Using revised ADPIs to identify an optimum positioning for installation of reversible room air-conditioners in bedroom for maximum thermal comfort

摘要

It has been a common practice to place room air-conditioners (RACs) at overhead level for cooling of residential environments because this offers better air distribution performance and thus thermal comfort. However, now reversible RACs are gaining ground and they comprise both cooling and heating modes. Whether the same practice of locating RACs at overhead level should continue for reversible RACs has never been investigated. This study is the first ever attempt to identify the optimum positioning (position and level) for installation of reversible RACs in a representative bedroom. Computational Fluid Dynamics (CFD) and EnergyPlus simulations were integrated for the purpose and experiments were conducted in an environmental chamber to provide data for validation of the CFD settings. EnergyPlus simulations were used to determine the hour-by-hour cooling and heating demands based upon realistic operating and probable equipment characteristics. The probable equipment characteristics were ascertained by an extensive market survey and Monte Carlo analysis. The hour-by-hour cooling and heating demands were analysed by Central Composite Design method and the Squeeze Theorem for the formulation of the representative cooling and heating data sets for further CFD simulations. Further CFD simulations provide an accurate prediction of air temperatures and velocities for different installation positioning for thermal comfort analysis. Revised air diffusion performance indices (ADPIs) were developed to facilitate thermal comfort analyses for cooling and heating modes. It was found that slightly higher ADPIs can be obtained when the reversible RAC is installed at high level and on the longer side of the bedroom.