Indoor thermal environment and air distribution in a floor-ceiling heating room with mixing or displacement ventilation

Abstract

A hybrid system with a floor-ceiling heating system (FCH) and a mixing or displacement ventilation system (MV or DV) is a potential advanced heating, ventilation, and air conditioning system in the modern buildings. To date, very few studies focused on the indoor thermal environment and air distribution for FCH + MV or FCH + DV. Therefore, in this article, the effect of double heated surface temperature on indoor thermal environment and air distribution in a simulated office room with FCH + MV or FCH + DV were studied. Vertical distributions of air temperature and velocity and globe temperature in the occupied zone and horizontal distributions of contaminant concentration in the breathing zone were measured when floor and ceiling surface temperatures ranged from 25.0 °C to 29.5 °C. Vertical air temperature difference, turbulence intensity, difference between operative temperature and air temperature, and air distribution effectiveness were calculated and compared for all test conditions. The results showed that the vertical air temperature differences were all less than 0.5 °C with both positions for FCH + MV and were 4.0 °C to 4.9 °C with sitting position and 4.3 °C to 5.3 °C with standing position for FCH + DV. The turbulence intensities were from 12.5% to 17.5% with sitting position and from 12.8% to 17.1% with standing position for FCH + MV and were all within the range of 10% for FCH + DV. The differences between operative temperature and air temperature were all no more than 0.5 °C with both positions for FCH + MV and FCH + DV. The air distribution effectiveness was close to 1.0 with FCH + MV and between 1.04 and 1.21 with FCH + DV. The results in this article are relevant to the design and operation of an FCH integrated with an MV or DV.