In order to study the thermal performance of a solar cooker used for food cooking, we conducted a... more In order to study the thermal performance of a solar cooker used for food cooking, we conducted an experimental and numerical study to examine the temperature distribution and profiles of a prototype of box type solar cooker realized by the small thermodynamic power plants of Applied Research Unit in Renewable Energies (URAER, GhardaÏa). The numerical simulation takes into account the initial conditions, the weather conditions and the boundary conditions. The water temperature values in the pot and on the absorber plate were obtained by the Comsol software. The experimental tests (stagnation and sensible heating tests) were carried out under the climatic conditions of the GhardaÏa city (located at a latitude $of 32.39 ^{\\circ}$, a longitude $of 3.78 ^{\\circ}$ and an altitude of 463m at sea level). The tests were carried out on a clear days in a summer month under global solar radiation received on a horizontal surface varying between 800 and $1000\\text{W}/ \\text{m}^{2}$ and an ambient temperature varying from 28 $to 30 ^{\\circ}\\text{C}$. The experimental results and those of the simulation are compared and analyzed.
The size of parabolic trough concentrators limits the mechanical sun tracking system’s solution. ... more The size of parabolic trough concentrators limits the mechanical sun tracking system’s solution. Generally, concentrating collectors use only one-axis or two-axis sun tracking; the sun’s position changes hourly; hence, the solar collector should be continuously adjusted in order to produce the maximum power. Single-axis tracking systems are considerably cheaper and easier to construct, but their efficiency is lower than that of the two-axis tracking systems. In this paper, we present a study that confirms the feasibility of a novel one-axis sun tracking system with reflector displacement in order to minimize the optical losses caused by the cosine effect in the small parabolic trough concentrators. Optical and thermal simulations are performed to prove the efficiency of the novel system by comparison between the two cases, with reflector displacement and the ordinary system—the results are very interesting. We have proposed a novel sun tracking system with a good annual efficiency.
L’objectif principal est de trouver un système de régulation capable de gérer le transfert d’éner... more L’objectif principal est de trouver un système de régulation capable de gérer le transfert d’énergie électrique dans le générateur photovoltaïque et de contrôler le fonctionnement de l’installation en question. Dans le cadre de ce travail, on a commencé par adopter une méthode de dimensionnement pour les installations photovoltaïques, puis on a élaboré un logiciel informatique permettant la gestion du système après avoir analyser les différentes stratégies de régulation. Finalement, des mesures ont été prises, suite à une simulation du système; pour connaître le fonctionnement de la centrale avec la méthode de régulation adoptée.
Après une simulation de la répartition des rayons solaires incidents sur l’absorbeur d’un cuiseur... more Après une simulation de la répartition des rayons solaires incidents sur l’absorbeur d’un cuiseur type boîte à surface inclinée en milieux arides durant l’année, on présentera, dans cet article, le premier cuiseur solaire réalisé à l’Unité de Recherche Appliquée en Energies Renouvelables, ce dernier est équipé d’un réflecteur à concentration pour permettre de collecter un maximum d’énergie. Une conception mécanique, ainsi qu’une simulation optique du cuiseur durant le mois du test sont nécessaires. Les tests ont été effectués sous ensoleillement direct de Ghardaïa (Latitude 32.48°N) durant le mois d’Avril. Différents thermocouples ont été implantés sur divers endroits du cuiseur, les mesures de températures issues de ces capteurs ont été prélevées chaque une minute de temps. Le test présenté dans cet article concerne la préparation d’un café presse pendant deux moments différents de la journée. La température de l’absorbeur avait dépassée les 100 °C, ce qui a permis la préparation d...
In this paper, we present an optical simulation of concentrating solar tower system using differe... more In this paper, we present an optical simulation of concentrating solar tower system using different forms of cavity receiver. Mathematical model used to find the position of the sun, angle of incidence, position of the reflected ray and orientation of heliostats is developed in MATLAB. For each heliostat, the angle of incidence is included in the calculation of the reflected radiation. Optical simulation was performed employing TracePro ray tracing software using Monte Carlo ray tracing method to get the concentrated solar ray distribution in the cavity receiver. The aim of the work is to seek the geometry that gives the best distribution of concentrated rays, with the best efficiency.
ABSTRACT In the current study, we present the optical efficiency of six different shapes of cavit... more ABSTRACT In the current study, we present the optical efficiency of six different shapes of cavity receivers that are mostly used in solar power tower systems. This study was conducted in applied research unit for renewable energies (URAER) at Ghardaïa province, Algeria. Each heliostat reflects the sunray into the centre point of the cavity aperture situated at 7.4 m on the top tower. In order to find the orientation of each heliostat, several parameters relating the position of the sun and heliostat tower system are estimated. Optical simulation was performed by means of TracePro® 2013 ray tracing software using the MCRT (Monte Carlo ray trace) method. The results show that conical and trapezoidal shapes perform better than other studied cavities. They mostly exhibit the highest optical efficiency reaching 92.65%, 91.81% at absorptivity 85% and an optical efficiency of 90.88% and 89.30% at absorptivity 75%.
13th SGEM GeoConference on ENERGY AND CLEAN TECHNOLOGIES, 2013
ABSTRACT In this work we present a design of a mathematical model used in the simulation of the b... more ABSTRACT In this work we present a design of a mathematical model used in the simulation of the behavior of a heliostats- tower optical system. The model permits the calculation of the orientation angles of a heliostat (two axes tracking system) in a solar tower system, it also allows to calculate the shading area of a heliostat on another. The reflected radiation to the target (the tower) is calculated from the incident radiation from the sun and calculated shaded area. For each heliostat, the cosine effect (angle of incidence) is included in the calculation of the reflected radiation, and then, the shadow effect is taken into account on reducing the radiation reflected by an amount which depends on the shadow area
4th International Conference on Power Engineering, Energy and Electrical Drives, 2013
ABSTRACT In this work the heat transfer of a spiral tube receiver exposed to concentrated solar r... more ABSTRACT In this work the heat transfer of a spiral tube receiver exposed to concentrated solar radiation is studied theoretically. The simulations were performed using Fluent6.3.26 for two different sections at several Reynolds numbers: 100, 300, 500, 700, and 1000 to see the effect of the inlet velocity on the outlet temperature. The effect of the inlet temperature is also discussed by varying the inlet temperature of the water of 293K to 313K. The results show that the average temperature of the heating and adiabatic surface (inner wall) is decreasing when the velocity inlet is increasing. The outlet temperature of a semicircular section is higher than that of the circular section, but the Nusselt number of this one is twice higher as that of semicircular section and it's due to the geometrical shape of the section.
In order to study the thermal performance of a solar cooker used for food cooking, we conducted a... more In order to study the thermal performance of a solar cooker used for food cooking, we conducted an experimental and numerical study to examine the temperature distribution and profiles of a prototype of box type solar cooker realized by the small thermodynamic power plants of Applied Research Unit in Renewable Energies (URAER, GhardaÏa). The numerical simulation takes into account the initial conditions, the weather conditions and the boundary conditions. The water temperature values in the pot and on the absorber plate were obtained by the Comsol software. The experimental tests (stagnation and sensible heating tests) were carried out under the climatic conditions of the GhardaÏa city (located at a latitude $of 32.39 ^{\\circ}$, a longitude $of 3.78 ^{\\circ}$ and an altitude of 463m at sea level). The tests were carried out on a clear days in a summer month under global solar radiation received on a horizontal surface varying between 800 and $1000\\text{W}/ \\text{m}^{2}$ and an ambient temperature varying from 28 $to 30 ^{\\circ}\\text{C}$. The experimental results and those of the simulation are compared and analyzed.
The size of parabolic trough concentrators limits the mechanical sun tracking system’s solution. ... more The size of parabolic trough concentrators limits the mechanical sun tracking system’s solution. Generally, concentrating collectors use only one-axis or two-axis sun tracking; the sun’s position changes hourly; hence, the solar collector should be continuously adjusted in order to produce the maximum power. Single-axis tracking systems are considerably cheaper and easier to construct, but their efficiency is lower than that of the two-axis tracking systems. In this paper, we present a study that confirms the feasibility of a novel one-axis sun tracking system with reflector displacement in order to minimize the optical losses caused by the cosine effect in the small parabolic trough concentrators. Optical and thermal simulations are performed to prove the efficiency of the novel system by comparison between the two cases, with reflector displacement and the ordinary system—the results are very interesting. We have proposed a novel sun tracking system with a good annual efficiency.
L’objectif principal est de trouver un système de régulation capable de gérer le transfert d’éner... more L’objectif principal est de trouver un système de régulation capable de gérer le transfert d’énergie électrique dans le générateur photovoltaïque et de contrôler le fonctionnement de l’installation en question. Dans le cadre de ce travail, on a commencé par adopter une méthode de dimensionnement pour les installations photovoltaïques, puis on a élaboré un logiciel informatique permettant la gestion du système après avoir analyser les différentes stratégies de régulation. Finalement, des mesures ont été prises, suite à une simulation du système; pour connaître le fonctionnement de la centrale avec la méthode de régulation adoptée.
Après une simulation de la répartition des rayons solaires incidents sur l’absorbeur d’un cuiseur... more Après une simulation de la répartition des rayons solaires incidents sur l’absorbeur d’un cuiseur type boîte à surface inclinée en milieux arides durant l’année, on présentera, dans cet article, le premier cuiseur solaire réalisé à l’Unité de Recherche Appliquée en Energies Renouvelables, ce dernier est équipé d’un réflecteur à concentration pour permettre de collecter un maximum d’énergie. Une conception mécanique, ainsi qu’une simulation optique du cuiseur durant le mois du test sont nécessaires. Les tests ont été effectués sous ensoleillement direct de Ghardaïa (Latitude 32.48°N) durant le mois d’Avril. Différents thermocouples ont été implantés sur divers endroits du cuiseur, les mesures de températures issues de ces capteurs ont été prélevées chaque une minute de temps. Le test présenté dans cet article concerne la préparation d’un café presse pendant deux moments différents de la journée. La température de l’absorbeur avait dépassée les 100 °C, ce qui a permis la préparation d...
In this paper, we present an optical simulation of concentrating solar tower system using differe... more In this paper, we present an optical simulation of concentrating solar tower system using different forms of cavity receiver. Mathematical model used to find the position of the sun, angle of incidence, position of the reflected ray and orientation of heliostats is developed in MATLAB. For each heliostat, the angle of incidence is included in the calculation of the reflected radiation. Optical simulation was performed employing TracePro ray tracing software using Monte Carlo ray tracing method to get the concentrated solar ray distribution in the cavity receiver. The aim of the work is to seek the geometry that gives the best distribution of concentrated rays, with the best efficiency.
ABSTRACT In the current study, we present the optical efficiency of six different shapes of cavit... more ABSTRACT In the current study, we present the optical efficiency of six different shapes of cavity receivers that are mostly used in solar power tower systems. This study was conducted in applied research unit for renewable energies (URAER) at Ghardaïa province, Algeria. Each heliostat reflects the sunray into the centre point of the cavity aperture situated at 7.4 m on the top tower. In order to find the orientation of each heliostat, several parameters relating the position of the sun and heliostat tower system are estimated. Optical simulation was performed by means of TracePro® 2013 ray tracing software using the MCRT (Monte Carlo ray trace) method. The results show that conical and trapezoidal shapes perform better than other studied cavities. They mostly exhibit the highest optical efficiency reaching 92.65%, 91.81% at absorptivity 85% and an optical efficiency of 90.88% and 89.30% at absorptivity 75%.
13th SGEM GeoConference on ENERGY AND CLEAN TECHNOLOGIES, 2013
ABSTRACT In this work we present a design of a mathematical model used in the simulation of the b... more ABSTRACT In this work we present a design of a mathematical model used in the simulation of the behavior of a heliostats- tower optical system. The model permits the calculation of the orientation angles of a heliostat (two axes tracking system) in a solar tower system, it also allows to calculate the shading area of a heliostat on another. The reflected radiation to the target (the tower) is calculated from the incident radiation from the sun and calculated shaded area. For each heliostat, the cosine effect (angle of incidence) is included in the calculation of the reflected radiation, and then, the shadow effect is taken into account on reducing the radiation reflected by an amount which depends on the shadow area
4th International Conference on Power Engineering, Energy and Electrical Drives, 2013
ABSTRACT In this work the heat transfer of a spiral tube receiver exposed to concentrated solar r... more ABSTRACT In this work the heat transfer of a spiral tube receiver exposed to concentrated solar radiation is studied theoretically. The simulations were performed using Fluent6.3.26 for two different sections at several Reynolds numbers: 100, 300, 500, 700, and 1000 to see the effect of the inlet velocity on the outlet temperature. The effect of the inlet temperature is also discussed by varying the inlet temperature of the water of 293K to 313K. The results show that the average temperature of the heating and adiabatic surface (inner wall) is decreasing when the velocity inlet is increasing. The outlet temperature of a semicircular section is higher than that of the circular section, but the Nusselt number of this one is twice higher as that of semicircular section and it's due to the geometrical shape of the section.
Uploads
Papers by Amor Gama