Amine HAJJI | Mohamed V University in Rabat (original) (raw)

Papers by Amine HAJJI

International Journal of Engineering Research in Africa

Anaerobic digestion is a promising technology due to its significant economic and environmental p... more Anaerobic digestion is a promising technology due to its significant economic and environmental potential. Nevertheless, its development is a substantial challenge for researchers since this biochemical process is difficult to predict due to the many reactions involved. Thus, mathematical modeling becomes necessary to analyze the fermentation process and determine the complex kinetic parameters to identify and predict the system's performance under the most varied conditions. This research aims to apply the AM2 model to simulate the anaerobic digestion process of municipal solid waste. The experimental results obtained from our previous research work were used for identifying the parameters of the AM2 model and for its validation by the cross-validation method. Simulations showed that the model could effectively reproduce the dynamics of the evolution of the anaerobic digestion process with reasonable accuracy.

International Journal of Renewable Energy Development, 2023

Anaerobic digestion is a complex process whose understanding, optimization, and development requi... more Anaerobic digestion is a complex process whose understanding, optimization, and development require mathematical modeling to simulate digesters' operation under various conditions. Consequently, the present work focuses on developing a new and improved model called "AM2P" derived from the AM2 model. This new model incorporates surface-based kinetics (SBK) into the overall simulation process to transform the system into three stages: hydrolysis, acidogenesis, and methanogenesis. Experimental data from our previous work were used to identify the AM2 and AM2P models' parameters. Simulations showed that the AM2P model satisfactorily represented the effect of the hydrolysis phase on the anaerobic digestion process, since simulated values for acidogenic (X1) and methanogenic (X2) biomass production revealed an increase in their concentration as a function of particle size reduction, with a maximum concentration of the order of 5.5 g/l for X1 and 0.8 g/l for X2 recorded for the case of the smallest particle size of 0.5 cm, thus accurately representing the effect of substrate particle disintegration on biomass production dynamics and enabling the process of anaerobic digestion to be qualitatively reproduced. The AM2P model also provided a more accurate response, with less deviation from the experimental data; this was the case for the evolution of methane production, where the coefficient of determination (R 2) was higher than 0.8, and the root-mean-square error (RMSE) was less than 0.02.

International Journal of Engineering Research in Africa, 2023

Anaerobic digestion is a promising technology due to its significant economic and environmental p... more Anaerobic digestion is a promising technology due to its significant economic and environmental potential. Nevertheless, its development is a substantial challenge for researchers since this biochemical process is difficult to predict due to the many reactions involved. Thus, mathematical modeling becomes necessary to analyze the fermentation process and determine the complex kinetic parameters to identify and predict the system's performance under the most varied conditions. This research aims to apply the AM2 model to simulate the anaerobic digestion process of municipal solid waste. The experimental results obtained from our previous research work were used for identifying the parameters of the AM2 model and for its validation by the cross-validation method. Simulations showed that the model could effectively reproduce the dynamics of the evolution of the anaerobic digestion process with reasonable accuracy.

Scientific African

Anaerobic digestion is a promising process with many advantages on the environmental and energy l... more Anaerobic digestion is a promising process with many advantages on the environmental and energy level, yet, it remains little exploited, due to the lack of control of the operating parameters of this process, because of the complexity of the biochemical reactions involved. Among the brakes on the development of this sector, we cite the hydrolysis stage, which is the most kinetically limiting phase of the fermentation process. The present work aims to study the effect of thermochemical pretreatment, at temperatures ranging from 55 °C to 65 °C, with a pH ranging from 8 to 12 and a retention time of 6 to 24 h, on the improvement of substrate hydrolysis, while evaluating the solubilization rate and the biogas yield. The results showed that the applied pretreatment was successful in improving the efficiency of the anaerobic digestion process, by improving the solubilization rate of the substrate, with the greatest rate recorded of 67.1%, which generates a significant increase in the proportion of organic matter that can be converted into biogas. A considerable improvement of the biogas production and the methane rate was noted for all the experiments carried out; the most biogas production of 0.77 mL. g − 1 VS, as well as of the methane rate of 68%, was recorded for the pretreatment conditions at a temperature of 65 °C, a pH of 10 and a retention time of 24 h, which is higher by 180% in biogas, and 19.2% in methane, compared to the case of the non-pretreated substrate.

2016 3rd International Conference on Renewable Energies for Developing Countries (REDEC), 2016

This paper presents semi-empirical models for estimating Global Horizontal Irradiance (GHI) under... more This paper presents semi-empirical models for estimating Global Horizontal Irradiance (GHI) under specific sky conditions. We analysed the models to estimate global horizontal irradiance measurements in four Moroccan regions. The data consists of a one-year period at four solar irradiance monitoring stations located in the south and south-east of the country, Missour, Erfoud, Zagora and Tantan. Several empirical clear sky models are considered for a Moroccan case study. These models are validated using (GHI) measurements from different stations over different time periods. The disagreement between the various measurements of GHI and the semi-empirical models used for the estimation of radiation in atmospheric physics and radiative transfer modeling is sometimes significant, especially in the presence of clouds or large concentration of aerosols. A good agreement is noticed between the measured values and those estimated by some models.

The effect of thermochemical pretreatment on anaerobic digestion efficiency of municipal solid waste under mesophilic conditions, 2022

Anaerobic digestion is a promising process with many advantages on the environmental and energy l... more Anaerobic digestion is a promising process with many advantages on the environmental and energy level, yet, it remains little exploited, due to the lack of control of the operating parameters of this process, because of the complexity of the biochemical reactions involved. Among the brakes on the development of this sector, we cite the hydrolysis stage, which is the most kinetically limiting phase of the fermentation process. The present work aims to study the effect of thermochemical pretreatment, at temperatures ranging from 55 °C to 65 °C, with a pH ranging from 8 to 12 and a retention time of 6 to 24 h, on the improvement of substrate hydrolysis, while evaluating the solubilization rate and the biogas yield. The results showed that the applied pretreatment was successful in improving the efficiency of the anaerobic digestion process, by improving the solubilization rate of the substrate, with the greatest rate recorded of 67.1%, which generates a significant increase in the proportion of organic matter that can be converted into biogas. A considerable improvement of the biogas production and the methane rate was noted for all the experiments carried out; the most biogas production of 0.77 mL. g − 1 VS, as well as of the methane rate of 68%, was recorded for the pretreatment conditions at a temperature of 65 °C, a pH of 10 and a retention time of 24 h, which is higher by 180% in biogas, and 19.2% in methane, compared to the case of the non-pretreated substrate.

Journal of Thermal Science and Engineering Applications, 2022

In the present work, experimental and numerical studies are conducted to identify and improve the... more In the present work, experimental and numerical studies are conducted to identify and improve the thermal properties of the most commonly used hollow concrete blocks in Morocco. The experimental approach consists in characterizing the thermal conductivity and thermal capacity of the basic materials using the guarded hot plate and the differential calorimeter, respectively. The obtained properties have been exploited as input data in the numerical approach in order to investigate the coupled heat transfers through the honeycomb blocks using the approximation calculation method suggested by EN ISO 6946, and the three-dimensional numerical simulations using the commercial software Ansys Fluent. The obtained results showed that the average differences between the 1D and 3D calculations are less than 7.5% concerning the five type studies. In addition, the increase in the width and number of cavities leads to gain a significant decrease in heat loss and an increase in thermal resistance. ...

2021 9th International Renewable and Sustainable Energy Conference (IRSEC), Nov 23, 2021

Journal of Thermal Science and Engineering Applications, 2022

In the present work, experimental and numerical studies are conducted to identify and improve the... more In the present work, experimental and numerical studies are conducted to identify and improve the thermal properties of the most commonly used hollow concrete blocks in Morocco. The experimental approach consists in characterizing the thermal conductivity and thermal capacity of the basic materials using the guarded hot plate and the differential calorimeter, respectively. The obtained properties have been exploited as input data in the numerical approach in order to investigate the coupled heat transfers through the honeycomb blocks using the approximation calculation method suggested by EN ISO 6946, and the three-dimensional numerical simulations using the commercial software Ansys Fluent. The obtained results showed that the average differences between the 1D and 3D calculations are less than 7.5% concerning the five type studies. In addition, the increase in the width and number of cavities leads to gain a significant decrease in heat loss and an increase in thermal resistance. ...

2016 3rd International Conference on Renewable Energies for Developing Countries (REDEC), 2016

Considering the importance of reducing energy consumption in the Moroccan building sector, this w... more Considering the importance of reducing energy consumption in the Moroccan building sector, this work deals with a preliminary analysis of the typology and the evolution of the final energy consumption in this sector. The modes of construction and the evolution of the park for different types of housing were also considered. The purpose is also to highlight the potential of the thermal insulation demand.

2014 International Renewable and Sustainable Energy Conference (IRSEC), 2014

Morocco currently witnesses an important economic and social development, accompanied in parallel... more Morocco currently witnesses an important economic and social development, accompanied in parallel to an exponential energy demand which increases the bill of the state, since 95% of the energy is imported from abroad. It also gives a high priority to the development of renewable energies including biogas, given its important deposit and its environmental, economic and social interest. With its energy potential, biogas may figure more prominently in the energy equation, if the optimization of the anaerobic digestion process improves more. To contribute to the improvement of this process, the objective adopted by the present work is to study the effect of different temperatures belonging to the mesophile plan on the performance of production of biogas as well as its content in methane and carbon dioxide. With this aim in mind, a digester with a capacity of 14 liters has been used, equipped with an integrated control device. The digestion temperatures were set at 35, 37 and 40°C, with a time of stay of 21 days. For all experiments, the size of the particles of municipal solid waste has been reduced to 10 mm. The obtained results show a high correlation between the temperature, the production of biogas and the content of methane, with an improvement of the quantity and the quality of biogas of the product registered for a temperature of digestion of 40 °C.

International Journal of Engineering Research in Africa

Anaerobic digestion is a promising technology due to its significant economic and environmental p... more Anaerobic digestion is a promising technology due to its significant economic and environmental potential. Nevertheless, its development is a substantial challenge for researchers since this biochemical process is difficult to predict due to the many reactions involved. Thus, mathematical modeling becomes necessary to analyze the fermentation process and determine the complex kinetic parameters to identify and predict the system's performance under the most varied conditions. This research aims to apply the AM2 model to simulate the anaerobic digestion process of municipal solid waste. The experimental results obtained from our previous research work were used for identifying the parameters of the AM2 model and for its validation by the cross-validation method. Simulations showed that the model could effectively reproduce the dynamics of the evolution of the anaerobic digestion process with reasonable accuracy.

International Journal of Renewable Energy Development, 2023

Anaerobic digestion is a complex process whose understanding, optimization, and development requi... more Anaerobic digestion is a complex process whose understanding, optimization, and development require mathematical modeling to simulate digesters' operation under various conditions. Consequently, the present work focuses on developing a new and improved model called "AM2P" derived from the AM2 model. This new model incorporates surface-based kinetics (SBK) into the overall simulation process to transform the system into three stages: hydrolysis, acidogenesis, and methanogenesis. Experimental data from our previous work were used to identify the AM2 and AM2P models' parameters. Simulations showed that the AM2P model satisfactorily represented the effect of the hydrolysis phase on the anaerobic digestion process, since simulated values for acidogenic (X1) and methanogenic (X2) biomass production revealed an increase in their concentration as a function of particle size reduction, with a maximum concentration of the order of 5.5 g/l for X1 and 0.8 g/l for X2 recorded for the case of the smallest particle size of 0.5 cm, thus accurately representing the effect of substrate particle disintegration on biomass production dynamics and enabling the process of anaerobic digestion to be qualitatively reproduced. The AM2P model also provided a more accurate response, with less deviation from the experimental data; this was the case for the evolution of methane production, where the coefficient of determination (R 2) was higher than 0.8, and the root-mean-square error (RMSE) was less than 0.02.

International Journal of Engineering Research in Africa, 2023

Anaerobic digestion is a promising technology due to its significant economic and environmental p... more Anaerobic digestion is a promising technology due to its significant economic and environmental potential. Nevertheless, its development is a substantial challenge for researchers since this biochemical process is difficult to predict due to the many reactions involved. Thus, mathematical modeling becomes necessary to analyze the fermentation process and determine the complex kinetic parameters to identify and predict the system's performance under the most varied conditions. This research aims to apply the AM2 model to simulate the anaerobic digestion process of municipal solid waste. The experimental results obtained from our previous research work were used for identifying the parameters of the AM2 model and for its validation by the cross-validation method. Simulations showed that the model could effectively reproduce the dynamics of the evolution of the anaerobic digestion process with reasonable accuracy.

Scientific African

Anaerobic digestion is a promising process with many advantages on the environmental and energy l... more Anaerobic digestion is a promising process with many advantages on the environmental and energy level, yet, it remains little exploited, due to the lack of control of the operating parameters of this process, because of the complexity of the biochemical reactions involved. Among the brakes on the development of this sector, we cite the hydrolysis stage, which is the most kinetically limiting phase of the fermentation process. The present work aims to study the effect of thermochemical pretreatment, at temperatures ranging from 55 °C to 65 °C, with a pH ranging from 8 to 12 and a retention time of 6 to 24 h, on the improvement of substrate hydrolysis, while evaluating the solubilization rate and the biogas yield. The results showed that the applied pretreatment was successful in improving the efficiency of the anaerobic digestion process, by improving the solubilization rate of the substrate, with the greatest rate recorded of 67.1%, which generates a significant increase in the proportion of organic matter that can be converted into biogas. A considerable improvement of the biogas production and the methane rate was noted for all the experiments carried out; the most biogas production of 0.77 mL. g − 1 VS, as well as of the methane rate of 68%, was recorded for the pretreatment conditions at a temperature of 65 °C, a pH of 10 and a retention time of 24 h, which is higher by 180% in biogas, and 19.2% in methane, compared to the case of the non-pretreated substrate.

2016 3rd International Conference on Renewable Energies for Developing Countries (REDEC), 2016

This paper presents semi-empirical models for estimating Global Horizontal Irradiance (GHI) under... more This paper presents semi-empirical models for estimating Global Horizontal Irradiance (GHI) under specific sky conditions. We analysed the models to estimate global horizontal irradiance measurements in four Moroccan regions. The data consists of a one-year period at four solar irradiance monitoring stations located in the south and south-east of the country, Missour, Erfoud, Zagora and Tantan. Several empirical clear sky models are considered for a Moroccan case study. These models are validated using (GHI) measurements from different stations over different time periods. The disagreement between the various measurements of GHI and the semi-empirical models used for the estimation of radiation in atmospheric physics and radiative transfer modeling is sometimes significant, especially in the presence of clouds or large concentration of aerosols. A good agreement is noticed between the measured values and those estimated by some models.

The effect of thermochemical pretreatment on anaerobic digestion efficiency of municipal solid waste under mesophilic conditions, 2022

Anaerobic digestion is a promising process with many advantages on the environmental and energy l... more Anaerobic digestion is a promising process with many advantages on the environmental and energy level, yet, it remains little exploited, due to the lack of control of the operating parameters of this process, because of the complexity of the biochemical reactions involved. Among the brakes on the development of this sector, we cite the hydrolysis stage, which is the most kinetically limiting phase of the fermentation process. The present work aims to study the effect of thermochemical pretreatment, at temperatures ranging from 55 °C to 65 °C, with a pH ranging from 8 to 12 and a retention time of 6 to 24 h, on the improvement of substrate hydrolysis, while evaluating the solubilization rate and the biogas yield. The results showed that the applied pretreatment was successful in improving the efficiency of the anaerobic digestion process, by improving the solubilization rate of the substrate, with the greatest rate recorded of 67.1%, which generates a significant increase in the proportion of organic matter that can be converted into biogas. A considerable improvement of the biogas production and the methane rate was noted for all the experiments carried out; the most biogas production of 0.77 mL. g − 1 VS, as well as of the methane rate of 68%, was recorded for the pretreatment conditions at a temperature of 65 °C, a pH of 10 and a retention time of 24 h, which is higher by 180% in biogas, and 19.2% in methane, compared to the case of the non-pretreated substrate.

Journal of Thermal Science and Engineering Applications, 2022

In the present work, experimental and numerical studies are conducted to identify and improve the... more In the present work, experimental and numerical studies are conducted to identify and improve the thermal properties of the most commonly used hollow concrete blocks in Morocco. The experimental approach consists in characterizing the thermal conductivity and thermal capacity of the basic materials using the guarded hot plate and the differential calorimeter, respectively. The obtained properties have been exploited as input data in the numerical approach in order to investigate the coupled heat transfers through the honeycomb blocks using the approximation calculation method suggested by EN ISO 6946, and the three-dimensional numerical simulations using the commercial software Ansys Fluent. The obtained results showed that the average differences between the 1D and 3D calculations are less than 7.5% concerning the five type studies. In addition, the increase in the width and number of cavities leads to gain a significant decrease in heat loss and an increase in thermal resistance. ...

2021 9th International Renewable and Sustainable Energy Conference (IRSEC), Nov 23, 2021

Journal of Thermal Science and Engineering Applications, 2022

In the present work, experimental and numerical studies are conducted to identify and improve the... more In the present work, experimental and numerical studies are conducted to identify and improve the thermal properties of the most commonly used hollow concrete blocks in Morocco. The experimental approach consists in characterizing the thermal conductivity and thermal capacity of the basic materials using the guarded hot plate and the differential calorimeter, respectively. The obtained properties have been exploited as input data in the numerical approach in order to investigate the coupled heat transfers through the honeycomb blocks using the approximation calculation method suggested by EN ISO 6946, and the three-dimensional numerical simulations using the commercial software Ansys Fluent. The obtained results showed that the average differences between the 1D and 3D calculations are less than 7.5% concerning the five type studies. In addition, the increase in the width and number of cavities leads to gain a significant decrease in heat loss and an increase in thermal resistance. ...

2016 3rd International Conference on Renewable Energies for Developing Countries (REDEC), 2016

Considering the importance of reducing energy consumption in the Moroccan building sector, this w... more Considering the importance of reducing energy consumption in the Moroccan building sector, this work deals with a preliminary analysis of the typology and the evolution of the final energy consumption in this sector. The modes of construction and the evolution of the park for different types of housing were also considered. The purpose is also to highlight the potential of the thermal insulation demand.

2014 International Renewable and Sustainable Energy Conference (IRSEC), 2014

Morocco currently witnesses an important economic and social development, accompanied in parallel... more Morocco currently witnesses an important economic and social development, accompanied in parallel to an exponential energy demand which increases the bill of the state, since 95% of the energy is imported from abroad. It also gives a high priority to the development of renewable energies including biogas, given its important deposit and its environmental, economic and social interest. With its energy potential, biogas may figure more prominently in the energy equation, if the optimization of the anaerobic digestion process improves more. To contribute to the improvement of this process, the objective adopted by the present work is to study the effect of different temperatures belonging to the mesophile plan on the performance of production of biogas as well as its content in methane and carbon dioxide. With this aim in mind, a digester with a capacity of 14 liters has been used, equipped with an integrated control device. The digestion temperatures were set at 35, 37 and 40°C, with a time of stay of 21 days. For all experiments, the size of the particles of municipal solid waste has been reduced to 10 mm. The obtained results show a high correlation between the temperature, the production of biogas and the content of methane, with an improvement of the quantity and the quality of biogas of the product registered for a temperature of digestion of 40 °C.