Prediction of the effective thermal conductivity of an adsorption bed packed with 5A zeolite particles under working conditions

To predict effective thermal conductivity (ETC) of an adsorption bed during the adsorption process, a scale-up model is established that couples a macro-level comprehensive thermal conductivity model and a microlevel grand canonical Monte Carlo (GCMC) method. The effect of the adsorbed phase on the gas phase thermal conductivity is comprehensively considered. The proposed model is validated with experimental data for the thermal conductivities of the zeolite adsorbent particles and bed. Comprehensive sensitivity analyses regarding the effects of the pressure and temperature on the ETC of the adsorption bed are conducted. The results show that the thermal conductivities of the zeolite adsorbent particles and bed can be divided into three regions, namely, the weak adsorbed phase region (0–0.1 kPa), the adsorbed phase and gas phase competitive region (0.1–50 kPa), and the saturation adsorption region (50–1000 kPa). Inflection point temperatures of 350, 450, and 600 K are identified for the three regions. The gas adsorption effect can be ignored when the temperature is higher than these inflection point temperatures. The ETC of the adsorption bed will be underestimated when the adsorption phase is not considered, and it will be overestimated when the coupled effect of the adsorption phase and gas phase is ignored.