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Sun drying is the oldest way to preserve but also to valorize and store surplus agricultural production. Nowadays, several types of dryers have been developed, but the solar greenhouse dryer is an ideal solution in our tropical countries because of its implicit and higher load capacity. The greenhouse climate depends on several factors, namely the outdoor climatic conditions (air temperature, wind speed, radiation, etc.) but also on the type of materials used to cover the greenhouse. The study was carried out on a parabolic greenhouse covered by a polyethylene film with a concrete base (absorber) which in turn is placed on the ground and will be tested under the climatic conditions of Dakar, Senegal. It is in this context of sustainable development that this work is carried out. The goal is to determine the distribution of temperatures and wind speeds in the greenhouse. The simulation was carried out using the three-dimensional computer fluid dynamics software (CFD). The turbulence method (k-ε) was used and to solve the radiation transfer equation (RTE) we introduce the discrete ordered method DO. We also add the “Solar Load Model” which gives the position of the sun and its radiations in relation to the layout of the greenhouse according to the date and time of the simulation. The simulation is carried out in a closed greenhouse and the results found can be used to improve the design and control of the greenhouse climate. Air temperatures and velocities simulation give an average of 325.95 K and 0.114 m/s respectively.

This paper is a contribution to the valorization of Typha Australis as building material. The aim of this article is to develop 100% vegetal insulation boards based on powder of typha leaves and gum arabic and starch binders. The comparison of the nature of the binder on the mechanical and thermal properties was carried out. The influence of binder content on the mechanical and thermal insulation properties of panels of typha-gum Arabic and typha-starch was examined too. The density is very small in the case of starch than in the case of gum arabic. The typha-gum arabic panel is 1.17 times more dense than that of typha-starch, for 33.33 % binder. The typha-starch board, for 50 % binder, showed a good compressive strength (1.05 MPa) and is 1.36 times stronger than the typha-gum arabic board. The best thermal conductivity is obtained with the typhastarch board (0.051 W.m-1.K-1) for 33.33 % binder. The thermal conductivity values are close to or lower than many of natural insulating materials. It was also concluded that the typha - gum arabic panels are more effusive. [ABSTRACT FROM AUTHOR]

This work deals with the influence of envelope thickness and solar absorption on the time lag and the decrement factor. For this, a test cell of 1 m3 of volume is built with a material commonly used in construction in Senegal, the compressed earth brick stabilized with cement. The ambient-air temperature inside and outside of test cell and solar direct normal irradiance is measured. The test cell is modeled using EnergyPlus software. The comparison of experimental and theoretical ambient-air temperature puts out a great linear showing the reliability of the model. The time lag and the decrement factor are calculated using the air-sol equivalent temperature of the test cell and the inside ambient-air temperature. The time lag and decrement factor of the compressed stabilized earth brick envelope are respectively 0.22 and 6.6 h showing the good thermal inertia of those bricks. A parametric study is performed to determine the effect of envelope thickness and solar absorptivity on the time lag and decrement factor. The results show that the decrement factor decreases with envelope thickness while the time lag increases linearly and that an envelope thickness of 32 cm has a decrement factor of around zero with a maximum time lag of about 12 h for this type of material. The envelope's solar absorption has a moderate effect on the decrement factor and time lag. [ABSTRACT FROM AUTHOR]