## 5 Results
### Sizing Analysis  
Figure 8 shows the effect of the pressure ratio on the \(UA\) of high and low-temperature recuperators. Solar salts present a higher \(UA\) value for both recuperators. For the MgCl\({}_{2}\)-KCl salts, the minimum \(UA\) for the high-temperature recuperator (HTR) is 400.1 kW/K at a pressure ratio of 3.025. The minimum \(UA\) for solar salts is 499.1 kW/K at a pressure ratio of 3. For the low-temperature recuperator (LTR), the minimum \(UA\) for chloride salts is 404 kW/K at a pressure ratio of 3.075, while for solar salts, it reaches a minimum of 650.7 kW/K at a pressure ratio of 3.1. The results indicate that the system operating with MgCl\({}_{2}\)-KCl salts reduces \(UA\) for both the HTR and LTR by 19.83% and 37.81%, respectively.  
Figure 9 shows the \(UA\) for the intermediate heat exchanger (IHE) and the precooler (PC) at different pressure ratios. Chloride salts show a lower \(UA\) for the intermediate heat exchanger and precooler at all pressure ratios. For MgCl\({}_{2}\)-KCl salts, the minimum \(UA\) for the IHE is 1089 kW/K at a pressure ratio of 3.05, while for solar molten salts, this minimum is 1233 kW/K at a pressure ratio of 3. The minimum \(UA\) for the precooler is 353.4 kW/K for the chloride salts compared to 529.5 kW/K for solar salts. As a result, the MgCl\({}_{2}\)-KCl salts decrease the \(UA\) for the IHE and precooler by 11.68% and 33.26%, respectively.  
Figure 10 illustrates the \(SP\) on the turbine, main and recompression compressors at different pressure ratios. For both the turbine and the main compressor (Figure 10a,b), the \(SP\) reaches a minimum at an intermediate pressure ratio. For solar salts, the minimum \(SP\) for the turbine is 0.3609, occurring at a pressure ratio of 2.85, while for the main compressor, it is 0.1531 at the same pressure ratio. In the case of MgCl\({}_{2}\)-KCl salts, the minimum \(SP\) for the turbine is 0.3189 at a pressure ratio of 2.975, and for the main com  
Figure 7: Comparison of exergy destruction in turbines and compressors at different pressure ratios.  
pressor, it is 0.129 at a pressure ratio of 2.875. In the case of the recompression compressor (Figure 10c), the \(SP\) exhibits a maximum at an intermediate pressure ratio. The minimum \(SP\) is achieved at the lowest pressure ratio for the solar salts and at the highest pressure ratio for the chloride salts. The minimum \(SP\) for the recompression compressor is 0.1625 for solar salts and 0.1298 for chloride salts. Consequently, the cycle utilizing MgCl\({}_{2}\)-KCl salts improves the \(SP\) of the turbine, main compressor, and recompressor by 11.63%, 15.74%, and 20.12%, respectively.  
Figure 8: Comparison of \(UA\) for the HTR and LTR at different pressure ratios.  
Figure 9: Comparison of \(UA\) for the IHE and PC at different pressure ratios.  
Figure (a)a illustrates the storage volume required per hour at various pressure ratios. Although chloride salts exhibit a larger temperature difference, as shown in Figure (b)b, the storage volume required is higher for pressure ratios below 3.175. For both types of molten salts, the minimum storage volume is achieved at the pressure ratio that maximizes the temperature difference between the two tanks. In the case of MgCl\({}_{2}\)-KCl salts, the minimum storage volume is 87.6 m\({}^{3}\), corresponding to a temperature difference of 233 K at a pressure ratio of 3.05. Meanwhile, for solar salts, the minimum volume is 84.29 m\({}^{3}\), with a temperature difference of 187.7 K at a pressure ratio of 3. Consequently, the utilisation of MgCl\({}_{2}\)-KCl salts results in an augmentation of the temperature difference by 24.13%, whilst necessitating a storage volume that is 3.28% larger.  
Figure 11: Comparison of storage volume required per hour and temperature difference at different pressure ratios.  
Figure 10: Comparison of \(SP\) of the turbine, main compressor and recompressor compressor at different pressure ratios.