Performance implications of chemical absorption for the carbon-dioxide-cofluid refrigeration cycle

Abstract In a CO 2 -cofluid refrigeration cycle, CO 2 condensation and evaporation are replaced by absorption into and out of a non-volatile liquid (“cofluid”). This paper investigates whether the refrigeration performance of such a cycle can be improved in theory by using a cofluid that exhibits chemical affinity for CO 2 . A Langmuir-like model is used to represent the thermodynamics of CO 2 absorption, and steady-state performance metrics are computed by solving a set of physically based equations. Chemically absorbing cofluids having sufficiently strong affinity for CO 2 are predicted to have higher specific cooling capacity and higher coefficient of performance (COP) than physical cofluids and also higher COP than transcritical CO 2 . The useful range of chemical absorption strength is limited by practical considerations like desirable operating pressures.