## 3 Results and Discussion
### The Bed Average Pressure, Temperature and Uptake  
Figure 8 illustrates the cyclic change of the averaging of the bed's main parameters, which are the pressure, the temperature, and the uptake, at different cycle times and composite thicknesses. In general, the effective uptake during a complete cycle increases with increasing the cycle time, while it decreases with increasing the composite thickness. The hysteresis of the adsorbate in the beds during repeated adsorption and desorption processes was reduced with a longer cycle time. This can be indicated by the increase in the enclosed area of each cycle at higher cycle time, as shown in Figure 8a-c at different composite thicknesses. The additives and binder represent 50% of the carbon-based composite in the present study which reduced the total porosity to 0.3483 even though the highly porous carbon type Maxsorb III was used. This low porosity has a considerable impact on the interparticle mass transfer, particularly when the composite thickness is increased. Therefore, increasing the composite thickness from 2 to 10 mm decreases noticeably the effective uptake. In case of 10 mm composite thickness shown in Figure 8c the positive effect of the longer cycle time was more pronounced during the desorption process as it decreased the lower uptake limit. However, the upper limit of the uptake during the adsorption process was slightly increased with increasing the cycle time. This was affected by applying the very lower pressure level in the beds during the adsorption process to keep the evaporator under \(-2\)\({}^{\circ}\)C combined with the higher composite thickness used. Figure 8: _Cont._The Performance of the Ice Production System  
The net impacts of the changing of the cycle times on the SDIP and COP of the ice production system at composite thicknesses of 2, 5, and 10 mm are shown in Figure 9. Overall, increasing the cycle time, in the given range, can either increase or decrease the SDIP of the system depending on the composite thickness. However, the COP of the system has increased by increasing the cycle time regardless of the composite thickness. A maximum SDIP of 33.27 kg\({}_{\text{ice}}\)-kg\({}_{\text{ads}}\)\({}^{-1}\)-day\({}^{-1}\) was attained at the shortest cycle time of 430 s and the smallest composite thickness of 2 mm. Nevertheless, the system COP reached its maximum value of 0.3046 at the longer cycle time of 1230 with 5 mm composite thickness, and the SDIP associated with this case was 23.27 kg\({}_{\text{ice}}\)-kg\({}_{\text{ads}}\)\({}^{-1}\)-day\({}^{-1}\). The changing range of the SDIP over different cycle times was considerably reduced by increasing the composite thickness as it can be seen by comparing the range of the SDIP given in Figure 9a-c. This was attributed to the reduction in the effective uptake with thicker composite thickness. Figure 8: P-T-Xeq diagram for the carbon-based composite adsorbent bed in a complete cycle under different cycle times and composite thicknesses of (**a**) 2 mm, (**b**) 5 mm, and (**c**) 10 mm. Figure 9: _Cont._  
In the case of 2 mm composite thickness, the SDIP decreased gradually from its maximum value of 33.27 kg\({}_{\text{ice}}\cdot\)kg\({}_{\text{ads}}^{-1}\cdot\)day\({}^{-1}\) at 430 s to 27.66 kg\({}_{\text{ice}}\cdot\)kg\({}_{\text{ads}}^{-1}\cdot\)day\({}^{-1}\) at 1230 s. This reduction was affected by the slower adsorption and desorption rates at a higher cycle time as the instantaneous uptake approached the equilibrium uptake in a short time. However, this was not the case with 5 mm composite thickness, as depicted in Figure 9b, as the kinetics remained at a higher level for a longer time compared with the case of 2 mm composite thickness. Therefore, the maximum SDIP of 24.1 kg\({}_{\text{ice}}\cdot\)kg\({}_{\text{ads}}^{-1}\cdot\)day\({}^{-1}\) with 5 mm composite thickness was attained at 830 s. The slower adsorption and desorption rates at a higher cycle time of more than 830 s hampered the increase in the SDIP that started to be reduced.