Mohamed Eltawil | Kafrelsheikh University (original) (raw)

Papers by Mohamed Eltawil

Solar Energy, Jun 1, 2021

Abstract The traditional method (TM) of dates syrup (dibs) extraction takes long extraction perio... more Abstract The traditional method (TM) of dates syrup (dibs) extraction takes long extraction period and has poor productivity. The TM depends on putting heavyweights above the heap of dates at room temperature, and wait until dibs extraction. This study aims to design two innovative solar electro-thermal energy systems with hydraulic pressure to extract dates syrup. The electro-thermal systems were used to heat and circulate dates dibs extraction medium, while hydraulic pressure (6 ± 1 and 7 ± 1 bar) was used to squeeze dates instead of traditional weights. Solar water bath (SWB) and solar air bath with rocks storage bed (SABWRSB) were used to catalyst the extraction process. The syrup dibs quality and quantity from different methods were evaluated. For innovative methods, the dates temperature inside the extraction tank was about 49–54 °C. The efficiency of the SWB and SABWRSB for syrup extraction was 48.87% and 13.16%, respectively. Using SWB saved time about 38%, and increased the productivity by 28.75% and 36.66% at a pressure of 6 ± 1 and 7 ± 1 bar, respectively, compared to TM. Heating with SWB increased the productivity by 3.6% and 5.68% compared to SABWRSB at 6 ± 1 and 7 ± 1 bar, respectively. The SWB is recommended for providing the appropriate environment for the dates dibs extraction.

Egyptian Journal of Agricultural Research, Jun 20, 2014

Sugar cane is a labor intensive crop, where the most of the cane operations are carried out manua... more Sugar cane is a labor intensive crop, where the most of the cane operations are carried out manually and the use of machinery is limited only for land preparation. The present study aims to manufacture a new prototype machine for transplanting sugar cane crop. Electronic circuit and servo motor control the movement and orientation of carriage belt of transplanting, whenever the infrared rays control the movement of seedling and determine their positions of transplanting tray. Timeliness of opening and closing has been adjusted by precisely by electronic air valves. The experimental work was carried out at Etay Elbaroud Agricultural Research Station, Behera Governorate. Performance of the machine was evaluated under four forward speeds (0.6, 0.9, 1.2and 1.5 km/h) and three seedling spaces (27, 37and 47 cm). The results indicated evaluated that the highest value of longitudinal scattering and transverse scattering were 4.1 and 3.7 cm at forward speed of 1.5 km/h. While the highest value of energy consumption and transplanting efficiency were 26.49 kW.h/fed and 94.1% at forward speed of 0.6 km/h. On the other hand, missing, floating and dead seedlings increased as forward speed and seedlings spacing increased. The highest values of missing, floating and dead seedlings were 3.8, 3.5 and 3.7% at forward speed of 1.5 km/h and at seedling space 47 cm.

Refrigerated storage, which is believed to be best method for storing the fruits and vegetables i... more Refrigerated storage, which is believed to be best method for storing the fruits and vegetables in fresh form, is not available in rural or remote locations where grid electricity is almost not available. So, without having a conventional energy source at these areas, the present study was taken up to design and fabricate a solar PV powered vapour compression refrigeration system to attain favourable conditions for potato storage, and to evaluate its shelf life under different operating conditions. The system is designed and fabricated in the division of Agril. Engineering at IARI, New Delhi. It consisted of PV panel, lead-acid battery, inverter and the vapour compression refrigeration system consists of a drier-cum-filter besides the main components: compressor, condenser, expansion device, evaporator, exhaust and evaporator fans. The 2.50 m3 cold storage structure was constructed and insulated with proper materials. An evaporatively cooled storage structure (1.0 m3) was used for c...

The present study aims to develop a co-fermentation process using animal manure and organic by-pr... more The present study aims to develop a co-fermentation process using animal manure and organic by-products. The fermentation materials used were: swine manure only as a control, swine manure mixed with corn silage, and swine manure mixed with kitchen wastes. Two concentrations of total solid materials of 5 and 10% were used. The digested materials were analyzed before and after the experiments and the biogas generation was evaluated in terms of CH4. The system is evaluated under continuous feeding with mesophilic temperature. Results indicated that increasing the total solid matter from 5% to 10% leads to increase the biogas generation from 0.389 to 0.556 L/L-d for swine manure only. Using the higher TS of 10% produced biogas of about 1.43 times more than that of low TS (5%). Mixing with the corn silage, the test has shown a gas production of 1.11 L/L-d for the level of TS 10%. It was two times more than that of the control. The test with kitchen waste has a biogas production of 1.01 L...

Environmental Science and Pollution Research, 2020

This work aimed to explore a new technique for improving the performance of solar stills (SSs) th... more This work aimed to explore a new technique for improving the performance of solar stills (SSs) through utilizing three different types of a new hybrid structure of heat localization materials (HSHLM) floating on the water surface to increase the evaporation rate as well as water production and minimize heat losses. The three types were exfoliated graphite flakes with wick (type A), carbon foam with wick (type B), and exfoliated graphite flakes with wick and carbon foam (type C). These hybrid structures had good features such as high absorption and hydrophilic capillary forces to interconnected pores for fluid flow through the structure. Two identical SSs were designed, fabricated, and investigated to assess SSs' performance with and without HSHLM (modified and conventional SSs). The obtained results showed that the daily productivity was enhanced by 34.5, 28.6, and 51.8% for type A, type B, and type C, respectively, relative to the conventional one. Moreover, the efficiency of the SS reached about 37.6% for type C; while, it reached about 27% for the conventional SS. Contrary to conventional SSs, the use of HSHLM resulted in increasing the productivity proportional to water depth.

Internet of Things - New Insights [Working Title]

Date palm cultivation is an essential part of Saudi Arabia’s economy. However, it faces several c... more Date palm cultivation is an essential part of Saudi Arabia’s economy. However, it faces several challenges: water scarcity, improper farm management, pests and diseases, inadequate farming practices, processing and marketing, and labor shortages. Artificial intelligence (AI) and the Internet of Things (IoT) can help enrich crop management, enable predictive analytics, increase efficiency, and promote sustainability in date palm cultivation. Recently, interest in this sector has begun by applying the latest precision engineering technologies integrated with AI and IoT techniques to address these challenges. This chapter aims to provide an overview of the applications of AI and IoT-based technologies, such as sensors, ML algorithms, and data analytics, and their potential benefits and challenges in supporting date palm cultivation in Saudi Arabia. Specifically, the applications of AI and IoT in smart precision irrigation, smart systems, cold storage management, pest infestation predic...

Sustainability

Display refrigerators consume significantly high energy, and improving their efficiency is essent... more Display refrigerators consume significantly high energy, and improving their efficiency is essential to minimize energy consumption and greenhouse gas emissions. Therefore, providing the refrigeration system with a reliable and energy-efficient mechanism is a real challenge. This study aims to design and evaluate an intelligent control system (ICS) using artificial neural networks (ANN) for the performance optimization of solar-powered display refrigerators (SPDRs). The SPDR was operated using the traditional control system at a fixed frequency of 60 Hz and then operated based on variable frequencies ranging from 40 to 60 Hz using the designed ANN-based ICS combined with a variable speed drive. A stand-alone PV system provided the refrigerator with the required energy at the two control options. For the performance evaluation, the operating conditions of the SPDR after the modification of its control system were compared with its performance with a traditional control system (TCS) a...

Environmental Science and Pollution Research, 2020

This research aims to investigate the effect of integrating a simple solar collector, floatable b... more This research aims to investigate the effect of integrating a simple solar collector, floatable black wicks, and orientation as modified double-slope solar still (MDSSS), and to compare its performance with conventional double-slope solar still (CDSSS). Costs of the developed desalination system were estimated, and its performance was compared with the previous literatures. A black hose was coiled and used as simple solar collector for preheating the saline water that is fed to the solar still. The floatable black wicks were used to increase the evaporation surface area and cause a localization of absorbed insolation at the evaporation surface of saline water. The longitudinal axis of solar still was oriented to north-south and east-west, the and productivity from each side was quantified. The northern side of MDSSS has more yield than the southern side by 33.98% for the east-west orientation and preheating. For the east-west orientation, preheating, and floatable black wicks, the total yield of MDSSS exceeded the CDSSS by 45.65%. And at the same conditions, the daily average efficiency of southern and northern sides of MDSSS was 25.33 and 37.25%, while for CDSSS, it was 13.87 and 30.73%, respectively. Estimated costs revealed that cost per liter water was about 0.062 and 0.059 $ for CDSSS and MDSSS, respectively. Solar still can provide a reasonable amount of water for irrigation based on daily production by installing the MDSSS in furrow, but keeping the longitudinal axis to east-west can secure more amount of water. The used modifications improved the solar still productivity and efficiency.

Renewable and Sustainable Energy Reviews, 2022

Misr Journal of Agricultural Engineering, 2009

Misr Journal of Agricultural Engineering, 2011

Energy Conversion and Management, 2016

Abstract This paper offers a hybrid solar desalination system comprising a humidification-dehumid... more Abstract This paper offers a hybrid solar desalination system comprising a humidification-dehumidification and four solar stills. The developed hybrid desalination system reuses the drain warm water from humidification-dehumidification to feed solar stills to stop the massive warm water loss during desalination. Reusing the drain warm water increases the gain output ratio of the system by 50% and also increased the efficiency of single solar still to about 90%. Furthermore, the production of a single solar still as a part of the hybrid system was more than that of the conventional one by approximately 200%. The daily water production of the conventional one, single solar still, four solar still, humidification- dehumidification and hybrid system were 3.2, 10.5, 42, 24.3 and 66.3 kg/day, respectively. Furthermore, the cost per unit liter of distillate from conventional one, humidification- dehumidification and hybrid system were around 0.049,0.049, 0.049,0.058 and $0.034, respectively.

2008 Twenty-Third Annual IEEE Applied Power Electronics Conference and Exposition, 2008

ABSTRACT In this paper an optimum design and control of three-phase grid-connected PV system has ... more ABSTRACT In this paper an optimum design and control of three-phase grid-connected PV system has been proposed and analyzed. Also, a developed maximum power point tracking (MPPT) controller that uses the PV array differential power to voltage (dP/dV) as an index to provide the reference voltage of maximum power point (MPP) quickly and accurately is presented. The control scheme of a three phase current-controlled space vector pulse-width modulation (SVPWM) inverter in rotating synchronous coordinate d-q with the proposed MPPT algorithm and feed-forward compensation is discussed. The PV grid-connected system controller employs multi-loop control with the filter inductor current of the inverter in the inner loop to achieve fast dynamic response and the outer loop to control dc bus voltage for MPPT. The design method provided in the paper for the controller parameters and filter proved to be very practical and effective. Both the power quality into the grid and power factor correction comply with standards IEEE 929-2000. Good agreement is obtained between simulation and experimental results which illustrated the high performance of the proposed approach.

The existence of a mixed mode (direct and indirect) multi-tray crop drying system connected to ph... more The existence of a mixed mode (direct and indirect) multi-tray crop drying system connected to photovoltaic panels could present a possible solution for horticultural produce preservation and increasing of its shelf life. This study aim to design, fabricate and test of a mixed mode multi-tray crop drying system operated by solar photovoltaic (SPV). A fig fruits (Ficus carica) was dried to evaluate the system performance. A comparison between mixed mode forced dehydration with three airflow rates (1.52, 2.15 and 3.25 m 3 /min), natural convection drying (direct and indirect) and electrical oven drying with different figs treatment (1% sodium hydroxide and 1.5% aqueous solution of sodium metabisulfit then drying; 1.5% aqueous solution of sodium metabisulfit then drying-blanching-drying and 70% sugar solution) was conducted. Results indicated that, the average daily PV panel energy output of 1.28 kWh/d was oversized the daily load energy demand by 50.4, 44.3 and 39.61% (where load energy were 0.635, 0.713 and 0.773 kWh/d) for different airflow rates of 1.52, 2.15, 3.25 m 3 /min, respectively. The average daily conversion efficiency of SPV was 8.76% corresponding to average daily panel temperature of 47.55 oC. The best pretreatment for drying figs was with 1.5% aqueous solution of sodium metabisulfit. Dehydration of figs treated with 1.5% sodium metabisulfit by electrical oven required of about 20 hrs, while dehydration by the mixed mode multi-tray crop drying system powered by SPV required of about 38, 33 and 27 hrs spread over three drying sunny days at airflow rates of 1.52, 2.15 and 3.25 m 3 /min, respectively. The mixed mode direct natural convection required of

Renewable and Sustainable Energy Reviews, 2013

ABSTRACT The photovoltaic (PV) system is one of the renewable energies that attract the attention... more ABSTRACT The photovoltaic (PV) system is one of the renewable energies that attract the attention of researchers in the recent decades. The PV generators exhibit nonlinear I-V and P-V characteristics. The maximum power produced varies with both irradiance and temperature. Since the conversion efficiency of PV arrays is very low, it requires maximum power point tracking (MPPT) control techniques. The maximum power point tracking (MPPT) is the automatic control algorithm to adjust the power interfaces and achieve the greatest possible power harvest, during moment to moment variations of light level, shading, temperature, and photovoltaic module characteristics. The purpose of the MPPT is to adjust the solar operating voltage close to the MPP under changing atmospheric conditions. It has become an essential component to evaluate the design performance of PV power systems. This investigation aims to assess different MPPT techniques, provide background knowledge, implementation topology, grid interconnection of PV and solar microinverter requirements presented in the literature, doing depth comparisons between them with a brief discussion. The MPPT merits, demerits and classification, which can be used as a reference for future research related to optimizing the solar power generation, are also discussed. Conventional methods are easy to implement but they suffer from oscillations at MPP and tracking speed is less due to fixed perturb step. Intelligent methods are efficient; oscillations are lesser at MPP in steady state and tracked quickly in comparison to conventional methods.

Solar Energy, Jun 1, 2021

Abstract The traditional method (TM) of dates syrup (dibs) extraction takes long extraction perio... more Abstract The traditional method (TM) of dates syrup (dibs) extraction takes long extraction period and has poor productivity. The TM depends on putting heavyweights above the heap of dates at room temperature, and wait until dibs extraction. This study aims to design two innovative solar electro-thermal energy systems with hydraulic pressure to extract dates syrup. The electro-thermal systems were used to heat and circulate dates dibs extraction medium, while hydraulic pressure (6 ± 1 and 7 ± 1 bar) was used to squeeze dates instead of traditional weights. Solar water bath (SWB) and solar air bath with rocks storage bed (SABWRSB) were used to catalyst the extraction process. The syrup dibs quality and quantity from different methods were evaluated. For innovative methods, the dates temperature inside the extraction tank was about 49–54 °C. The efficiency of the SWB and SABWRSB for syrup extraction was 48.87% and 13.16%, respectively. Using SWB saved time about 38%, and increased the productivity by 28.75% and 36.66% at a pressure of 6 ± 1 and 7 ± 1 bar, respectively, compared to TM. Heating with SWB increased the productivity by 3.6% and 5.68% compared to SABWRSB at 6 ± 1 and 7 ± 1 bar, respectively. The SWB is recommended for providing the appropriate environment for the dates dibs extraction.

Egyptian Journal of Agricultural Research, Jun 20, 2014

Sugar cane is a labor intensive crop, where the most of the cane operations are carried out manua... more Sugar cane is a labor intensive crop, where the most of the cane operations are carried out manually and the use of machinery is limited only for land preparation. The present study aims to manufacture a new prototype machine for transplanting sugar cane crop. Electronic circuit and servo motor control the movement and orientation of carriage belt of transplanting, whenever the infrared rays control the movement of seedling and determine their positions of transplanting tray. Timeliness of opening and closing has been adjusted by precisely by electronic air valves. The experimental work was carried out at Etay Elbaroud Agricultural Research Station, Behera Governorate. Performance of the machine was evaluated under four forward speeds (0.6, 0.9, 1.2and 1.5 km/h) and three seedling spaces (27, 37and 47 cm). The results indicated evaluated that the highest value of longitudinal scattering and transverse scattering were 4.1 and 3.7 cm at forward speed of 1.5 km/h. While the highest value of energy consumption and transplanting efficiency were 26.49 kW.h/fed and 94.1% at forward speed of 0.6 km/h. On the other hand, missing, floating and dead seedlings increased as forward speed and seedlings spacing increased. The highest values of missing, floating and dead seedlings were 3.8, 3.5 and 3.7% at forward speed of 1.5 km/h and at seedling space 47 cm.

Refrigerated storage, which is believed to be best method for storing the fruits and vegetables i... more Refrigerated storage, which is believed to be best method for storing the fruits and vegetables in fresh form, is not available in rural or remote locations where grid electricity is almost not available. So, without having a conventional energy source at these areas, the present study was taken up to design and fabricate a solar PV powered vapour compression refrigeration system to attain favourable conditions for potato storage, and to evaluate its shelf life under different operating conditions. The system is designed and fabricated in the division of Agril. Engineering at IARI, New Delhi. It consisted of PV panel, lead-acid battery, inverter and the vapour compression refrigeration system consists of a drier-cum-filter besides the main components: compressor, condenser, expansion device, evaporator, exhaust and evaporator fans. The 2.50 m3 cold storage structure was constructed and insulated with proper materials. An evaporatively cooled storage structure (1.0 m3) was used for c...

The present study aims to develop a co-fermentation process using animal manure and organic by-pr... more The present study aims to develop a co-fermentation process using animal manure and organic by-products. The fermentation materials used were: swine manure only as a control, swine manure mixed with corn silage, and swine manure mixed with kitchen wastes. Two concentrations of total solid materials of 5 and 10% were used. The digested materials were analyzed before and after the experiments and the biogas generation was evaluated in terms of CH4. The system is evaluated under continuous feeding with mesophilic temperature. Results indicated that increasing the total solid matter from 5% to 10% leads to increase the biogas generation from 0.389 to 0.556 L/L-d for swine manure only. Using the higher TS of 10% produced biogas of about 1.43 times more than that of low TS (5%). Mixing with the corn silage, the test has shown a gas production of 1.11 L/L-d for the level of TS 10%. It was two times more than that of the control. The test with kitchen waste has a biogas production of 1.01 L...

Environmental Science and Pollution Research, 2020

This work aimed to explore a new technique for improving the performance of solar stills (SSs) th... more This work aimed to explore a new technique for improving the performance of solar stills (SSs) through utilizing three different types of a new hybrid structure of heat localization materials (HSHLM) floating on the water surface to increase the evaporation rate as well as water production and minimize heat losses. The three types were exfoliated graphite flakes with wick (type A), carbon foam with wick (type B), and exfoliated graphite flakes with wick and carbon foam (type C). These hybrid structures had good features such as high absorption and hydrophilic capillary forces to interconnected pores for fluid flow through the structure. Two identical SSs were designed, fabricated, and investigated to assess SSs' performance with and without HSHLM (modified and conventional SSs). The obtained results showed that the daily productivity was enhanced by 34.5, 28.6, and 51.8% for type A, type B, and type C, respectively, relative to the conventional one. Moreover, the efficiency of the SS reached about 37.6% for type C; while, it reached about 27% for the conventional SS. Contrary to conventional SSs, the use of HSHLM resulted in increasing the productivity proportional to water depth.

Internet of Things - New Insights [Working Title]

Date palm cultivation is an essential part of Saudi Arabia’s economy. However, it faces several c... more Date palm cultivation is an essential part of Saudi Arabia’s economy. However, it faces several challenges: water scarcity, improper farm management, pests and diseases, inadequate farming practices, processing and marketing, and labor shortages. Artificial intelligence (AI) and the Internet of Things (IoT) can help enrich crop management, enable predictive analytics, increase efficiency, and promote sustainability in date palm cultivation. Recently, interest in this sector has begun by applying the latest precision engineering technologies integrated with AI and IoT techniques to address these challenges. This chapter aims to provide an overview of the applications of AI and IoT-based technologies, such as sensors, ML algorithms, and data analytics, and their potential benefits and challenges in supporting date palm cultivation in Saudi Arabia. Specifically, the applications of AI and IoT in smart precision irrigation, smart systems, cold storage management, pest infestation predic...

Sustainability

Display refrigerators consume significantly high energy, and improving their efficiency is essent... more Display refrigerators consume significantly high energy, and improving their efficiency is essential to minimize energy consumption and greenhouse gas emissions. Therefore, providing the refrigeration system with a reliable and energy-efficient mechanism is a real challenge. This study aims to design and evaluate an intelligent control system (ICS) using artificial neural networks (ANN) for the performance optimization of solar-powered display refrigerators (SPDRs). The SPDR was operated using the traditional control system at a fixed frequency of 60 Hz and then operated based on variable frequencies ranging from 40 to 60 Hz using the designed ANN-based ICS combined with a variable speed drive. A stand-alone PV system provided the refrigerator with the required energy at the two control options. For the performance evaluation, the operating conditions of the SPDR after the modification of its control system were compared with its performance with a traditional control system (TCS) a...

Environmental Science and Pollution Research, 2020

This research aims to investigate the effect of integrating a simple solar collector, floatable b... more This research aims to investigate the effect of integrating a simple solar collector, floatable black wicks, and orientation as modified double-slope solar still (MDSSS), and to compare its performance with conventional double-slope solar still (CDSSS). Costs of the developed desalination system were estimated, and its performance was compared with the previous literatures. A black hose was coiled and used as simple solar collector for preheating the saline water that is fed to the solar still. The floatable black wicks were used to increase the evaporation surface area and cause a localization of absorbed insolation at the evaporation surface of saline water. The longitudinal axis of solar still was oriented to north-south and east-west, the and productivity from each side was quantified. The northern side of MDSSS has more yield than the southern side by 33.98% for the east-west orientation and preheating. For the east-west orientation, preheating, and floatable black wicks, the total yield of MDSSS exceeded the CDSSS by 45.65%. And at the same conditions, the daily average efficiency of southern and northern sides of MDSSS was 25.33 and 37.25%, while for CDSSS, it was 13.87 and 30.73%, respectively. Estimated costs revealed that cost per liter water was about 0.062 and 0.059 $ for CDSSS and MDSSS, respectively. Solar still can provide a reasonable amount of water for irrigation based on daily production by installing the MDSSS in furrow, but keeping the longitudinal axis to east-west can secure more amount of water. The used modifications improved the solar still productivity and efficiency.

Renewable and Sustainable Energy Reviews, 2022

Misr Journal of Agricultural Engineering, 2009

Misr Journal of Agricultural Engineering, 2011

Energy Conversion and Management, 2016

Abstract This paper offers a hybrid solar desalination system comprising a humidification-dehumid... more Abstract This paper offers a hybrid solar desalination system comprising a humidification-dehumidification and four solar stills. The developed hybrid desalination system reuses the drain warm water from humidification-dehumidification to feed solar stills to stop the massive warm water loss during desalination. Reusing the drain warm water increases the gain output ratio of the system by 50% and also increased the efficiency of single solar still to about 90%. Furthermore, the production of a single solar still as a part of the hybrid system was more than that of the conventional one by approximately 200%. The daily water production of the conventional one, single solar still, four solar still, humidification- dehumidification and hybrid system were 3.2, 10.5, 42, 24.3 and 66.3 kg/day, respectively. Furthermore, the cost per unit liter of distillate from conventional one, humidification- dehumidification and hybrid system were around 0.049,0.049, 0.049,0.058 and $0.034, respectively.

2008 Twenty-Third Annual IEEE Applied Power Electronics Conference and Exposition, 2008

ABSTRACT In this paper an optimum design and control of three-phase grid-connected PV system has ... more ABSTRACT In this paper an optimum design and control of three-phase grid-connected PV system has been proposed and analyzed. Also, a developed maximum power point tracking (MPPT) controller that uses the PV array differential power to voltage (dP/dV) as an index to provide the reference voltage of maximum power point (MPP) quickly and accurately is presented. The control scheme of a three phase current-controlled space vector pulse-width modulation (SVPWM) inverter in rotating synchronous coordinate d-q with the proposed MPPT algorithm and feed-forward compensation is discussed. The PV grid-connected system controller employs multi-loop control with the filter inductor current of the inverter in the inner loop to achieve fast dynamic response and the outer loop to control dc bus voltage for MPPT. The design method provided in the paper for the controller parameters and filter proved to be very practical and effective. Both the power quality into the grid and power factor correction comply with standards IEEE 929-2000. Good agreement is obtained between simulation and experimental results which illustrated the high performance of the proposed approach.

The existence of a mixed mode (direct and indirect) multi-tray crop drying system connected to ph... more The existence of a mixed mode (direct and indirect) multi-tray crop drying system connected to photovoltaic panels could present a possible solution for horticultural produce preservation and increasing of its shelf life. This study aim to design, fabricate and test of a mixed mode multi-tray crop drying system operated by solar photovoltaic (SPV). A fig fruits (Ficus carica) was dried to evaluate the system performance. A comparison between mixed mode forced dehydration with three airflow rates (1.52, 2.15 and 3.25 m 3 /min), natural convection drying (direct and indirect) and electrical oven drying with different figs treatment (1% sodium hydroxide and 1.5% aqueous solution of sodium metabisulfit then drying; 1.5% aqueous solution of sodium metabisulfit then drying-blanching-drying and 70% sugar solution) was conducted. Results indicated that, the average daily PV panel energy output of 1.28 kWh/d was oversized the daily load energy demand by 50.4, 44.3 and 39.61% (where load energy were 0.635, 0.713 and 0.773 kWh/d) for different airflow rates of 1.52, 2.15, 3.25 m 3 /min, respectively. The average daily conversion efficiency of SPV was 8.76% corresponding to average daily panel temperature of 47.55 oC. The best pretreatment for drying figs was with 1.5% aqueous solution of sodium metabisulfit. Dehydration of figs treated with 1.5% sodium metabisulfit by electrical oven required of about 20 hrs, while dehydration by the mixed mode multi-tray crop drying system powered by SPV required of about 38, 33 and 27 hrs spread over three drying sunny days at airflow rates of 1.52, 2.15 and 3.25 m 3 /min, respectively. The mixed mode direct natural convection required of

Renewable and Sustainable Energy Reviews, 2013

ABSTRACT The photovoltaic (PV) system is one of the renewable energies that attract the attention... more ABSTRACT The photovoltaic (PV) system is one of the renewable energies that attract the attention of researchers in the recent decades. The PV generators exhibit nonlinear I-V and P-V characteristics. The maximum power produced varies with both irradiance and temperature. Since the conversion efficiency of PV arrays is very low, it requires maximum power point tracking (MPPT) control techniques. The maximum power point tracking (MPPT) is the automatic control algorithm to adjust the power interfaces and achieve the greatest possible power harvest, during moment to moment variations of light level, shading, temperature, and photovoltaic module characteristics. The purpose of the MPPT is to adjust the solar operating voltage close to the MPP under changing atmospheric conditions. It has become an essential component to evaluate the design performance of PV power systems. This investigation aims to assess different MPPT techniques, provide background knowledge, implementation topology, grid interconnection of PV and solar microinverter requirements presented in the literature, doing depth comparisons between them with a brief discussion. The MPPT merits, demerits and classification, which can be used as a reference for future research related to optimizing the solar power generation, are also discussed. Conventional methods are easy to implement but they suffer from oscillations at MPP and tracking speed is less due to fixed perturb step. Intelligent methods are efficient; oscillations are lesser at MPP in steady state and tracked quickly in comparison to conventional methods.