## 7 Conclusions  
Solar absorption cooling system designed for a peak cooling demand of 108 kW was modeled and simulated by using TRNSYS. The components in the TRNSYS standard library are employed and linked in all possible flow schemes between the storage-chiller loop with different control strategies of the working fluid. An educational building located at Peshawar (34\({}^{\circ}\) N, 71.54\({}^{\circ}\) E), where a vapor compression cooling system of 108 kW cooling capacity was replaced by SACS, was selected to simulate the system for the whole summertime. The best collector slope was found to be around 9\({}^{\circ}\) for ETC and 15\({}^{\circ}\) for FPC at the highest solar fraction. Results also indicated a perceptible difference between maximum monthly averaged efficiencies for both collector types as shown in Figure 13. Hence, it can  
Figure 19: Validation of optimum storage size. (**a**) Variation of Auxiliary energy consumption with tank volume for climate of Pakistan. (**b**) Variation of Auxiliary energy consumption with tank volume for climate of Algeria.  
Figure 17: Validation of monthly solar fractions. (**a**) Seasonal solar fraction trend for city of Pakistan. (**b**) Yearly solar fraction trend for city of Malaysia.  
Figure 18: Validation of optimum slope. (**a**) Useful Collector Gain Vs Collector Slope for city of Pakistan. (**b**) Useful Collector Gain Vs Collector slope for city of Malaysia.  
be decided that the flat plate collector is not an ideal option for the presented study because of the requirement of more than five times larger area than ETC. Primary energy saving is much better for Scheme 3 compared to Schemes 1 and 2 with matching storage at somewhat smaller collector areas for ETC. The discrepancy in the fraction of primary energy saving of all schemes shrinkages for higher collector area as shown in Figures 9 and 10, but for real scenarios, economics consideration of the system is also involved while deciding to use higher collector areas. Monthly SF curves for ETC, as shown in Figure 15, in current simulation results also indicated S-3 is far better than the other two schemes to be exploited. In Figure 16, collector area per kW of refrigeration is plotted. Scheme 3 has the smallest area/kW for both ETC and FPC for achieving 50% energy savings. Overall, flow scheme-3 with evacuated tube collector is considered as the best selection for the current study to use with the smallest ratio of collector area to kW of cooling capacity. Because of insufficient experimental records that can be used for direct validation of current results, trends in previous publications of simulation studies were found to be matched with current simulation trends.  
Conceptualization by [PERSON], [PERSON] and [PERSON]. Methodology, modeling and the discussing of the whole system by [PERSON], [PERSON] and [PERSON]. Writing- original draft preparation and editing by [PERSON], [PERSON] and [PERSON]. [PERSON]. Writing- review and editing by [PERSON], [PERSON] and [PERSON]. Investigation and general discussion by [PERSON], [PERSON] and [PERSON]. Overall English and grammar editing by [PERSON] and [PERSON] and [PERSON]. Overall Supervision by [PERSON] and [PERSON]. Funding Acquisition by [PERSON] All authors have read and agreed to the published version of the manuscript. This research was funded by the Guangdong Basic and Applied Basic Research Foundation grant number (2019A1515111189) and Natural Science Foundation of SZU grant number (2110270). The authors declare no conflict of interest. The following abbreviations are used in this manuscript:  
VCCS vapor compression cooling system  
HTF heat transfer fluid  
ETC evacuated tube collector  
FPC flat plate collector  
IAM incident angle modifier  
S-1 Scheme-1  
S-2 Scheme-2  
S-3 Scheme-3  
SACS solar absorption cooling system  
PES Primary energy saving  
SF Solar fraction  
COefficient of performance