A novel operating strategy to avoid dew condensation for displacement ventilation and chilled ceiling system

Abstract

Avoiding dew condensation on chilled ceiling is crucial for the application of displacement ventilation and chilled ceiling systems. Comparison with the conventional operating strategy, a novel operating strategy is proposed to control the humidity ratio of air near ceiling. When operating, chilled ceiling is closed at the initial stage and will be opened by verifying that the dew point temperature of the air near ceiling is 2 K lower than the operating temperature of ceiling surface. Different options to shorten the time of initial stage were investigated by simulation including raising the flow rate of the supply air and decreasing the humidity ratio of ventilation. Results show that the phenomenon of dew condensation on the displacement ventilation and chilled ceiling system can be alleviated with this strategy. With the optimization of supply air parameters the time of preparation process can be shortened to 180 s. This study provides a novel insight of optimization for displacement ventilation and chilled ceiling systems, which may become an important approach for preventing chilled ceiling from condensation.