On this day (07/07/2008) no cooling energy was needed in the rooms because the ambient air temperature was approximately 20 °C. Hence, the ice-storage could be charged. At the beginning of the day the storage was partially charged with approximately 15 kWh of cooling capacity. At the end of the day the storage was completely iced and a cooling capacity of 35 kWh had been available. This cooling energy had been used in the morning hours of the next days. Figure 6 shows the power supplied to the generator and the evaporator, and the solar radiation on this day.

The solar radiation on this day was very changeable. This is the reason why the operation of the chiller did not start before 11:30. It is remarkable that in spite of the inconstant solar radiation the power of the evaporator is very constant. The average COP on this day was 0.50. Figure 7 shows the operating temperatures of the chiller.

5. Conclusions

The developed absorption chiller is able to cool the rooms where the cooling system is installed, and has still some buffer capacities for higher cooling loads. In the mornings (until 9:45) and in the evenings (after 16:30) cooling performance is lacking and has to be covered with the ice storage. The ice storage could be charged on days when no cooling was required. Even on days with changeable solar radiation the charging of the ice-storage is possible. Despite the promising results so far, additional work is required. For example, the automatic control of the system must be upgraded and more measurement data have to be acquired to optimize the complete system.

References

[1] Zetzsche, Koller, Brendel, Muller-Steinhagen: Solar cooling with an ammonia/water absorption chiller, 2nd International Conference Solar Air-Conditioning, Oct. 18th/19 th 2007, Ostbayerisches Technologie-Transfer-Institut e. V., Regensburg, Germany, p. 536-541 [14]