Performance Comparison of Enthalpy Recovery Devices Using Liquid Desiccant and Desiccant Wheel

Abstract

Heat recovery between outdoor air and indoor exhaust air is an effective approach for energy-saving in the air-conditioning system. Performances of enthalpy recovery devices using liquid desiccant (LD) and desiccant wheel (DW) are compared in the present study. Effects of key factors including desiccant flow rate, number of transfer units (NTUm), and air inlet parameters on recovery performance are analyzed. There exists the same ideal recovery efficiency with a given NTUm for these two kinds of devices. However, an optimal solution flow rate could be achieved for enthalpy recovery device using LD, while a higher rotation speed leads to a higher recovery efficiency for that using DW. Recovery efficiencies of the two devices increase with the increase in NTUm, while they have different ranges of NTUm. NTUm of the DW is usually superior to that of the LD, due to the material difference. Then, the optimum methods to improve recovery efficiency of the two devices are clarified, i.e., increasing NTUm for an enthalpy recovery device using LD and choosing a reasonable rotation speed for that using DW, respectively. The present research will be beneficial to cast light on the relation between enthalpy recovery devices using LD and DW.