Analysis of energy and humidity performance of a system combining chilled ceiling with desiccant cooling

An HVAC system combining chilled ceiling with desiccant cooling (CC+DC) is proposed for hot and humid climates where air dehumidification is required to maintain the indoor air humidity within a comfort zone and to reduce the risk of water condensation on chilled panels. Through hour-by-hour simulations, the annual energy consumption of the system is calculated and compared with two other systems: conventional constant volume all-air (CAV) and chilled ceiling with air-handling units (AHU) dehumidification (CC+AHU). The results indicate that a chilled-ceiling system combined with desiccant cooling could save up to 30%o of primary energy consumption and would result in 40% more annual hours in the comfort zone of relative humidity, compared to a conventional constant volume all-air system. The results also indicate that starting the dehumidification and ventilation system prior to the operation of ceiling panels is required to reduce condensation risks in hot and humid climates. However, beginning dehumidification one hour earlier than ceiling panel operation in summer could completely eliminate the condensation problems in humid climates. More interestingly, more than 70% of annual operating hours for the desiccant system could be accomplished using low-grade heat of less them 80°C (176°F).