Desiccant Dehumidification Integrated with Hydronic Radiant Cooling System

Abstract

The performance of desiccant dehumidification assisted by a hydronic radiant cooling system for humid climates is evaluated by determining the minimum relative humidity, saturation state of the desiccant dehumidifier, dehumidification capacity, controlling relative humidity, power consumption, response of chilled ceiling for thermal comfort, and room dew-point temperature. Thermal comfort condition was evaluated by determining preferred room temperature experimentally and optimum ventilation configuration numerically. The objectives of the study are to determine the ability of the desiccant system to reduce the moisture and the capacity of the chilled ceiling panels to provide the thermal comfort condition. The results show that the relative humidity is reduced to 40 % with a dry bulb temperature of 35 °C, allowing for a high dehumidification capacity of 2.673 kg/h to be achieved within 10 min with an airflow rate of 243 kg/h. A chilled ceiling surface temperature between 14 and 18° C was achieved by varying the chilled water inlet temperature from 6 to 10 °C at steady state. Condensation was absent on the chilled ceiling surface panels below 70 % of relative humidity. The thermal comfort room temperature for this investigation was set to 24 °C, based on occupant’s satisfactory sensation and on Design-Expert software optimization, which is consistent with standard thermal comfort. However, for economic reason, the chilled ceiling position of 2 m is preferable and 3 m is within optimum ventilation configuration. Performance of ventilation configuration is a function of numerous factors, of which the most important are fresh air distribution observation, stagnation zones, air circulation, path line size, air age inside the environmental chamber, air velocity, and ventilation effectiveness. Nine displacement ventilation configurations with respect to chilled ceiling positions within environmental chamber were investigated, to determine the optimum thermal comfort condition. An inlet and outlet diagonal location with respect to chilled ceiling position of 3 m was found to be the optimum configuration. This study proposed solutions for improving thermal comfort in hot humid climates using chilled ceiling system integrated with desiccant dehumidification system.