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International audience; Adsorption refrigeration technology such as green refrigeration method, following environmental protection and growing economic development, has received much attention. Which are considered more environmentally friendly alternatives to conventional compression refrigeration, since they can use refrigerants that do not contribute to ozone layer depletion and global warming. The silica gel-water is the adsorbent-adsorbate pair used in this paper. Compared with other adsorbents (activated carbonmethanol, Zeolite-water), silica gel-water presents the advantage of excellent physical and thermal properties of water (high latent heat of evaporation, low viscosity, high thermal conductivity , thermal stability in a wide range of operating temperature and a compatibility with several materials) as well as good adsorption property of silica gel (high adsorption/desorption rate and low generation temperature). The couple of silica gel-water can be classified as the best couple for adsorption cooling applications. This paper presents an experimental study of a solar adsorption refrigeration system for three typical days. The variation of the solar flux, the characteristic of temperatures of the solar collector as well as the temperatures of the various components of the adsorption chiller allowed seeing the effect of the solar flux on the various parameters and the performance of the adsorption chiller for two different cases : solar/aerothermal coupling and the solar /geothermal coupling system.

This paper aims to study a numerical model of an adsorption chiller driven with solar energy that is confronted to experimental measurements. This article deals with numerical study of refrigeration systems using a pair of silica gel and water with simulink. The results include the temperature of desorber, the temperature of chilled, cooling and hot water, temperature of two adsorption/desorption beds, condenser and evaporator, the refrigerant saturation pressures in the two compartments and the time variation of water uptake in two adsorbent beds.

The present work proposes a continuous solar adsorption refrigerator for a positive cold storage room of 231 m3 used for fruits and vegetables preservation and installed in the south of Tunisia. After the estimation of the storage room cooling load, which is equal to 13 kW, a parametric study, aims to improve, the performance of the chiller is done in order to achieve the storage room need and to estimate the required heat in the refrigerator generator. A theoretical model, based on the thermodynamics of the adsorption process, heat and mass transfer within the porous medium and energy balance in the system components, is developed and a simulation with Matlab/Simulink, is carried out. The model was established and validated with the literature experimental data. A maximum coefficient of performance of 0.52 and cooling load of 22 kW are reached at cycle time of 800 seconds, the inlet temperatures of heating, cooling and chilled water are 85°C, 22°C and 15°C, respectively.

In this work, a simplified nonlinear coupled model and a simplified linear coupled model are examined in order to determine the model that better approaches the global mass and heat transfers during water vapor absorption by a falling film of LiBr solution in a spiral tubular absorber of an absorption chiller. The linear coupled model gives up analytical expressions that are used to determine overall heat and mass transfer coefficients from the experimental measurements taken at the inlet and outlet of absorber. These coupled overall transfer coefficients are used with the uncoupled ones that are deduced from the LMD method to determine the simulated absorption parameters along the absorber area. The comparison between the two models based essentially on the different parameters values at the inlet and the outlet of the absorber shows that nonlinear model approaches better experimental results. It shows also that the use of overall coupled transfer coefficients is not significant at low solution flow rates usually encountered in absorption chiller application and therefore the use of the overall transfer coefficients extracted from LMD method approaches well experimental data. The nonlinear model which is the approved model points up that the absorbed water vapor quantity and the overall effective mass transfer coefficient for the spiral tubular absorber increase with decreasing cooling water temperatures.

Most of the building materials are considered porous, and composed of solid matrix and pores. In the pores, the moisture can be existed in two phases: liquid and vapor. Thus, the mass balance equation is comprised of various moisture driving potentials that translate the movement of the different existing phases occupying pores and the hygroscopic behavior of a porous construction material. This study suggests to resolve a hygrothermal mathematical model of heat and mass transfers in different porous building materials by a numerical investigation. Thereby, the evolution of temperature and moisture content fields has been processed. So, numerous series of hygrothermal calculation on several cases of wall are exposed. Firstly, a case of monolayer wall of massive wood has been treated. In this part, we have compared the numerical solution of the model on one and two dimensions and the effect of dimensional space has been evaluated. In the second case, three building materials (concrete, wood fiberboard and wooden insulation) are tested separately with the same boundary conditions and their hygrothermal behavior are compared. The evaluation of the exchange of heat and air at the interface between the wall and the interior ambiance is carried., {"references":["J. Zhang, X. Zheng, L. Chen, Y. Sun, Effect of residual oil saturation on hydrodynamic properties of porous media; Journal of hydrology Volume 515, 16 July 2014, Pages 281–291.","L. Fengzhi, L. Yi, L. Yingxi, L. Zhongxuan, Numerical simulation of coupled heat and mass transfer in hygroscopic porous materials considering the influence of atmospheric pressure, Numer. Heat Transfer B 45 (3) (2004) 249–262.W.-K. Chen, Linear Networks and Systems (Book style). Belmont, CA: Wadsworth, 1993, pp. 123–135.","B. Remki, K. Abahri, M. Tahlaïti, R. Belarbi, «Hygrothermal Transfer In Wood Drying Under The Atmospheric Pressure Gradient», International Journal of Thermal Sciences, Article in press, 2012.","Fortin, O. Millet, G. De Saxe, Numerical simulation of granular materials by an improved discrete element method, Journal of Computational and Applied Mathematics 168 (2004) 207–213.","L.Z. Zhang, Numerical study of heat and mass transfer in an enthalpy exchanger with a hydrophobic–hydrophylic composite membrane core, Numer. Heat Transfer A 51 (7) (2007) 697–714.","Y. Jen, Liu, Solutions of Luikov equations of heat and mass transfer in capillary-porous bodies. International heat and mass transfer, vol.34. No.7, pp.1747-1754, 1991.","J. Fan, X. Cheng, Y.S. Chen, An experimental investigation of moisture absorption and condensation in fibrous insulations under low temperature, Experim. Therm. Fluid Sci. 27 (2003) 723–729.","W. Chang, C. Weng. 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El ganaoui, M. Khelifa, and S. Gabsi, \"an example of feasibility study of eco materials production chain and bio-based products for eco-construction/renovation in the named greater region (belgium, france, luxembourg),\" International Conference On Materials and Energy, Tetouan-Morocco, 2015."]}

The present study is focused on the analysis of a Simple Solar Distiller (SSD) and a Simple Solar Distiller Hybrid with Heat Pump (SSDHP) plants. Experiments have been conducted for 17 h as True Solar Time (TST) for climatic conditions of Gabes (southeast region of Tunisia), during the months of June and July 2006 for four configurations of the above-mentioned plants. Data obtained from experimental conditions are used to determine values of convective and evaporative heat transfer coefficients as well as experimental and theoretical yields. It was found that the SSDHP configuration exhibits better results than the SSD one. In this case, the convective heat transfer coefficient is found equal to 2.373 W/m2 °C and the experimental yield is equal to 1.8 l/m2 h.