## 5 Conclusions  
To make the solar desalination system more effective, scientists have made several changes to the solar desalination model. The novelty of the current study is to obtain a higher production rate of daily fresh water in the HD solar desalination system through developing and simulating three design configurations of the process and integrating into the optimal configuration a regulation algorithm to further optimize its freshwater production. The results obtained indicate that the maximum freshwater output of about 18 kg/day is obtained with the third configuration, and this value is also increased by nearly 33% with the implementation of the proposed regulation algorithm.The atomization of such a type of solar desalination system, together with the development of a regulating algorithm for the removal of minerals and salts in the system, is an extension of the current study. Conceptualization, K.Z. ; completed literature review, K.Z. and K.A.A. ; investigation, K.Z. ; formal analysis, K.Z. and K.A.A. ; software, K.Z. and K.A.A. ; cost analysis, K.A.A. ; writing--review and editing, K.Z. and K.A.A. All authors have read and agreed to the published version of the manuscript. This research received no external funding. The authors wish to express their deep gratitude to [PERSON], [PERSON], and Engineer [PERSON] for their help in comprehensively realizing this research and discussing the obtained results. The authors declare no conflict of interest. \begin{table}
\begin{tabular}{l c c c} \hline \hline
**Components (Unit)** & **Quantity** & **Unitary Cost** & **Total Cost** \\ \hline Air solar collector & 16 m\({}^{2}\) & 208 \(\upepsilon\)/m\({}^{2}\) & 3328 \(\upepsilon\) \\ Water solar collector & 12 m\({}^{2}\) & 235 \(\upepsilon\)/m\({}^{2}\) & 2820 \(\upepsilon\) \\ Condensation tower & 1 & 1490 \(\upepsilon\) & 1490 \(\upepsilon\) \\ Humidifier & 1 & 750 \(\upepsilon\) & 750 \(\upepsilon\) \\ Evaporation tower & 1 & 1000 \(\upepsilon\) & 1000 \(\upepsilon\) \\ Immersed pump & 2 & 111 \(\upepsilon\) & 222 \(\upepsilon\) \\ Fan & 1 & 277 \(\upepsilon\) & 277 \(\upepsilon\) \\ Ducts & - & 888 \(\upepsilon\) & 888 \(\upepsilon\) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Investment cost of each component involved in the desalination unit. List of Symbols
* aair-water exchanger area (m\({}^{2}\))
* bwidth of air solar collector
* Cspecific heat (J/(kg-K))
* Dewater mass velocity in the condensation tower (kg/(m\({}^{2}\)-s))
* hheat transfer coefficient (J/(kg-K))
* hgair heat transfer coefficient at the air-water interface(W/(m\({}^{2}\)-K))
* hewater heat transfer coefficient at the air-water interface(W/(m\({}^{2}\)-K))
* lwidthof water solar collector (m)
* Llength of air solar collector (m)
* Isolar flux (W/m\({}^{2}\))
* Kthermal conductivity (W/(m-K))
* Kmwater vapor mass transfer coefficient at the air-water interface (kg/(m\({}^{2}\)-s))
* Mmass (kg)
* mmass flow rate (kg/s)
* m\({}_{c}\) fresh water production (kg/s)
* m\({}_{gt}\)total mass velocity of moist air in the condenser (kg/(m\({}^{2}\)-s))
* Sabsorber surface (m\({}^{2}\))
* Ttemperature (K)
* T\({}_{i}\)temperature at the air-water interface (K)
* Uoverall heat transfer coefficient in the condensation tower (W/ (m\({}^{2}\)-K))
* U\({}_{loss}\)overall energy loss from the absorber to outside (W/ (m\({}^{2}\)-K))
* Wair humidity (kg water/kg dry air)
* Wisaturation humidity (kg water/kg dry air)
* zcoordinate in the flow direction (m)
* xcoordinate in the flow direction (m)
* _Greek_
* \(\alpha\)absorptance of the collector absorber surface
* \(\lambda_{0}\)latent heat of water evaporation (J/kg)
* \(\tau\)transmittance
* _Subscripts_
* 1 tower bottom
* 2 tower top
* air
* amb  
* [PERSON] et al. (2016) [PERSON]; [PERSON]; [PERSON] [PERSON]; [PERSON]; [PERSON] Recent advances in humidification dehumidification (HDH) desalination processes: Improved designs and productivity. _Renew. Sustain. Energy Rev._**2016**, _57_, 929-944.