Optimum fenestration characteristics in mediterranean Tunisian context: An energetic, economic and environmental (EEE) study

This paper aims to investigate the energy performance of several techniques integrated into the fenestration system of an office building. The first step was to compare the simulated and real energy consumption of a case study of an office building located in Tunis City. In a second step, the study explores the impact of a glazing retrofit solutions on annual energy saving. To determine the possible energy savings for the existing office building in various climatic zones, we performed several simulations, using the Design Builder software.For these zones, the optimum window-to-wall-ratio (WWR), ensuring a compromise between daylighting and energy consumption, is found to be 40%. Then, for the chosen WWR, we evaluated a retrofit process involving existing commercial technologies such as double-glazed insulated windows, as well as innovative technologies consisting of intelligent coating, in addition to passive techniques including several shading concepts.It is found that, the double-glazed window with outside reveal depth of 20 cm equipped with both low-emissivity (LoE) and electrochromic (EC) coatings ensures the lowest annual energy consumption. Besides, energy savings depends on the climate zone; it reaches 23% in hot climates (ZT3) and almost 20% in cold (ZT1) and temperate climates (ZT2). The possibility of using electrochromic coating was excluded following the economic study because of its exorbitant cost. In fact, this type of renovation can lead to payback periods of up to 74 years for the cases treated.The optimized window designs consist in using a double-glazing window with a LoE coating, an outside reveal depth of 20 cm, and as a shading system (Overhang). These designs save 8 to 20% of energy and reduce CO2 emissions by 6 to 10 kg CO2/m2 per year, with a payback period of less than 6 years depending on the climatic zone

Contours of Air and Brick Temperatures inside a Tunnel Kiln

International audienceWe present, in this work, the main results obtained from a two-dimensional numerical modeling of a tunnel kiln used for production hollow bricks. The results obtained made it possible to present contours of the temperature inside a tunnel kiln using a home-made two-dimensional code written with the open-source software SCILAB. The results showed the existence of a vertical temperature gradient in the brick stacks which can affect the final quality of the baked products

Thermal analysis on a novel natural convection flat plate collector with perforated tilted transparent insulation material parallel slats (TIM-PS) in Mediterranean climate

The purpose of this research is the evaluation of heat transfer by natural convection in an innovative flat plate solar collector operating in natural convection mode. The design consists of inclined, perforated slats of transparent insulation material installed between the absorber and the glass cover. Hourly climatic data on the four specific days of solstices and equinoxes was used to investigate the behavior of the novel collector design in the city of Monastir; Tunisia. A comprehensive process, ANSYS FLUENT, was implemented to properly evaluate the thermal performance of the collector. In order to obtain accurate thermal properties of the smart collector façade unit containing the TIM-PS to exploit in the simulation, a validated three-dimensional finite volume model developed using the CFD software was used to solve the conductive, convective and radiative heat transfer properties of the system. We have explored in depth the effect of optical characteristics of the TIM-PS on the collector performance. Present research focuses on the analysis of thermal efficiency profile of flat plate collector with innovative façade in comparison with conventional collector for different climatic conditions. The analysis indicated that innovative façade collector’s efficiency is highly influenced by solar intensity. It was found that TIM-PS façade can effectively reduce the convective heat losses through the front of collector. The simulation results show that perforated tilted TIM-PS offer better performance than conventional façade of collector during all the seasons of the year. Simulations performed for one year predict that with careful selection of the parallel slats properties, the new façade system can generate an efficiency up to 83% in June, 76% in September, 53% in March and 42% in December. The results of the thermal evaluation of this research will help guide the future development of this system, as we have demonstrated that the innovative façade collector can be used all year round. In conclusion, the TIM-PS have great potential and a very wide range of applications in the field of flat plate solar collector