[en] Highlights: • Experimental study of the new solar air heater with latent heat. • Energy analysis of solar air heaters with and without latent storage energy. • The daily energy efficiency of the solar air heater with phase change materials is 33%. - Abstract: In the present work an experimental study is made to enhance the efficiency of a simple fabricated Solar Air Heater (SAH) by using the thermal heat storage. A rectangular cavity filled with a Paraffin wax is used as a latent storage unit. An experimental study of two similar designed solar air collector (with and without Phase Change Material), is carried out to evaluate the PCM unit importance. The results show that during the night the outlet air temperature of the SAH was enhanced with using PCM. The daily energy efficiency of the SAH without PCM reached 17%, while the daily energy efficiency of the SAH with PCM reached 33%.

[en] Highlights: • A new solar air heater collector using a phase change material. • Experimental study of the new solar air heater collector with latent storage. • Energy and exergy analysis of the solar heater with latent storage collector. • Nocturnal use of solar air heater collector. - Abstract: An experimental study was conducted to evaluate the thermal performance of a new solar air heater collector using a packed bed of spherical capsules with a latent heat storage system. Using both first and second law of thermodynamics, the energetic and exegetic daily efficiencies were calculated in Closed/Opened and Opened cycle mode. The solar energy was stored in the packed bed through the diurnal period and extracted at night. The experimentally obtained results are used to analyze the performance of the system, based on temperature distribution in different localization of the collectors. The daily energy efficiency varied between 32% and 45%. While the daily exergy efficiency varied between 13% and 25%

[en] Highlights: • Design and construction of solar heat tube exchanger and water calorimeter. • Exergy and energy efficiency of solar parabolic concentrator. • Analytical and experimental study of solar parabolic concentrator. • Comparative study of different methods of solar concentrated energy measurement. - Abstract: The purpose of this work is to evaluate the energy coming to the focus of a solar parabolic concentrator SPC using four types of absorbers: flat plate, disk, water calorimeter (WC) and solar heat exchanger (SHE), developed in the Research and Technologies Centre of Energy in Borj Cedria in Tunisia (CRTEn). The temperature of the absorber, the solar energy absorbed by the receiver, the mean concentration ratio and both energy and exergy efficiency of the system were obtained experimentally. In order to validate the experimental results of the SHE and to determine the SPC efficiency using the disk, an analytical study based on thermodynamics analysis is carried out. We note that a good agreement between the four experimental methods has been obtained with the four receivers used in this work. The thermal energy efficiency varies from 40% to 77%, the concentrating system reaches an average exergy efficiency of 50% and a concentration factor around 178

[en] Highlights: • Design and construction of solar parabolic concentrator. • Photogrammetry study of SPC. • Slope error and optical efficiency of SPC. • Reflector materials of SPC. • Programmed tracking solar system. - Abstract: Renewable energy generation is becoming more prevalent today. It is relevant to consider that solar concentration technologies contribute to provide a real alternative to the consumption of fossil fuels. The purpose of this work is the characterization of a solar parabolic solar concentrator (SPC) designed, constructed and tested in the Research and Technologies Centre of Energy in Tunisia (CRTEn) in order to improve the performance of the system. Photogrammetry measurement used to analyze the slope errors and to determine hence determining the geometric deformation of the SPC system, which presents an average slope error around 0.0002 and 0.0073 mrad respectively in the center and in the extremities. An optimization of the most performed reflector material has been done by an experimental study of three types of reflectors. A two axes programmed tracking system realized, used and tested in this study. An experimental study is carried out to evaluate the solar parabolic concentrator thermal efficiency after the mechanical and the optical SPC optimization. The thermal energy efficiency varies from 40% to 77%, the concentrating system reaches an average concentration factor around 178

[en] Highlights: • Numerical analysis of a latent heat thermal energy storage. • A solar water heater collector using a phase change material. • Experimental study of solar water heater collector with latent storage. - Abstract: The energy production provided by a heat excess or a discontinuous source (solar radiation, waste heat, etc.) involves the utilization of a thermal storage systems. In this work, an experimental study of a storage system using paraffin as phase change material (PCM) has been done. This system takes the form of two rectangular cavities incorporating behind the absorber of a flat plat solar collector. Measurements were performed during different weather conditions and illustrate that the PCM contributes to increase the performance of the solar collector at night. An analysis of the temperature stratification inside the PCM-filled cavities was also carried out. Theoretical solid–liquid of phase change material model is used to evaluate the PCM melted volume fraction, liquid–solid interfaces, PCM temperature and melting/solidification flow in the PCM-filled cavity used in the present experimental study

[en] Highlights: • Modeling, optimization and control strategy of the agricultural greenhouse. • New dynamic modeling of the greenhouse with a good statistical performance. • A better performance of the developed FLC controller. The agricultural greenhouse presents a complicated procedure since the strong perturbations and the important number of its input parameters, which have a great potential and capacity to influence the climate inside it. For this reason, a Fuzzy Logic Controller (FLC) is developed in order to promote a suitable microclimate by activating the appropriate actuators installed inside the greenhouse with the appropriate rate. The dynamic modeling of the studied greenhouse is presented and simulated under MATLAB/Simulink environment to be experimentally validated within the Research and Technology Center of Energy (CRTEn) in Tunisia. The simulation results illustrate the effectiveness of the proposed dynamic model to investigate the internal air temperature and relative humidity with a low percentage of error. In addition, the developed controller FLC presents an effective solution to get an optimized microclimate indoor the agricultural greenhouse.