DISH STIRLING SYSTEM POTENTIAL ASSESSMENT FOR EIGHT MAIN SITES IN MADAGASCAR

International audienceSolar energy is a green and attractive renewable energy source that can be converted for power generation. The objective of this work is to evaluate the potential of dish Stirling systems if they are used in the fourth worldwide largest island of Madagascar. For that purpose, a theoretical model of the dish Stirling system based on the geometrical configuration and heat transfer was developed and coded on Matlab. Simulations were run to investigate the energy efficiency variation of the system for eight main sites in Madagascar. As results, the proposed model enables to represent the system thermal behaviour to assess its efficiency. Among the eight studied sites, those which are on the coastal zones are more propitious to the dish Stirling system. While, in the north and northwest, the sites of Diego Suarez and Majunga present high efficiencies with, respectively, 31.65(%) and 31.07(%), it is in the south in fort-dauphin that thermal efficiency rate is maximal with 32.17(%). Convincing results that suggest that the implementation of this kind of facility will solve a large part of energy supply problems in these regions

Co-valorisation énergie et matière des résidus agricoles par pyro-gazéification

Agricultural-residues are interesting bioenergy resources at the territory scale of Madagascar. Their use as feedstock is essential in order to solve energy precariousness especially in rural areas. Pyro-gasification is a promising thermochemical process which converts carbonaceous materials like biomass residues into syngas. Two types of agricultural-residue from rice production were studied: rice husk (RH) and rice straw (RS). Physico-chemical and thermal analysis revealed the low heating values of these residues but with high ash concentration due to inorganic elements. Experiments performed on reactor at laboratory scale showed that thermochemical conversion produces syngas, biochar and tar. Physico-chemical characterization analysis of these products were conducted while prospective analyses of their applications were suggested. A pyro-gasification model was developed based on equilibrium and kinetic reaction methods. The simulation results are in good agreement with data from literature. Global sensitivity analysis (GSA) was carried out in order to determine key parameters for exergy efficiency optimization of pyro-gasification process.Les résidus agricoles constituent un potentiel bioénergétique important à l’échelle d’un territoire comme Madagascar. L’utilisation de ces ressources locales comme vecteurs d’énergie est primordiale afin de diversifier et trouver des solutions alternatives à la précarité énergétique notamment en milieu rural. La pyro-gazéification est un procédé thermochimique très prometteur pouvant convertir des matrices carbonées solides, comme les résidus de biomasse, en gaz de synthèse (syngaz). Deux types de résidus agricoles, balle de riz (RH) et paille de riz (RS), ont ainsi été étudiés. Les analyses physico-chimiques et thermiques des résidus bruts de RH et RS ont révélé de faibles pouvoirs calorifiques par rapport à d’autres types de biomasse, mais avec une forte teneur en cendres, typique de la présence d’éléments inorganiques. Les expérimentations sur réacteur à échelle laboratoire ont montré que les produits issus de la conversion thermochimique se présentent sous forme gazeux (syngaz), solide (biochar) et liquide (goudron). Des analyses de caractérisations physico-chimiques de ces produits ont alors été réalisées et des analyses prospectives de leur valorisation sont suggérées. Un modèle de réacteur de pyro-gazéification des résidus agricoles a été développé en se basant sur l’équilibre chimique et la cinétique des réactions. Les résultats de simulation sont en accord avec ceux dans la littérature. Une analyse de sensibilité globale (GSA) sur le modèle a été réalisée afin de déterminer les paramètres clés influençant le rendement exergétique du processus de pyro-gazéification

Techno-Economic Investigation of a Thermal Cure Center Excess Heat Recovery System for Producing Hot Water for a Hotel in Antsirabe Madagascar

Energy saving is a significant feature to take in account in the choice of renewable energy technologies to use. This paper techno-economically investigates an excess heat recovery system that is proposed to be installed in a thermal cure center geothermal source for producing domestic hot water to be conveyed through piping to a nearby three star hotel located in Antsirabe Madagascar. For that purpose, the hotel hot water needs were determined by using an available online free code, called Solo, and the effectiveness-NTU method was used to size the plate heat exchanger to be used to recover the geothermal heat. The proposed hybrid geothermal solution performance was compared with that of hybrid solar energy water-heaters in terms of electricity consumption related to water temperature adjustment. It follows from comparison results that the proposed hybrid geothermal solution is more profitable and allows about 73.2 (%) of electric energy saving while it is 54.9 (%) for hybrid solar option. Besides, economic evaluation confirmed that the geothermal installation allows a shorter return on investment more favorably

Modélisation et analyse de sensibilité globale d’un toit vert en zone tropicale humide

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Numerical investigation of green roof performance

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Generalized protocol by systemic analysis for dimensions of a small scale gasifier engine system dedicated to the electricity generation from biomass

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GIS-based approach to identify climatic zoning: A hierarchical clustering on principal component analysis

International audienceIn tropical environments, the design of bioclimatic houses adapted to their environment is a crucial issue when considering comfort and limiting energy needs. A preliminary part of such design is an accurate knowledge of the climatic conditions in each region of the studied territory. The objective of this paper is to propose climatic zoning from a database of 47 meteorological stations in Madagascar by investigating hierarchical clustering on principal components. Then, theses results are combined with a spatial interpolation using a Geographic Information System approach. This step allows us to define three climatic zones corresponding to dry, humid and highland zones. These results make it possible to define standard meteorological files that are used to evaluate the thermal performance of traditional Malagasy houses. Regardless of the type of house and the areas considered, the percentage of comfort, according to Givoni bioclimatic chart, varies from an average value of 20 % to 70 % without ventilation and with an air velocity of 1 m/s, respectively. It can be concluded that Madagascar's traditional habitat has adapted over time to the constraints of its environment