Impact of adsorbent finishing and absorbent filming on energy exchange efficiency of an air-to-air cellulose fibre heat & mass exchanger

This paper aimed to investigate the impact of two coating methods, namely solid adsorbent (CaCl2) finishing and liquid absorbent (LiCl) filming, on energy (enthalpy) exchange efficiency of a cellulose fibre air-to-air heat & mass exchanger, through both theoretical analyses and experimental testing. Heat and mass transfer through three types of membrane, i.e., clear fibre and the fibre with adsorbent finishing and absorbent filming, were analysed. This led to the conclusion that the coating on the membrane would help improve energy exchange efficiency of the exchanger. Experimental testing was carried out for the exchangers with the two coatings, and the testing results were compared with the existing data of a clear fibre exchanger. It was found that absorbent (LiCl) filming had larger impact towards the energy exchange than the solid CaCl2 powder did, and the level of efficiency increase for the two coatings are 25.6% and 15.9%, respectively. However, the inherent problems existing in liquid absorbent system, i.e., complexity of the desiccant cycle and potential air contamination by desiccant solution, limited its wide application in practical engineering, and therefore, the adsorbent finishing is a suitable option for this purpose.