Dynamic simulation regarding the condensation risk on a cooling ceiling installed in an office room (original) (raw)

Some aspects of controlling radiant and convective cooling systems

E3S Web of Conferences

Designing appropriate control systems for radiant heating and cooling terminals entails an understanding of their dynamic behaviour. This study experimentally investigates the dynamic response of a room with convective and radiant cooling systems. The experiments were performed in a 12.6 m2 large test room outfitted as a single-office room. The main cooling system was radiant ceiling panels which covered 70% of the ceiling area. The thermal performance of the radiant system was compared to that of a fan-coil unit (FCU). The results from the step response test showed that the time constant of the room for the radiant system was shorter than for the convective one, indicating faster changes in room temperature by the radiant system. Furthermore, controlling the FCU with similar control system tuned for ceiling panels increased the hysteresis gap in the room air temperature from 0.4 K to 0.8 K. This indicates that control systems for low-mass radiant systems and convective systems migh...

The Impact of Thermal Radiation on Condensation on Cold Surfaces of Ventilated Rooms

2016

The objective of this study is to investigate the impact of radiative heat transfer on the global exchange of thermal energy between indoor surfaces and air in rooms. In addition, this paper is focusing on the influence of this phenomenon on water vapor condensation on cold surfaces. The approach is based on CFD (Computational Fluid Dynamics) technique, using an integrated moisture–heat–air flow methodology, required for comprehensive thermal investigations and condensation mechanisms. Basically, transport equations for radiation intensity to solve the radiative heat transfer and equations expressing the conservation of the water vapor mass fraction are added to the equations governing a turbulent confined nonisothermal airflow. The numerical model is applied in the case of a room with mixing ventilation and radiant floor heating system. One of the vertical walls of the enclosure is assumed to be cold to favor the condensation on its surface. For the purpose of this study, this conf...