Analyse thermodynamique et impact des masses thermiques sur les cycles à adsorption en utilisant les couples Maxsorb III/R245fa et SAC-2/R245fa

Adsorption cycles have been gaining significant interest in waste-heat recovery and renewable energy utilization. Adsorption isotherm data and the equilibrium cycle analysis are crucial steps in evaluating a typical adsorbent + adsorbate pair. In this paper, the performance of Maxsorb III + R245fa and spherical activated carbon, SAC-2 + R245fa were studied for adsorption cooling and adsorption heat transformer (AHT) cycles. Adsorption isotherms of these pairs were measured using the constant-volume-variable-pressure apparatus for temperatures ranging from 30 °C to 60 °C, and fitted with the Dubinin–Astakhov (D–A) and the Tóth isotherm model. An improved equilibrium model was developed, accounting the effects of thermal masses. The specific cooling energy (SCE) and the coefficient of performance (COP) of the adsorption cooling cycle were evaluated for various thermal mass to adsorbent mass ratios. It is observed that SAC-2 + R245fa pair offers better SCEs (20 kJ kg⁻¹and 160 kJ kg⁻¹ at 60 °C and 90 °C, respectively) when compared to that of Maxsorb III + R245fa. The impact of thermal mass is found to be significant for all regeneration temperatures for Maxsorb III + R245fa while the deterioration of COP in SAC-2 + R245fa is notable for high regeneration temperatures (> 75 °C). When employed in the AHT cycle, Maxsorb III offers a slightly higher useful heat while SAC-2 provides a better Q_uh/Q_QR albeit by a small margin. The Q_uh/Q_QR values for both studied pairs are more than 0.6 for all regeneration temperatures for the heat extraction at 120 °C.