Étude des performances thermiques d’un réfrigérateur local basé sur l’évaporation de l’eau à travers une paroi poreuse en argile cuite

Dans cette étude, un dispositif de réfrigération basée sur l’évaporation de l’eau à travers une paroi poreuse en poterie est conçu, simulé et expérimenté. L’architecture originale de ce réfrigérateur local a été conçue à partir de l’idée d’optimiser les paramètres pouvant influencer son fonctionnement tout en minimisant le volume d’eau à évaporer à travers la paroi poreuse. Les résultats montrent que le fonctionnement du réfrigérateur est fortement influencé par les trois paramètres physiques dont dépend essentiellement l’évaporation de l’eau à travers un milieu poreux (la température et l’hygrométrie de l’air et la surface totale d’échange). L’analyse des courbes expérimentales et théoriques (simulation) montre que la température de l’eau du réfrigérateur ne peut être abaissée au-delà de la température de bulbe humide de l’air évaporateur. Un tel réfrigérateur en argile cuite aurait de possibles applications dans les cuisines et les Jardins pour la conservation des denrées, en campagne pour le rafraîchissement, sur les airs d’autoroute, dans les parcs nationaux et sur les campings des régions méditerranéennes.Mots-clés : paroi poreuse, saturation, eau, réfrigérateur, évaporation, température de bulbe humide, argile cuite.Study of thermal performances of a local refrigerator based on water evaporation through an earthenware porous wall. In this study, a system of refrigeration based on water evaporation through a porous wall in earthenware is designed, simulated and tested. The original architecture of this local refrigerator was conceived from the idea to optimize the parameters being able to influence its operation while minimizing the volume of water to be evaporated through the porous wall. The results show that the operation of the refrigerator is strongly influenced by the three physical parameters on which water evaporation through a porous medium mainly depends on (temperature, relative humidity of the air and total surface of exchange). The analysis of the experimental and theoretical curves (simulation) shows that the temperature of the refrigerator water cannot be lowered beyond the wet bulb temperature of the evaporating air. Such an earthenware refrigerator would have possible applications in the kitchens and the Gardens for the conservation of the food products, in the countryside for cooling, on the motorways air, in the national parks and on the camping areas of Mediterranean regions.Keywords : porous wall, saturation, water, refrigerator, evaporation, wet bulb temperature, earthenware.Article text in Frenc

Experimental study in natural convection

The study of thermal and ventilation parameters, obtained in a transient, laminar solar chimney of reduced dimensions, (1 < m <3) m with a square collector (side = 2m) is presented. Experimental measurements has been made to determine the temperature of the absorber and the fluid in the collector, it is shown that at the entrance of the chimney, the temperature of the absorber decreases slightly while that of the fluid is maintained at a maximum level. Temperature differences were observed up to 32°C between the atmosphere and the fluid in April. A temperature variation at the absorber depending on the stack height is presented. Temperature measurements in the chimney, at various heights depending on the axial coordinate, show a variable temperature profile. It is, from these, shown that, in the selected interval of stack height, the average speeds of output increase linearly as a function of stack height. For a chimney of 3m in height and 20cm in diameter, a maximum speed of approximately 0.7 ms-1 was observed. The lack of appropriate equipment handicaps the velocity measurement at the chimney entrance. Thus, the results of simulations with the computer code COMSOL 5.1 has confirmed temperature values measured at the chimney entrance and after this, velocity values are determined.KEYWORDS: 1- Solar chimney, 2- Laminar convection, 3- Temperature, 4- Outlet velocit