Riad Benelmir

Physico-chemical properties and thermal stability of microcrystalline cellulose isolated from Alfa fibres.

In this study, microcrystalline cellulose (Alfa-MCC) was extracted from Alfa fibres using acid hydrolysis method. The molecular weight of the cellulose samples was determined by gel permeation chromatography. The crystallinities were studied by means of X-ray diffraction and solid state cross polarization magic angle spinning (13)C nuclear magnetic resonance spectroscopy, revealing that Alfa-MCC was more crystalline than the native cellulose isolated from Alfa fibres. The morphology of the celluloses was investigated using scanning electron microscopy, showing a compact structure and a rough surface. Furthermore, a good thermal stability was shown for Alfa-MCC. Based on these analyses, Alfa-MCC showed tremendous potential use as composites reinforcing agent, foods stabilizer and pharmaceutical additive.

Pseudo-Bond Graph model for the analysis of the thermal behavior of buildings

In this work, a simplified graphical modeling tool, which in some extent can be considered in halfway between detailed physical and data driven dynamic models, has been developed. This model is based on Bond Graphs approach. This approach has the potential to display explicitly the nature of power in a building system, such as a phenomenon of storage, processing, and dissipating energy such as heating, ventilation , and airconditioning systems. This paper represents the developed models of two transient heat conduction problems corresponding to the most practical cases in building envelope, such as the heat transfer through vertical walls, roofs, and slabs. The validation procedure consists of comparing the results obtained with this model with analytical solution. It has shown very good agreement between measured data and Bond Graphs model simulation. The Bond Graphs technique is then used to model the building dynamic thermal behavior over a single zone building structure and compared with a set of experimental data. An evaluation of indoor temperature was carried out in order to check our Bond Graphs model.

Performance Simulation of Two-Bed Adsorption Refrigeration Chiller with Mass Recovery

The technology of adsorption chiller is an efficient way of heat conversion. It can significantly reduce environmental pollution and improve energy efficiency. This paper deals with numerical study of refrigeration systems with silica gel/water pairs with mass recovery. The model is validated with experimental results from the ENERBAT platform. Numerical results are in good agreement with those of experiment. A process of mass recovery is added to study its the effect on the performances of the system. The effect of hot water temperature, cooling water temperature, chilled water temperature and cycle time, on the coefficient of performance (COP), the specific cooling capacity (SCP), the cycled mass, the evaporator outlet temperature and efficiency system are investigated in order to extrapolate the results in the Tunisian climate and to determine their optimum values able to maximize the performance of the system under analysis. The simulation calculation indicates a COP value of 0.7 with a driving source temperature of 85°C in combination with coolant inlet and chilled water inlet temperature of 40°C and 15°C, respectively. The most optimum adsorptiondesorption cycle time is approximately 1240s based on the performance from COP and SCP, achieving a SCP of 400 W/kg.

EFFECT OF THE ADDITION OF GLASS BOTTLE PARTICLES ON THE MECHANICAL STRENGTHS OF COMPRESSED BLOCKS OF FIRED CLAY AND STABILIZED EARTH.

* Gbènondé S. G. MILOHIN 1,2 , Malahimi ANJORIN 1 , Victor S. GBAGUIDI 1 , S. Constant ADISSIN 1 , André DONNOT 2 and Riad BENELMIR 2 . 1. Laboratory of Applied Energetics and Mechanics (LEMA), Polytechnic School of Abomey-Calavi / University of Abomey-Calavi, 01 BP. 2009 Cotonou (Benin). 2. Laboratory of Testing and Research on Wood Material (LERMAB), Faculty of Science & Technology / University of Lorraine –Bd. des Aiguillettes B.P. 70239 F-54506 Vandoeuvre-lès-Nancy cedex, France. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History