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.
The solar cell is assumed to be under light concentration (C=50 Suns) which leads us to take into consideration the electric field induced by electrons concentration gradient. We also take into consideration temperature influence on electron and hole diffusion parameters, on carrier generation rate, on carrier intrinsic concentration and on silicon energy gap. It emerges from results analysis that increase in temperature leads to decrease of open-circuit voltage and the photovoltaic parameters at the maximum power point (MPP) such as electric power, photo-voltage and photocurrent with however a slight increase of short-circuit photocurrent density. It also appears that temperature has a double effect on electrical parameters. The temperature dynamic effect which is characterized by parameters variations linked to operating point displacement caused by temperature variations. And the temperature proper effect which is characterized by parameters variation with temperature at a given operating point. Thus, the combination of these two effects represents temperature effective effect.
Thermal comfort is one of the most important requirements that scientists and building designers must meet to ensure the indoor air quality knowing its importance on productivity and the health of occupants. However, it has never been of great concern for architects and architectural historians and seldom explores it. Buildings are the large consumer of the most energy consumption (around 40% worldwide) and generate around 35% of GHGs like CO 2 that leads to extreme climate change. Hence, general and specific eco-friendly solutions in the field of building construction are required. Analysis of this study shows that air conditioning consumption can be significantly reduced thanks to the compressed earth bricks and by taking into account the climate and the orientation of the facades. However, this paper establishes viable low-cost option of building energy consumption while maintaining the thermal comfort and good indoor air quality. This work explains the effect of a single residential room orientation, by reducing the thermal amplitude, and improving the thermal phase shift in Ouagadougou climate conditions in April. Internal temperature was modelled with 8 cardinal orientations. The result corresponds to a decrease of thermal amplitude damping greater than 4˚C between East-West and North-South sides and, with a thermal phase shift of 4 hours 30 minutes between the Nord and West walls.
The energy demand in buildings sector is always increasing due to the climate, the economic growth, and also the need for thermal comfort. The aim of this paper is to find a way that can significantly reduce the energy demand for a building through an improvement of the design of its thermal envelope. Within this work, we utilized the thermophysical properties of four building materials: three local materials (compressed earth block (BTC), lateritic block (BLT), and raw earth), and one modern (Hollow cement). The numerical optimization of the building design has been performed dynamically by Comsol 5.3a software: the case study is Ouagadougou and the surface is 100m2. Also, the temporal variations in the inside of the room, as well as the internal and external temperatures of the walls and the ceiling with four different materials, have been determined. The result of the simulation shows that, for BLT, the maximum of ambiante temperature is obtained 308K around 22h, for Adobe it is 308.8K around 21h, for BTC it was 309.2K at 19h30, and finally for cement block it is 310K around 17. We can safely say that BLT is the material leading to the lowest average daily indoor temperature variation, thus leading to the reduction of air conditioning load and the need for thermal comfort and around the order of 4KW of energy saving can be obtained.
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