On Effective Design and Operating Conditions of Desiccant Dehumidification System

Abstract

The present study investigates the effect of air flowrate on the adsorption systems both numerically and experimentally. Tests are performed with Zeolite 4A adsorbent. The size of test desiccant channel section is 10cm x 10cm x 10cm, and three test sections in series connections are used as the test section during adsorption and desorption. During adsorption, the inlet pressure is kept at 9bar while it is reduced to 1.16bar during desorption. The simulation is first validated with the experimental data. The simulation indicates though a higher airflow during adsorption can produce dry air quickly but may not be able to attain a prescribed very low dew point temperature. Yet lower airflow can dehumidify more moisture and attain much lower dew point but requires substantial time. For the required energy to generate the same dry air flow volume in cyclic operation, it was obvious that a lower flowrate like 150 standard liter per minutes (SLPM) is about 4% lower than that of a higher flowrate of 400 SLPM. For effective regeneration during desorption, a non-uniform heating provided at the first section is proved to be much effective than the uniform heating. It is found that the desiccant loading for only heating at the first section outperforms other arrangements, giving 10% lower desiccant loading than the uniform heating.