Effect of residual air on dynamics of temperature- and pressure-initiated adsorption cycles for heat transformation

It is well known that non-adsorbable gas, e.g. residual air, can dramatically slow down the adsorption stage of adsorption heat transformation cycles. So far, this effect has been studied for the cycles initiated by temperature change (temperature-initiated cycles). This work addresses the dynamic effect of residual air for another way of adsorption initiation, namely, by changing vapour pressure over adsorbent (pressure-initiated cycle). Comparison of the pressure- and temperature-initiated cycles is also made. The effects are studied for the working pairs AQSOA FAM-Z02 - water and LiCl/(silica gel) - methanol promising for adsorption heat transformation. The residual partial air pressure Delta Pair was varied from 0 to 5 mbar. The main finding of this study is that the pressure-initiated adsorption is less sensitive to the presence of residual air than the temperature-initiated adsorption. This is especially true at a low partial air pressure Delta Pair. For instance, at Delta Pair <= 0.5 mbar, residual air has little or no effect on the pressure-initiated adsorption dynamics compared to the temperature-initiated one. A qualitative explanation of this finding is proposed. Thereby, closed adsorption heat transformation cycles based on the pressure-initiated process are more robust and resistant against the presence of residual air that could be a significant practical advantage.

Automated summary

This study examines the dynamic effect of residual air on pressure-initiated and temperature-initiated adsorption heat transformation cycles, finding that the pressure-initiated adsorption is less sensitive to the presence of residual air, especially at low partial air pressure. This suggests that closed adsorption heat transformation cycles based on the pressure-initiated process are more robust and resistant against residual air, potentially offering a significant practical advantage.