Pressure- and temperature-initiated adsorption of water vapour in a finned flat-tube adsorber

Adsorption heat transformation is an environmentally friendly and effective method of using low-temperature heat from renewable, industrial and domestic sources. The transformation can be initiated by changing either adsorptive pressure (pressure-initiated, PI) or adsorbent temperature (temperature-initiated, TI). This work aims to elucidate how the initiation pathway affects the dynamics of water adsorption for silicoaluminophosphate AQSOA-FAM-Z02 loaded inside a commercial finned flat-tube heat exchanger. The main findings of this study are as follows: (a) all kinetic curves can be represented as a superposition of fast and slow exponentials associated with the process rate limitation by vapour transfer or heat transfer, respectively; (b) at a short time (<150-200 s), the PI adsorption is faster than the TI one by a factor of 3; (c) at a long time (>100-150 s), the PI desorption is slower than the TI one. From the practical point of view, the revealed differences between the PI and TI dynamics could allow the specific power of adsorption heat transformers to be improved through a better organization of the working cycle.