## 3 System Layout
### Experimental Results  
In this experiment, 1 Kg of NaCl (Institute for Thermal Process Engineering at the TU Hamburg-Harburg, Hamburg, Germany) was dissolved in 80 L of distilled water (H\({}_{2}\)O). This means that 1.25 wt% of NaCl was used, as the density of the distilled water was equal to 997 Kg/m\({}^{3}\). Due to the setup configurations, the minimum required pressure to operate the reverse osmosis unit was 40 bar. In this regard, the applied pressure range was 40-60 bar, with a time interval of two minutes for each trial. Six iterations were carried out. Table 2 illustrates the temperature results of the six trials and flow rates. The conductivity values are depicted in Figure 7.  
Figure 6: CE 530 RO-Setup. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Trial Number**} & \multicolumn{2}{c}{**Raw-water**} & \multirow{2}{*}{**Total Flow Rate**} & \multicolumn{2}{c}{**Flow Rate**} & \multicolumn{2}{c}{**Temp. Raw-Water**} & \multicolumn{1}{c}{**Temp.**} & \multicolumn{1}{c}{**Temp.**} \\  & **Pressure [\(bar\)]** & & **Retenate [\%\(\frac{L}{\text{min}}\)]** & **Permeate [\%\(\frac{L}{\text{min}}\)]** & **Permeate [\%\(\frac{L}{\text{min}}\)]** & **[\%\(\frac{L}{\text{min}}\)]** & **[\%\(\frac{L}{\text{min}}\)]** & **[\%\(\frac{L}{\text{min}}\)]** \\ \hline
1 & 40 & 0.312 & 63.78 & 36.22 & 24.8 & 37 & 32.1 \\
2 & 44 & 0.341 & 61.58 & 38.42 & 24.9 & 37.1 & 33.2 \\
3 & 48 & 0.37 & 58.11 & 41.89 & 25 & 37.8 & 34 \\
4 & 52 & 0.385 & 57.92 & 42.08 & 25.2 & 38.4 & 36.5 \\
5 & 56 & 0.395 & 57.22 & 42.78 & 25.5 & 38.8 & 37.1 \\
6 & 58 & 0.403 & 57.32 & 42.68 & 26.1 & 39.6 & 38.5 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Flow rate and temperature of the experimental trials. Figure 7: Water Conductivity (mS/cm). From Table 2, it can be shown that the applied pressure increased from one trial to another until it reached 58 as a maximum. Moreover, increasing the pressure increased the production of desalinated water. Thus, increasing the applied pressure increased the volumetric amount of desalinated water and decreased its salinity. It is noticeable that with increased pressure, the flow rate of the retenate water also increased. As shown also, both retenate and permeate flow rates increased with increasing pressure, but the separation percentage for the retenate water decreased from 63% to 57%, while the separation percentage of the permeate water increased from 36% to 42.6%. As shown in Figure 7, the conductivity of the raw water stayed constant; the reason behind this is the feeding back of the retenate water and the permeate water to the tank of raw water. Moreover, the raw water tank was attached to a sterilizer, which was used to help in keeping the conductivity constant while adding retenate and permeate water synchronously back to it. Keeping the conductivity of the raw water constant is important to accurately investigate the relation between the applied pressure and the salinity, which have been noticed to be directly proportional. As is also shown in Figure 7, the conductivity, which is an indicator of the salinity, of the permeate water decreased with increasing applied pressure. Increasing applied pressure means increasing the consumed power, but also decreasing the amount of dissolved salts in the permeate water. Furthermore, it can be noticed that the salinity of the retenate water increased with increasing pressure. Adding the salinity of the retenate water to the salinity of the permeate water, while taking into account the flow rate for both of them, will clearly be equal to 23.2 mS/cm, which is the conductivity of the raw water as it is shown. Figure 8 illustrates and concludes the relationship between the pressure of the raw water and three important factors: conductivity, permeate flow rate, and power consumption. The power consumption rates shown in Figure 8 were calculated using Equation (1).