Lahcen Boukhattem

Energy efficiency in buildings: Thermophysical characterization of building materials

In Morocco, the construction sector is the largest consumer of energy. Reducing the energy consumption in buildings represents a major economic and ecological issue. The building sector has the highest potential for improving energy efficiency which concerns, among other the choice of appropriate materials and improvement of their thermal characteristics. The present work deals with measurement methods and characterization of thermophysical proprieties of building materials. Primary results of measurement of thermal proprieties of extruded polystyrene, expanded polystyrene, soil, gypsum and marble are presented. The measurements were carried out using two devices available at the National Centre for Studies and Researches on Water and Energy (CNEREE) at Marrakech. The two devices EI700 and FP2C use respectively the boxes method and the method of the hot plan and hot wire.

Numerical simulation of thermal convection in a closed cavity in the presence of a thin horizontal heated plate

In this work, a numerical study of heat transfer by natural convection in an air filled two-dimensional closed cavity in the presence of a thin heater plate is presented. The vertical walls are assumed to be adiabatic, while the horizontal ones are maintained isothermal. The equations governing the natural convection in the cavity are solved using a finite difference technique based on the control volume approach and the SIMPLEC (Semi-Implicit-Method for Pressure-Linked Equations Corrected) algorithm. A non-uniform mesh in both directions, constructed by using a geometric progression, is adopted. The square cavity contains a thin heated plate located at the cavity center with an aspect ratio equal to 0.5. The heater plate is positioned horizontally and has a higher temperature than the isothermal walls. The simulation results are obtained in terms of velocity vectors and isotherms for different Rayleigh numbers values ranging from 10 4 to 10 6 . The symmetric boundary conditions produce a symmetric behaviour of temperature and velocity fields according to the central vertical plane. The increase of Rayleigh number leads to increasing importance of convection heat transfer relative to the conduction heat transfer. The fact is more marked for the regions above the heater plate. It is shown that for high Rayleigh numbers, heat transfer from the heater plate to the isothermal horizontal walls is mainly directed towards the top wall.

Dynamic modelisation of heat transfer between the ground and shallow basment of a villa in Marrakesh area

In this work, we propose to study the heat transfer between the ground and shallow basement in the Marrakech city-Morocco. It is a matter of shallow basement of a villa called “Villa Amer Ben Slama”. The concerned part of this villa was modeled by the dynamic simulation software TRNSys using the 1244 type in order to calculate the heating load and cooling one of the studied building. The temperature measurements in different rooms of shallow basement were conducted, during two periods (summer and winter periods) to validate the simulation results. The effect of the climate conditions on the thermal loads and the comparison of the energy consumption between the shallow basement and the two floors (first and second floors) were examined in this work.

A three-dimensional numerical simulation of heat exchanges between the ground and shallow basements in Marrakech

This work deals with a numerical study of three-dimensional heat transfer between the ground and shallow basements in the town of Marrakech (Morocco). The equation governing heat transfer was discretized by the finite difference method and is solved using the alternative direction implicit (ADI) scheme. The objective of this work is to study the effect of the distance L the soil type, the walls type of the cellar, the walls thickness and the geometry of the cellar on the energy exchanges between the ground and the shallow basements building for real climate of Marrakech. The results obtained show that these parameters influence the flows exchanged between the ground and the building.