## 4 Results and Discussion
### Effect of Hot Water Flow Rate  
The hot water temperature of collector outlet and generator inlet for two collector flow rates are displayed in Figure 6. It is noted that the generator flow rate is 10 m\({}^{3}\)/h. For the case in which the collector flow rate equals 3 m\({}^{3}\)/h, it is seen that the collector outlet temperature is quadratic owing to the change of solar irradiance, i.e., it grows to 85.6 \({}^{\circ}\)C in the midday and falls to 57.2 \({}^{\circ}\)C at the end of the operation. In addition, the generator pump is on at 10:17 a.m. when the top layer temperature of the storage tank reaches the activation temperature by solar heat. The sudden drop of generator inlet temperature is caused by the insufficient solar heat of a storage tank. Similarly, the hot water temperature of generator inlet is also quadratic since it is primarily controlled by the collector outlet temperature. It is demonstrated that the peak generator inlet temperature is 73.1 \({}^{\circ}\)C. For the case in which the collector flow rate is 10 m\({}^{3}\)/h, the collector outlet temperature comes down because of the decreased temperature difference caused by the improvement of collector flow rate. It is observed that the collector outlet temperature fall by nearly 10 \({}^{\circ}\)C as the collector flow rate goes up by 7 m\({}^{3}\)/h. In addition, the mentioned temperature drop gradually diminishes with the reduction of solar irradiance. There is not a sudden drop of generator hot water temperature as the activation of generator pump delays by 6 min compared with low collector flow rate. This phenomenon is attributed to the fact that the amount of solar heat in a storage tank is far greater than the consumption of absorption chillers. Thereby, the hot water temperature of generator inlet rises approximately by 1.7 \({}^{\circ}\)C as the collector flow rate grows from 3 m\({}^{3}\)/h to 10 m\({}^{3}\)/h. The hot water temperature of the collector outlet and generator inlet for two flow rates of generator hot water are exhibited in Figure 7. It is mentioned that the collector flow rate equals 10 m\({}^{3}\)/h. It is shown that the collector outlet temperature becomes lower for the enhanced flow rate of generator hot water due to the higher consumption of the absorption subsystem, as expected. The collector outlet temperature falls by around 7.0 \({}^{\circ}\)C when the hot water flow rate of generator increases from 3 m\({}^{3}\)/h to 10 m\({}^{3}\)/h. Simultaneously, the generator pump is on 17 min earlier as a result of the decrease of  
Figure 6: Hot water temperature for different \(\dot{V_{c}}\). activation temperature. Nevertheless, the hot water temperature of the generator inlet goes down by about 7.6 \({}^{\circ}\)C for the hot water flow rate of a generator rising by 7 m\({}^{3}\)/h. The dependence of collector and absorption subsystem performance on a collector flow rate is displayed in Figure 8. Because the heat transfer coefficient enhances with the improvement of flow rate, the daily useful heat of collector goes up by 15.6% for the collector flow rate grows from 1 m\({}^{3}\)/h to 10 m\({}^{3}\)/h. Additionally, such enhancement of solar heat becomes tiny when the collector flow rate exceeds 4 m\({}^{3}\)/h, which is similar to conclusions of the reference [21]. It is explained by the insignificant growth of heat transfer coefficient with the flow rate in the turbulent flow region. On the other hand, the increase of generator hot water temperature leads to the weak effect of collector flow rate on the performance of absorption subsystem, i.e., the daily mean COP of absorption subsystem only goes up by 2.2% when the collector flow rate rises from 1 m\({}^{3}\)/h to 10 m\({}^{3}\)/h. Accordingly, the daily cooling power of the absorption subsystem enhances by 22.5% due to the increasing solar heat and COP of the absorption chiller.