Modeling and experiments on a finned cylindrical reactor with expanded graphite/activated carbon/lithium chloride-ammonia for chemisorption refrigeration systems

Highlights: • An unsteady, 2-D axisymmetric model for a finned adsorbent bed is presented. • The model has the capability to estimate COP and SCP and other operational variables. • The model developed demonstrated good agreement with experimental data • Model includes dynamic convection boundary conditions between adsorbent and adsorbate material. • Experimental validation uses an adsorbent bed composed by a AC/GE/LiCl-25% NH3/H2O mixture v/v pair. This paper presents a transient heat and mass transfer model with experimental validation of a finned cylindrical adsorbent bed for performance analysis in chemisorption refrigeration system. The approximate solution for the mathematical model, including transient heat and mass transfer equations in cylindrical coordinates, was obtained by implementing the Crank-Nicholson approach in a finite difference scheme. Geometrical configuration and physical parameters, including bed material thermal properties and TGA-based kinetic modeling for reaction rate estimation, were used as model data inputs to predict thermal bed distribution, heat flows, and coefficient of performance for a refrigeration system. Results from the model were validated with transient data from a chemical sorption refrigeration test bench. Refrigeration system reactor was made of expanded graphite/activated carbon/lithium chloride (AC/EG/LiCl)-adsorbent (NH₃ in solution with a 25% concentration). The model demonstrated excellent agreement and an adequate representation of the physical phenomena, constituting a potential tool for efficiency-enhancing development of adsorption reactors for refrigeration systems.