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Olive pomace is generated during the production of olive oil. The disposal of olive pomace presents a serious environmental issue to the agricultural community in Morocco. Among all actions devoted to the reduction of olive pomace waste, their revaluation seems to be the most efficient and advantageous from both environmental and economic points of view. Due to its high moisture content, solar drying constitutes an important and promising solution for a possible bio-fuel conversion of olive pomace. For this purpose, a modified uneven-span greenhouse dryer was designed and installed at the faculty of sciences Semlalia, Marrakech, Morocco. An experimental study of solar drying kinetics of the olive pomace was conducted to test the performances of the modified greenhouse dryer under a hybrid (solar/hot air) forced convection mode. The hot-air blower was supplied by electricity from a PV array installed near the greenhouse. The mean temperatures of air within the greenhouse and of the olive waste during the drying hours reached, respectively, 63 °C and 55 °C (from August 3rd to August 5th). The duration of the drying operation of 300 kg of waste from a moisture content of 50 mass% to 19 mass% was 27 h, which was low compared to the open sun drying. Therefore, hybrid forced mode enabled a considerable reduction in drying time, being an aspect to take into account for its use during low solar radiation. The drying kinetics of thin layer two-phase olive pomace was also investigated. The Two-term Gaussian model was found to be the most suitable model to describe the thin layer drying behavior of the two-phase olive pomace dried under hybrid forced convection greenhouse drying mode. In addition, the Fourier series was used to solve the diffusivity equation inside the two-phase olive pomace. The effective diffusivity was found to be 2.0 10–09 m2 s−1 and 2.3 10–09 m2 s−1 using the linear fit and the slope from two successive points methods, respectively. [ABSTRACT FROM AUTHOR]

• The solar radiation intercepted by two commonly used greenhouses, namely the even-span and uneven-span shapes, was optimized under a constant volume for the first time. • The optimal shape and orientation of the greenhouse was determined for drying purposes during the winter period (from 1st October to 31st March) by varying the two decision variables (orientation of the greenhouse and its roof tilt angle) with a small step of 1°. • An extensive energy saving analysis was performed; • The results showed that the uneven–span greenhouse with a roof tilt angle of 45° and an orientation of −80° (10° from the E-W orientation) was optimal for capturing the maximum solar radiation compared to all other configurations, shapes and orientations for Marrakech Morocco. In this work the solar radiation intercepted by two commonly used greenhouses, namely the even-span and uneven-span shapes, was optimized under a constant volume for the first time. The optimal shape and orientation of the greenhouse was determined for drying purposes during the winter period (from 1st October to 31st March) by varying the two decision variables (orientation of the greenhouse and its roof tilt angle) with a small step of 1°. The seasonal solar radiation transmitted inside the greenhouse was computed for each configuration and orientation in order to identify the optimal design and orientation. The solar energy transmitted was evaluated by taking into account the incidence angle dependence of the transmittance of the greenhouse cover (polycarbonate). The results showed that the uneven–span greenhouse with a roof tilt angle of 45° and an orientation of −80° (10° from the E-W orientation) was optimal for capturing the maximum solar radiation compared to all other configurations, shapes and orientations for Marrakech Morocco. This incidence angle dependence of the transmittance did not significantly affect the optimal shape and orientation but reduced the solar radiation inside by 10% compared to the reference case of normal incidence transmittance. It is estimated that the optimum configuration (shape, orientation) will enable to reduce the heating costs of the greenhouse system during the winter season by $ 90 per square meter of the greenhouse floor. This model can be easily extended to assess the total solar radiation intercepted by all such greenhouse systems under different weather conditions. [ABSTRACT FROM AUTHOR]

Solar air collectors are commonly used in a variety of domestic and industrial fields. The simple design and low maintenance cost are among their advantages compared to other solar collectors. However, the main challenge of this type of collector is the low heat transfer coefficient. In this work, the effect of different designs of the absorber plate (waved and V corrugated modification) on the thermal performances, the heat exchange effectiveness and the air outlet temperature of a Double-Pass Parallel-Flow air solar collector was investigated under the solar radiation of MarrakechMorocco in a clear day and for three different mass flows rates (0.008 kg s-1, 0.012 kg s-1 and 0.016 kg s -1). The numerical study was done using Computational Fluid Dynamics (CFD) by the mean of ANSYS Fluent 16.0. The obtained results showed that the V corrugated modification is the most efficient one with efficiency equal to 76.92 % and 87.97 % under the lowest and highest mass flow, respectively. [ABSTRACT FROM AUTHOR]