Thermal design and management is important to improve the CO2 capture by adsorption's efficiency, but current studies only consider geometric designs of a specific size. This paper develops a 2D multi-physics model to study how the spacing between two fluid pipes in the adsorbent bed affects the desorption performance, which couples the species transport, fluid dynamics, and heat transfer modules. Specifically, the model involves sandwiching the adsorbent bed between two fluid pipes, which will be parametrically studied in terms of the CO2 desorption performance, with indicators being the thermal efficiency, and the speed of CO2 desorption. Results reveal that a trade-off exists where the desorption speed decreased from 0.9 to 0.05 mol/(m3 s) when the bed height changes from 1 cm to 10 cm, but the thermal efficiency will correspondingly increase from 0.52 to 0.85. Furthermore, a sensitivity analysis on this trade-off situation is conducted by varying the thermal conductivity, regeneration temperature, CO2 feed concentration, and applying thermally conductive fins. Results reveal that increasing the thermal conductivity provides the most reasonable performance improvement characteristics as it halved the desorption time while the specific energy consumption for CO2 capture remains largely unaffected.