Impact of temperature-pressure decoupling method on the performance of the dual-adsorbent bed continuous-cycle refrigeration system under desorption temperature mismatch conditions

Adsorption refrigeration technology demonstrates a significant potential for utilizing low-grade thermal energy. However, its performance is critically constrained by the specific characteristics of the heat source. This study addresses critical challenges in dual-adsorbent bed continuous refrigeration cycle systems, notably performance degradation caused by desorption temperature mismatch, poor synchronization between adsorbers, and low system efficiency, of which originate from disparate heat source temperatures. An innovative temperature-pressure decoupling (TPD) strategy was proposed, wherein a miniature vacuum diaphragm pump (MVDP) was employed to actively lower the system pressure, thereby mitigating the insufficient thermal driving force for desorption in low-temperature adsorber. A model of this decoupling method was established on the basis of the Dubinin-Astakhov(D-A) equation, providing theoretical validation for the feasibility of using pressure compensation to increase the desorption capatity of low-temperature adsorber. A desorption mismatch degree (DMD) was defined to quantitatively assess differences in desorption capatity between the dual-adsorbent bed. Experiments employing an activated carbon-methanol working pair were conducted, with electric heating simulating different heat source temperatures (adsorber 1: 110 °C; adsorber 2: 80 °C). This investigation focused on implementing pressure regulation specifically on the adsorber 2. The results demonstrated that compared with the basic adsorption cycle, the active pressure-reduction cycle maximized the desorption capatity from adsorber 2, resulting in a 45% increase. Consequently, the DMD was decreased from 48.84% to 6.98%. Ultimately, compared with those under the basic adsorption cycle, the overall system desorption capatity and coefficient of performance (COP) under the active pressure-reduction cycle increased by 21.61% and 20.95%, respectively, effectively validating the efficacy of the proposed temperature-pressure decoupling method.