Distributed parameter model of a novel heat pump adsorber design using 3D-FEM

Thermally driven adsorption heat pumps can be an efficient and ecological heating and refrigeration technology for residential applications with a low effort of electric energy compared to vapor compression heat pumps. A key challenge in increasing the efficiency of adsorption heat pumps is to improve heat and mass transfer within the adsorber unit. This study therefore presents a novel stack design of an adsorber using activated carbon (AC) composites. The stack design enables a densely packed activated carbon adsorber unit with high mass transport through mass transport channels and high thermal conductance due to cohesively layered molded AC bodies between copper foils. A transient, three-dimensional distributed parameter model of the adsorber is developed and evaluated using methanol as the refrigerant. The model incorporates coupled partial differential equations for heat and mass transfer, a modified linear driving force approach for adsorption kinetics, and a Dubinin–Astakhov isotherm for equilibrium modeling. The simulation results are comprehensively compared with an ideal adsorption process in a Clapeyron diagram. The thermodynamic state variables are thoroughly analyzed over time and along the fluid flow direction. The findings show that both the operating loading and temperature difference depend strongly on the axial position and the cycle time. A heating Coefficient of Performance (COP) of 1.36 and a Specific Heating Power (SHP) of 762.6 W/kg are determined. These results demonstrate significant potential for practical residential applications, indicating enhanced performance and potential energy savings compared to existing adsorption systems. • Novel stack-structured adsorber for flat tube heat exchanger integration. • 3-D distributed parameter model for adsorber simulation. • Simulated vs. ideal adsorption process analyzed in Clapeyron diagram. • Temporal and spatially resolved analysis of thermodynamic state variables. • COP of 1.36 highlights efficiency of the new adsorber design.