As inexpensive and environmentally friendly technology, humidification-dehumidification (HDH) is an ideal candidate for water desalination due to its simple design and low energy requirements. With the ability to treat various types of compromised waters, the addition of a packed-bed medium enhances the desalination efficiency and system compactness, making direct-contact packed-bed HDH desalination systems a perfect fit for geographically distributed water desalination units and building integration.The first part of this thesis focuses on modeling the behavior of a desalination unit and its integration with solar thermal systems, with a one-dimensional mathematical model developed and validated experimentally. Machine learning regression techniques are used to develop a data-driven surrogate model, which accurately predicts desalination performance but requires a larger dataset for high fidelity. A comprehensive assessment is carried out for the integration of an HDH system with a solar chimney, resulting in solar desalination chimneys. The assessment suggests that the pressure drop is a critical factor in the system's performance. A direct-contact packed-bed condenser shows a prominent desalination capacity. Small-scale configurations are ideal for household freshwater needs, while the large-scale can be implemented as sporadic water treatment plants in rural areas. Solar air heater systems are also studied for potential integration with desalination units, with an experimental flat plate solar air heater built and validated with 3D computational and 1D mathematical models. The investigation suggests that although the integrated system is more efficient (both thermal and desalination) compared to that of the solar desalination chimney, the dependency of the system on energy sources for the circulation of water and air is a significant drawback. This dependency can limit the system's autonomy and increase its operational costs. The second part of this thesis investigates the integration of desalination units with buildings, specifically greenhouses. The greenhouse is integrated with a transparent solar water heater as a roof that absorbs the NIR waveband to increase the temperature of used or saline water and then passes the essential wavebands for plant growth. The hot water then flows through a water-treatment unit to produce potable water. Experimental pilots of the solar water heater are built, and models are developed to predict the behavior of the solar water panel meticulously. To incorporate the impact of spectral variation on lettuce as the case study, a dynamic growth model is developed that quantifies light spectrum variations. Changes in the light spectrum are accounted for via a new light-use efficiency parameter in the plant growth model. Then, several models are coupled to predict the behavior of an integrated greenhouse with a transparent solar water heater as a roof, a water treatment unit, and a spectral-incorporated plant growth model for lettuce in Phoenix, AZ. The models suggest that the transparent solar water heater on the roof reduces greenhouse ventilation load by about 30%, and the water treatment unit produces 35-40 kg of potable water daily, sufficient for single-row cultivation of lettuce. The integrated greenhouse has the potential to produce an average of 300 kg of fresh lettuce each month during the growth period, according to the plant growth model.
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