Impacts of convection on the thermal performance of radiant heating system with novel dry radiant module

The transient response of the radiant floor heating system (RFHS) and the influence of convection on the radiant heating are rarely reported. In this work, Experiments were carried out for independent RFHS (case A) and combined RFHS with convection (case B). The dry radiant module (DRM) was applied to the radiant floor, and the assisted ventilation was used selectively to investigate its influence on the thermal performance. Compared with the independent RFHS, the convection is effective to reduce the startup time by 20 min, and to accelerate the decrease in air temperature after shutdown. The floor surface temperature has a dropping-rising-dropping trend when the system is shutdown no matter the fan coil works or not. But the rising range of case B is smaller than case A. It shows that the combined system can reduce the influence of the thermal inertia of the radiant floor, improve the reaction of indoor air, and meet the requirement of rapid heating better. For case B, the horizontal temperature fluctuation is smaller at 0.1 m height and larger at 1.7 m height than case A. The simulation results indicate that the forced airstream breaks the air circulation caused by natural convection, and causes a significant vertical temperature fluctuation. The results provide a guide for better design and operation of RFHS.