Samir Said - Academia.edu (original) (raw)
Papers by Samir Said
Energy Engineering
Solar energy applications could be the best alternative to the conventional fuels for the purpose... more Solar energy applications could be the best alternative to the conventional fuels for the purposes of domestic, water and space heating and some industries in the sunny, arid, and hot areas. In the present study, the performance of an evacuated tube solar heater for water heating for months of February and March was experimentally investigated. This was performed in a hot and arid area (Nasiriya City, South of Iraq). A solar heater with ten evacuated tube solar collectors with a capacity of 100 liter was used in the experiments. Each evacuated tube had a length of 1.8 m with an outside diameter of 8 cm. It was observed that for the two selected months, water temperature of the solar heater reached a maximum more than 70°C during sunny days with no heat extraction from the tank of the solar heater. Moreover, heat was extracted from the solar collector with four different flowrates 0.5, 0.75, 1, and 1.25 l/min, respectively. The results showed that temperature of the solar heater behaved differently from the static situation. When the heat extraction begun, there was a gradual and noticeable decrease in the water temperature of the heater. The observed decrease was slight with the lowest flowrate (0.25 l/m) and becomes sharp with the highest flowrate (1.25 l/min). However, water temperature of the solar heater remained higher than 40°C for the investigated flowrates except the case of 1.25 l/min. The results showed that evacuated tube solar heater can work efficiently in arid and hot areas in winter and spring seasons when the conditions of solar radiation are suitable.
Solar energy is likely to be the energy of the future; solar ponds, especially salinity gradient ... more Solar energy is likely to be the energy of the future; solar ponds, especially salinity gradient solar ponds (SGSPs), facilitate simple and cost-effective thermal energy storage. Research on maximising their potential is of particular relevance to developing countries, which often have an abundance of solar energy and a critical need for increased power supplies. For this research, a theoretical model for heat transfer in a SGSP was developed to study the energy balance in the three separate zones: the upper convective zone (UCZ), lower convective zone or storage zone (LCZ) and non-convective zone (NCZ). The model showed that the LCZ temperature could reach more than 90 °C in summer and more than 50 °C in winter, in a pond in the Middle East. It was also concluded that surface heat loss occurred mainly by evaporation. The new model was also used to examine the feasibility of a second type of solar pond, the gel pond; this offers solutions to some of the SGSP’s challenges, but presen...
Solar Energy, 2016
Solar energy has a promising future as one of the most important types of renewable energy. Solar... more Solar energy has a promising future as one of the most important types of renewable energy. Solar ponds can be an effective way of capturing and storing this energy. A new theoretical model for a heat transfer in a salinity gradient solar pond has been developed. The model is based on the energy balance for each zone of the pond; three separate zones have been considered, namely the upper convective zone, the lower convective zones, as well as the non-convective zone. The upper and lower zones are considered to be well mixed, which means the temperatures in these zones are uniform. The model shows that the temperature in the storage zone can reach more than 90 °C during the summer season whereas it can be more than 50 °C in winter if the pond is located in the Middle East. In addition, the time dependent temperature for the three layers has been found. Furthermore, it is concluded that heat loss from the pond's surface occurs mainly by evaporation, in comparison to convection and radiation. Heat loss to the ground has been calculated by using three different equations. It was found that the perimeter of the pond has a significant effect on heat loss to the ground from a small pond, while its effect is small in the case of large pond. The validity of the model is tested against experimental data for several established ponds; good agreement is observed. Nomenclature 32 33 Area of the bottom surface of the pond (m) Surface area of the LCZ (m 2) Au Surface area of the UCZ (m 2) Constant (0.36), equation 4 Constant (0.08), equation CCSGSP Closed cycle salt gradient solar pond Humid heat capacity of (kJ/kg K) Thickness of the UCZ (m). Distance of water table from pond's bottom (m) Thickness of water layer (m) Greek letters Emissivity of water Density of the LCZ Density of the UCZ (kg/m 3) Monthly average wind speed in the region of study (m/s) Latent heat of vaporisation (kJ/kg) ℎ Relative humidity Stefen-Boltzmann's constant (5.673x10 −8 W/m 2 K 4)
Applied Thermal Engineering, 2018
The feasibility of the gel solar pond has been investigated. The temperature of the LCZ and t... more The feasibility of the gel solar pond has been investigated. The temperature of the LCZ and the UCZ has been calculated. The cost of the gel pond was calculated and compared with that of the salinity gradient solar pond (SGSP) A gel pond normally costs more than a SGSP. Gel ponds can be seen as a viable alternative to SGSPs only if cheap and environmentally friendly polymers are used.
Solar Energy, 2017
Solar ponds offer an effective way to collect and store incident solar radiation, making them an ... more Solar ponds offer an effective way to collect and store incident solar radiation, making them an attractive alternative to photovoltaic systems for applications which require low-grade heat to operate. If these ponds are to be implemented successfully, then a more complete understanding of the mechanisms and phenomena governing their behaviour is required. Evaporation has been shown previously to be the dominant mode of heat loss from the pond surface, and the fresh water that would need to be added to maintain the pond's inventory could potentially add significantly to operating costs. To this end, an experimental unit was constructed to examine and observe the behaviour of a salinity gradient solar pond (SGSP) before and after covering the pond with a thin layer (0.5 cm) of paraffin, with the aim of eliminating evaporation. The unit was run for 71 days in Nasiriyah, Iraq. This is the first study to attempt to completely eliminate the harmful effects of evaporation on solar pond performance using a liquid layer. The layer successfully eliminated the significant evaporation observed from the uncovered pond and crucially, while the salinity gradient through the nonconvective zone remained substantially intact over the course of the study, the temperature profile became approximately uniform throughout the entire pond after about 50 days. This behaviour has significant implications for the construction of the pond, as it may mean that if evaporation can be largely suppressed, the salinity gradient may not be necessary for the pond to capture and efficiently store heat. Furthermore, the effects on evaporation of different climatic factors such as relative humidity, wind speed, ambient temperature and solar radiation 2 were considered by analysing data measured on-site and longer-term meteorological data. The results showed that ambient temperature, solar radiation and humidity have a significant correlation with the evaporation rate; and their impact varies seasonally. A more comprehensive multiple regression analysis showed that ambient temperature has the highest impact on evaporation, while the effect of the incident solar radiation is insignificant. Such insights are vital in the design and siting of solar ponds, and can be used to minimise evaporative losses.
Chemistry Africa, 2019
1-[(5-Phenyl-1,3, 4-oxadiazol-2-yl)thio] acetone (POTA) was synthesized and tested as a new corro... more 1-[(5-Phenyl-1,3, 4-oxadiazol-2-yl)thio] acetone (POTA) was synthesized and tested as a new corrosion inhibitor for low carbon steel in 1 M hydrochloric acid. The diagnosis of POTA was carried out by FTIR and NMR analysis. Inhibitor performance was investigated using mass loss technique. POTA was acted as a moderate corrosion inhibitor for low carbon steel in 1 M hydrochloric acidic solution with efficiency more than 70%. The inhibitor performance was attributed to the formation of an adsorption layer on the low carbon steel surface. The mechanism of inhibitor adsorption on the low carbon steel surface was according to the Langmuir adsorption isotherm. The value of adsorption heat was within the range of chemical adsorption. Quantum chemical studies were adopted as a theoretical tool to clarify the mechanism of inhibition and to support the experimental part.
Energy Engineering
Solar energy applications could be the best alternative to the conventional fuels for the purpose... more Solar energy applications could be the best alternative to the conventional fuels for the purposes of domestic, water and space heating and some industries in the sunny, arid, and hot areas. In the present study, the performance of an evacuated tube solar heater for water heating for months of February and March was experimentally investigated. This was performed in a hot and arid area (Nasiriya City, South of Iraq). A solar heater with ten evacuated tube solar collectors with a capacity of 100 liter was used in the experiments. Each evacuated tube had a length of 1.8 m with an outside diameter of 8 cm. It was observed that for the two selected months, water temperature of the solar heater reached a maximum more than 70°C during sunny days with no heat extraction from the tank of the solar heater. Moreover, heat was extracted from the solar collector with four different flowrates 0.5, 0.75, 1, and 1.25 l/min, respectively. The results showed that temperature of the solar heater behaved differently from the static situation. When the heat extraction begun, there was a gradual and noticeable decrease in the water temperature of the heater. The observed decrease was slight with the lowest flowrate (0.25 l/m) and becomes sharp with the highest flowrate (1.25 l/min). However, water temperature of the solar heater remained higher than 40°C for the investigated flowrates except the case of 1.25 l/min. The results showed that evacuated tube solar heater can work efficiently in arid and hot areas in winter and spring seasons when the conditions of solar radiation are suitable.
Solar energy is likely to be the energy of the future; solar ponds, especially salinity gradient ... more Solar energy is likely to be the energy of the future; solar ponds, especially salinity gradient solar ponds (SGSPs), facilitate simple and cost-effective thermal energy storage. Research on maximising their potential is of particular relevance to developing countries, which often have an abundance of solar energy and a critical need for increased power supplies. For this research, a theoretical model for heat transfer in a SGSP was developed to study the energy balance in the three separate zones: the upper convective zone (UCZ), lower convective zone or storage zone (LCZ) and non-convective zone (NCZ). The model showed that the LCZ temperature could reach more than 90 °C in summer and more than 50 °C in winter, in a pond in the Middle East. It was also concluded that surface heat loss occurred mainly by evaporation. The new model was also used to examine the feasibility of a second type of solar pond, the gel pond; this offers solutions to some of the SGSP’s challenges, but presen...
Solar Energy, 2016
Solar energy has a promising future as one of the most important types of renewable energy. Solar... more Solar energy has a promising future as one of the most important types of renewable energy. Solar ponds can be an effective way of capturing and storing this energy. A new theoretical model for a heat transfer in a salinity gradient solar pond has been developed. The model is based on the energy balance for each zone of the pond; three separate zones have been considered, namely the upper convective zone, the lower convective zones, as well as the non-convective zone. The upper and lower zones are considered to be well mixed, which means the temperatures in these zones are uniform. The model shows that the temperature in the storage zone can reach more than 90 °C during the summer season whereas it can be more than 50 °C in winter if the pond is located in the Middle East. In addition, the time dependent temperature for the three layers has been found. Furthermore, it is concluded that heat loss from the pond's surface occurs mainly by evaporation, in comparison to convection and radiation. Heat loss to the ground has been calculated by using three different equations. It was found that the perimeter of the pond has a significant effect on heat loss to the ground from a small pond, while its effect is small in the case of large pond. The validity of the model is tested against experimental data for several established ponds; good agreement is observed. Nomenclature 32 33 Area of the bottom surface of the pond (m) Surface area of the LCZ (m 2) Au Surface area of the UCZ (m 2) Constant (0.36), equation 4 Constant (0.08), equation CCSGSP Closed cycle salt gradient solar pond Humid heat capacity of (kJ/kg K) Thickness of the UCZ (m). Distance of water table from pond's bottom (m) Thickness of water layer (m) Greek letters Emissivity of water Density of the LCZ Density of the UCZ (kg/m 3) Monthly average wind speed in the region of study (m/s) Latent heat of vaporisation (kJ/kg) ℎ Relative humidity Stefen-Boltzmann's constant (5.673x10 −8 W/m 2 K 4)
Applied Thermal Engineering, 2018
The feasibility of the gel solar pond has been investigated. The temperature of the LCZ and t... more The feasibility of the gel solar pond has been investigated. The temperature of the LCZ and the UCZ has been calculated. The cost of the gel pond was calculated and compared with that of the salinity gradient solar pond (SGSP) A gel pond normally costs more than a SGSP. Gel ponds can be seen as a viable alternative to SGSPs only if cheap and environmentally friendly polymers are used.
Solar Energy, 2017
Solar ponds offer an effective way to collect and store incident solar radiation, making them an ... more Solar ponds offer an effective way to collect and store incident solar radiation, making them an attractive alternative to photovoltaic systems for applications which require low-grade heat to operate. If these ponds are to be implemented successfully, then a more complete understanding of the mechanisms and phenomena governing their behaviour is required. Evaporation has been shown previously to be the dominant mode of heat loss from the pond surface, and the fresh water that would need to be added to maintain the pond's inventory could potentially add significantly to operating costs. To this end, an experimental unit was constructed to examine and observe the behaviour of a salinity gradient solar pond (SGSP) before and after covering the pond with a thin layer (0.5 cm) of paraffin, with the aim of eliminating evaporation. The unit was run for 71 days in Nasiriyah, Iraq. This is the first study to attempt to completely eliminate the harmful effects of evaporation on solar pond performance using a liquid layer. The layer successfully eliminated the significant evaporation observed from the uncovered pond and crucially, while the salinity gradient through the nonconvective zone remained substantially intact over the course of the study, the temperature profile became approximately uniform throughout the entire pond after about 50 days. This behaviour has significant implications for the construction of the pond, as it may mean that if evaporation can be largely suppressed, the salinity gradient may not be necessary for the pond to capture and efficiently store heat. Furthermore, the effects on evaporation of different climatic factors such as relative humidity, wind speed, ambient temperature and solar radiation 2 were considered by analysing data measured on-site and longer-term meteorological data. The results showed that ambient temperature, solar radiation and humidity have a significant correlation with the evaporation rate; and their impact varies seasonally. A more comprehensive multiple regression analysis showed that ambient temperature has the highest impact on evaporation, while the effect of the incident solar radiation is insignificant. Such insights are vital in the design and siting of solar ponds, and can be used to minimise evaporative losses.
Chemistry Africa, 2019
1-[(5-Phenyl-1,3, 4-oxadiazol-2-yl)thio] acetone (POTA) was synthesized and tested as a new corro... more 1-[(5-Phenyl-1,3, 4-oxadiazol-2-yl)thio] acetone (POTA) was synthesized and tested as a new corrosion inhibitor for low carbon steel in 1 M hydrochloric acid. The diagnosis of POTA was carried out by FTIR and NMR analysis. Inhibitor performance was investigated using mass loss technique. POTA was acted as a moderate corrosion inhibitor for low carbon steel in 1 M hydrochloric acidic solution with efficiency more than 70%. The inhibitor performance was attributed to the formation of an adsorption layer on the low carbon steel surface. The mechanism of inhibitor adsorption on the low carbon steel surface was according to the Langmuir adsorption isotherm. The value of adsorption heat was within the range of chemical adsorption. Quantum chemical studies were adopted as a theoretical tool to clarify the mechanism of inhibition and to support the experimental part.