Fig.3: Temperatures in the rooms

The room temperatures did not exceed 26 °C until 17:00. The chilled ceiling system was almost not able to transfer the cooling energy to the rooms. Hence, the system ran on very low temperatures in the afternoon at 13:00 to 15:00. At 16:00 the cooling performance of the chiller was slowly dropping. The reason lies in the decreasing performance of the solar collectors when the azimuth is increasing. In addition the sky became cloudy. Hence, the heat gains dropped and the cooling power as well (refer Fig. 4 and 5). After 17:00 no notable cooling power could be generated.

Figure 5 shows the operational conditions of the chiller. The average COP over the day was 0.61.

□ Total Radiation
900
□ Generator
□ Evaporator
800
700
600
500
400

300 200 100

09:00:00 10:00:00 11:00:00 12:00:00 13:00:00 14:00:00 15:00:00 16:00:00 17:00:00 18:00:00 19:00:00

Time [hh:mm:ss]

Fig. 4: Heat Fluxes (direct cooling)