Condensation risk of DCDV system for hot and humid Hong Kong

The combined use of dry cooling air-handler and dedicated ventilation (DV) system for energy saving and better indoor condition has been confirmed effective. But the application of this system is hindered by the condensation risk on dry cooling coil. In this study, the condensation risk of the use of dry cooling air-handler and dedicated ventilation (DCDV) system in subtropical climates was examined by analysing its application in a typical office building in Hong Kong using actual equipment performance data and realistic system characteristics. Through hour-by-hour simulations it was found that the annualised cumulative frequency of occurrence of condensation (ConHR) for normal operation of the office building was acceptable. However, departures of the in-use condition from design values are inevitable. Additional parametric studies were therefore performed to evaluate the influence of five design parameters on the ConHR, and to identify the influential factors. By statistical analysis, it was found that ConHR was most sensitive to changes in system latent load, followed by (descending order) system sensible heat ratio, system total load and design moisture absorption coefficient of dry cooling coil. Furthermore, a regression model relating ConHR to latent load, sensible heat ratio, total load and design moisture absorption coefficient was established for minimising condensation risk during the design of DCDV system.