Sharif Digital Repository

Providing fresh water for domestic and agricultural purposes has become one of the most pressing issues of the present century. Due to the dependency of conventional desalination on fossil fuels, these methods are associated with carbon dioxide and other greenhouse gas emissions. Therefore, renewable energy-based desalination systems have come to the fore. This study scrutinizes the performance of the solar Humidification-Dehumidification (HDH) desalination systems with subsurface condensers. In this system, solar energy evaporates water, and subsurface condensers condense water vapor into fresh water. Therefore, this system uses two renewable solar and geothermal energy. Due to the lack of... 

The present thesis aimed to study a novel heat pump integrated humidification-dehumidification (HDH-HP) desalination system. A theoretical outline was proposed for the first time to examine the design and off-design performance of HDH-HP cycles via the compressor characteristics method. In this regard, the variations in heat pump performance were modeled in different operating conditions for a fixed-size system. To fabricate a compact HDH-HP system, an evaporative condenser was designed and used instead of a separate humidifier, heater, and air/water-cooled condensers find in previous HDH-HP systems. Meanwhile, the air dehumidification process in this work directly occurred inside the heat... 

In this research, an attempt has been made to construct an industrial-scale humidification-dehumidification water desalination system using the results of previous laboratory-scale studies and experiments by researchers. The constructed system consists of two separate sections, each containing two stages for humidification and dehumidification. It is noteworthy that only the bubble column method has been utilized in this system, with each stage containing ten layers to increase the moisture exchange between air and water. In this study, the effects of parameters such as the structure of the trays in each layer, the water height in each layer, air flow rate, and the temperature at various... 

The main objective of this study is to develop a hybrid desalination system combining reverse osmosis and humidification-dehumidification with the goal of near-zero liquid discharge. Two conventional humidification methods (packed bed and bubble column) were examined to achieve this goal. Notably, the studied system is a small-scale, off-grid system suitable for use in energy-scarce areas. This research involved numerical and experimental studies of the hybrid desalination system. Both humidifier types were studied to understand the humidification-dehumidification cycle performance better. The results indicated that the reverse osmosis cycle operates with a higher recovery rate by increasing... 

Humidification-dehumidification (HDH) systems are known for their simple structure, low-grade energy consumption, ability to work with saline water with high salinity, and suitability for remote areas with limited freshwater resources. This study uses a numerical method that includes thermodynamic analyses (involving heat and mass transfer modeling) and economic aspects of a humidification-dehumidification system with a packed bed humidifier and a heat pump (HP) unit. Since the air leaving the humidifier is usually not fully saturated, the Poppe model is used to design the humidifier. This study evaluates the effects of various parameters, including mass flow ratio (MR), different...