Karima Hijjaji - Academia.edu (original) (raw)

Papers by Karima Hijjaji

Research paper thumbnail of Using DOE and RSM procedures to analyze and model a spray evaporation type solar still

International Journal of Energy and Environmental Engineering, 2021

The lower productivity of the conventional solar still requires bringing modifications to this sy... more The lower productivity of the conventional solar still requires bringing modifications to this system. The proposed modification in this work consists of coupling water spray and ambient air injection, which may enhance the water–air surface contact area as it plays a crucial role in the performance in such a device and, consequently, increases the still performances. Response surface methodology (RSM) model is derived from an experimental test set up using the design of experiment procedure to investigate the binary interaction effects of the operating parameters, i.e., spraying height, inlet water temperature, and water and air flowrates. Based on RSM results, a simple polynomial statistical model is stated in this investigation to determine and maximize the amount of evaporated water from solar still based on the four considered input factors. An excellent fitting is attained between the predicted results derived from the statistical model and the experimental results. The performance of this model was also validated using the variance analysis approach. The findings indicate that the main influencing parameters in the order of impact on the system productivity is ambient air mass flow, saltwater temperature, sprayed water mass flow and sprayer height. The binary interaction effects of the variables were considered and illustrated for design recommendations. Within the studied ranges, the hourly productivity varies from 1.91 to 7.9 kg/h m2 for a water temperature between 40 and 70 °C.

Research paper thumbnail of Study of a solar HDH desalination unit powered greenhouse for water and humidity self-sufficiency

International Journal of Energy and Environmental Engineering

This study investigates the performances of a self-sufficient greenhouse powered by a solar humid... more This study investigates the performances of a self-sufficient greenhouse powered by a solar humidification-dehumidification desalination unit. It aims to achieve an overall integrated system that produces enough fresh water to cover the irrigation demand as well as the air humidification needs of the greenhouse. The humidification-dehumidification operation was numerically simulated using the developed model along with the greenhouse microclimate. The greenhouse model was validated through an experimental real-scale greenhouse. To make the proposed system more flexible, an auxiliary control system is used to easily monitor the greenhouse needs and ensure its satisfaction. The findings revealed that the integrated system, with its two main subsystems and its regulation device, successfully ensures the greenhouse irrigation, the humidification needs and provides an optimal plant growth. For the case study, i.e. cucurbit greenhouse situated at El Hamma (Tunisia), the desalination system can cover more than 200% of the greenhouse water irrigation needs while keeping the greenhouse inside air at a humidity level of 60% at least. The maximum productivity and the best energy efficiency are respectively 5.1 m 3 /day and 63.25%.

Research paper thumbnail of Using DOE and RSM procedures to analyze and model a spray evaporation type solar still

International Journal of Energy and Environmental Engineering

The lower productivity of the conventional solar still requires bringing modifications to this sy... more The lower productivity of the conventional solar still requires bringing modifications to this system. The proposed modification in this work consists of coupling water spray and ambient air injection, which may enhance the water–air surface contact area as it plays a crucial role in the performance in such a device and, consequently, increases the still performances. Response surface methodology (RSM) model is derived from an experimental test set up using the design of experiment procedure to investigate the binary interaction effects of the operating parameters, i.e., spraying height, inlet water temperature, and water and air flowrates. Based on RSM results, a simple polynomial statistical model is stated in this investigation to determine and maximize the amount of evaporated water from solar still based on the four considered input factors. An excellent fitting is attained between the predicted results derived from the statistical model and the experimental results. The perfor...

Research paper thumbnail of Determination of heat and mass transfer coefficients in a spray humidifier of a humidification-dehumidification desalination system

An innovative design approach consists of using a saline water spray humidifier to improve the pe... more An innovative design approach consists of using a saline water spray humidifier to improve the performance of the humidification–dehumidification water desalination system, where hot water was sprayed from the top and air was supplied from the bottom of the humidifier. Before scaling a unit of this type, it is necessary to get sufficient information about the heat and mass transfer process that occurs in the unit. A prototype desalination unit has been developed and used to fulfill the main objective of this research which is to evaluate the mass and heat transfer coefficients in the humidifier. As well, the effect of salt water flow rate, water temperature, air flow rate and position of the water spray are examined in order to optimize the operating conditions. A quadratic model estimating the performance of the humidifier was developed and validated using the design of experiment analysis and variance approach. A response surface methodology was used to correlate and assess the in...

Research paper thumbnail of Using DOE and RSM procedures to analyze and model a spray evaporation type solar still

International Journal of Energy and Environmental Engineering, 2021

The lower productivity of the conventional solar still requires bringing modifications to this sy... more The lower productivity of the conventional solar still requires bringing modifications to this system. The proposed modification in this work consists of coupling water spray and ambient air injection, which may enhance the water–air surface contact area as it plays a crucial role in the performance in such a device and, consequently, increases the still performances. Response surface methodology (RSM) model is derived from an experimental test set up using the design of experiment procedure to investigate the binary interaction effects of the operating parameters, i.e., spraying height, inlet water temperature, and water and air flowrates. Based on RSM results, a simple polynomial statistical model is stated in this investigation to determine and maximize the amount of evaporated water from solar still based on the four considered input factors. An excellent fitting is attained between the predicted results derived from the statistical model and the experimental results. The performance of this model was also validated using the variance analysis approach. The findings indicate that the main influencing parameters in the order of impact on the system productivity is ambient air mass flow, saltwater temperature, sprayed water mass flow and sprayer height. The binary interaction effects of the variables were considered and illustrated for design recommendations. Within the studied ranges, the hourly productivity varies from 1.91 to 7.9 kg/h m2 for a water temperature between 40 and 70 °C.

Research paper thumbnail of Study of a solar HDH desalination unit powered greenhouse for water and humidity self-sufficiency

International Journal of Energy and Environmental Engineering

This study investigates the performances of a self-sufficient greenhouse powered by a solar humid... more This study investigates the performances of a self-sufficient greenhouse powered by a solar humidification-dehumidification desalination unit. It aims to achieve an overall integrated system that produces enough fresh water to cover the irrigation demand as well as the air humidification needs of the greenhouse. The humidification-dehumidification operation was numerically simulated using the developed model along with the greenhouse microclimate. The greenhouse model was validated through an experimental real-scale greenhouse. To make the proposed system more flexible, an auxiliary control system is used to easily monitor the greenhouse needs and ensure its satisfaction. The findings revealed that the integrated system, with its two main subsystems and its regulation device, successfully ensures the greenhouse irrigation, the humidification needs and provides an optimal plant growth. For the case study, i.e. cucurbit greenhouse situated at El Hamma (Tunisia), the desalination system can cover more than 200% of the greenhouse water irrigation needs while keeping the greenhouse inside air at a humidity level of 60% at least. The maximum productivity and the best energy efficiency are respectively 5.1 m 3 /day and 63.25%.

Research paper thumbnail of Using DOE and RSM procedures to analyze and model a spray evaporation type solar still

International Journal of Energy and Environmental Engineering

The lower productivity of the conventional solar still requires bringing modifications to this sy... more The lower productivity of the conventional solar still requires bringing modifications to this system. The proposed modification in this work consists of coupling water spray and ambient air injection, which may enhance the water–air surface contact area as it plays a crucial role in the performance in such a device and, consequently, increases the still performances. Response surface methodology (RSM) model is derived from an experimental test set up using the design of experiment procedure to investigate the binary interaction effects of the operating parameters, i.e., spraying height, inlet water temperature, and water and air flowrates. Based on RSM results, a simple polynomial statistical model is stated in this investigation to determine and maximize the amount of evaporated water from solar still based on the four considered input factors. An excellent fitting is attained between the predicted results derived from the statistical model and the experimental results. The perfor...

Research paper thumbnail of Determination of heat and mass transfer coefficients in a spray humidifier of a humidification-dehumidification desalination system

An innovative design approach consists of using a saline water spray humidifier to improve the pe... more An innovative design approach consists of using a saline water spray humidifier to improve the performance of the humidification–dehumidification water desalination system, where hot water was sprayed from the top and air was supplied from the bottom of the humidifier. Before scaling a unit of this type, it is necessary to get sufficient information about the heat and mass transfer process that occurs in the unit. A prototype desalination unit has been developed and used to fulfill the main objective of this research which is to evaluate the mass and heat transfer coefficients in the humidifier. As well, the effect of salt water flow rate, water temperature, air flow rate and position of the water spray are examined in order to optimize the operating conditions. A quadratic model estimating the performance of the humidifier was developed and validated using the design of experiment analysis and variance approach. A response surface methodology was used to correlate and assess the in...