Research On Airflow Patterns And Control Strategies Of The Hybrid System With Radiant Cooling And Dedicated Outdoor Air

The Hybrid System with Radiant Cooling and Dedicated Outdoor Air not only possesses great potential of improving energy efficiency, but also creates a more healthy and comfortable indoor environment than traditional air-conditioning systems. With indoor thermal comfort enhanced by the Radiant Cooling System (RCS) and indoor air quality improved by the Dedicated Outdoor Air System (DOAS), the new hybrid system complies with the tendency to construct energy efficient buildings. In order to develop the advantages and provide valuable references for popularization of the hybrid system, this article analyzed the characteristics of the new system from the perspectives of airflow patterns and control strategies.The research was initiated by theoretical analysis. Calculation models to reflect the effect of each component and numerical models to select the proper airflow pattern were established for the following study. Artificial neural network optimized by genetic algorithm was set as the feedback loop of the control model from the view of bionics.The differences of radiant cooling terminals and handling methods of fresh air exert influences on the cooling capacity and dehumidifying capacity of the hybrid system respectively. The system type was determined by comparing of three energy consumption models based on enthalpy analysis and the design conceptions were concluded during the process of building a full-scale experiment chamber. Such chamber offered an experimental platform to the testing of cooling capacity of the system and multi-index appraisal of different airflow patterns operated along with the ceiling radiant cooling panels (CRCPs). After verifying the consistency between calculated and measured cooling capacities of CRCP and that of measured cooling load and calculated cooling capacity of the hybrid system respectively, the optimal proportion for cooling capacities of CRCP accounts for the total cooling loads was found.The control sequence of relevant parameters can be determined by the orthogonal experiments applying with the numerical simulation. The overhead supply airflow pattern was recommended as the best combination way for hybrid system after comprehensive comparison of the numerical simulation and experimental results, while control strategies for the hybrid system were also established.Preliminary investigations were conducted on the moist stratification and the control effect of different airflow patterns to prevent condensation on CRCP. Stratified nodes were found on the height of 0.6m and the position beneath the panel and the overhead supply airflow pattern was reconfirmed as the best combination way for the hybrid system from the point of view of condensation control. Finally, control strategies aiming at preventing condensation on CRCP were also put forward.