## 4 Conclusions  
Simulation results were compared with experimental results previously obtained by Millennium Industries. From the simulation results, the following conclusions were drawn:  
1. The model could predict optimum parameters for cycle time, heat recovery time, switching time, activated carbon mass and mass flow rates for bed, condenser and evaporator heat exchangers. 2. The simulation model results agreed well with experimental data in terms of cooling capacity up to 7 kW and Coefficient of Performance (COP) up to 0.4. 3. The simulation model showed a transition period of 1000 s to reach a steady state, which is equal to three complete adsorption/desorption cycles. 4. The model optimized the adsorption/desorption cycle time (300 to 400 s), switching cycle time (50 s) and heat recovery cycle time (30 s). The optimized times maximized both cooling capacity and COP up to 0.4. 5. The COP predicted by this simulation is very close to the Carnot cycle for the heat recovery mode working at the same operating conditions (95%). 6. The chiller without heat recovery mode achieved a very low COP when compared with the Carnot cycle COP and the COP for heat recovery mode at the same operating conditions. 7. The water outlet temperatures for beds, evaporator and condenser predicted by the simulation agreed, to a reasonable extent, with the experimental data. 8. Increasing the cycle time increases the degree to which the capacity of the bed is used. However, increasing the cycle time up to a certain value increases the average system power, and if the cycle time is increased further, the increase in the capacity per cycle is less than that of the increase in cycle time. In other words, as cycle time is increased further, the average power decreases. Then, there exists a certain cycle time for optimal average system power, which is between 300-400 s.
9. The heat recovery mode has a COP higher than that of the ordinary mode and has almost the same cooling capacity over a wide range of operating conditions. 10. The model predicts different sizes of the chiller for activated carbon/methanol pairs and could be used with minor modifications for other working pairs at the same conditions. 11. The two-stage chiller could be driven by using low waste energy with a low COP or a high temperature heat source with a high COP compared with the Carnot cycle COP. 12. This study could be used as a basis for series production of a two-stage air cooled adsorption chiller. 13. The model will be used for further studies including a desalination function added to the current chiller and integration with other systems such as turbines or any form of hybrid cogeneration. Conceptualization, F.M.M. and A.A.A.-M.; methodology, F.M.M. ; software, F.M.M. ; validation, F.M.M., A.A.B. and A.A.A.-M.; formal analysis, F.M.M. ; investigation, H.A. ; resources, A.A.; data curation, A.A.; writing--original draft preparation, F.M.M. ; writing--review and editing, A.A. and H.A. ; visualization, F.M.M. ; supervision, A.A.A.-M. and A.A.B. ; project administration, F.M.M. All authors have read and agreed to the published version of the manuscript. This research received no external funding. Not applicable. _Appl.