We decided to present the 2nd of June 2008; it was a very sunny day. We can see the evolutions of temperatures and powers on fig. 2 and 3.

At 8 AM, the outlet temperature of the solar collectors increases gradually to exceed the temperature of the hot water tank around 9 AM. At the same moment the three ways valve on the solar loop between solar collectors and the hot tank opens to warm the water of the tank. At 10 AM, the students come in the first classroom, the air temperature inside the classroom increases slightly to reach its maximum, 24°C at about 11:30 AM.

Around 11 AM, the hot tank temperature reaches 80°C, in the same time the absorption chillers starts.

At the beginning, the powers of the generator and the cooling tower are very high as we can see on the fig. 3. These powers dwindle quickly during the first hour and even more during all the functioning time. We can notice that the chiller begins to produce cold water about 10 minutes after the starting up and this refrigerated power increases slowly the next 10 minutes. Around 30 minutes later of functioning the refrigerated power stabilizes in 23 kW. At the same time the thermal COP follows closely this evolution particularly at the beginning.

We notice that the electric COP remains around 3.8 throughout the functioning of the chiller.

After less than one hour of functioning, the water of the cold tank is distributed in the first classroom. Between 12 PM and 1 PM, the students leave the classroom, so the air temperature inside the classroom decreases quickly as we can see on the fig. 2. At 1 PM, the students go back

to the classroom, so the air temperature remains around 22°C for an outside temperature of 28°C. The difference between the outside and the inside air temperature is 6°C so the comfort objective is reached.

Fig. 2 et 3: Evolution of the temperatures and powers in each components

At 4:15 PM, the temperature of the water inside the hot tank dwindles to 65°C so the generator pump stops. The generator of the chiller is not supplied by hot water but thanks to its inertia of the machine, the chiller goes on to produce cold water. This fact explains the peak of the electric and thermal COP at the end of the daily operation of the machine. Ten minutes after stopping the pump generator, the chiller stops. Finally, after 1 hour shutdown, the distribution of cold into the classroom stops because the cold tank temperature falls to 20°C.