating performance of COFs under varying working conditions is still unexplored. In this study, COF-5 was synthesized and tested to obtain the adsorption isotherms of ethanol working fluid. For comparison, three commonly used metal-organic frameworks (MOFs), including Cu-BTC, MIL-101(Cr), and ZIF-8, were also investigated. The cooling/heating performance of COF-5/ethanol and MOF/ethanol working pairs was evaluated by mathematical modelling based on the basic thermodynamic cycle of AHPs. The results demonstrated that COF-5 with the high coefficient of performance for cooling/heating (COP C /COP H ) under wide temperature lift (ΔT lift ) outperformed MOFs, especially for cooling.