Study on heat transfer delay of exposed capillary ceiling radiant panels (E-CCRP) system based on CFD method

摘要

The exposed capillary ceiling radiant panels(E-CCRP) system is a newly developed terminal device that has been gradually applied in public buildings in recent years. The heat transfer between the system and indoor environment is the combined heat transfer of thermal radiation and natural convection. Currently, most researchers discuss the radiation heat transfer under steady-state conditions, but the actual process is dynamic. Real-time control is needed in the actual operation of the system, and the heat transfer delay of radiation system must be considered in the implementation of effective control. In this paper, a CFD model of an office with E-CCRP system was used to analyze radiant heat transfer characterize and time delay during the E-CCRP start-up process in winter under unsteady-state conditions. Experiments were conducted to verify the accuracy of simulation results. Based on the model, the influencing parameters of time delay were further studied. The study showed that, the system took about 5 h to get nearly steady status after the start-up because of the thermal inertia, and the time delay of system and indoor heat transfer was about 1 h. The model was proven to be correct since the maximum relative errors between experimental data and simulation results were within 7%. The supply water temperature has a greater impact on the time delay than the indoor initial temperature. The model can be extended to other radiation terminal systems, and time delay obtained can make the dynamic control of system more reasonable and energy-saving.