Ababacar Thiam

Impact of window to walls ratios on thermal comfort and energy consumption in tropical zone

This paper investigated the impact of Window to Wall Ratios (WWR) an the thermal comfort and energy lighting demand of a building in tropical zone. Simulations were carried out for a reference office proposed by Task 27 of IEA using three Window to Wall Ratios (WWR). Results were analyzed both in terms of operative temperature and energy lighting consumption. Simulations results showed that for increasing WWR, the operative temperature increases and energy lighting demand decreases.

Exergetic Optimization of Absorption Chiller Single Stage H2O-NH3 by Experiments Design Method

Single stage absorption chillers using H2O-NH3 have received increasing research interest in recent years, in order to make them competitive with conventional refrigeration machines. This work presents a study on the performance of such tri-thermal machines, used for negative temperature refrigeration. The objective is to determine the values of the system operating temperatures that minimize the irreversible losses in the various heat exchangers. To do this, the overall exergy efficiency of the system has been expressed as a function of the various operating temperatures. This objective function is to be maximized with experimental design method. The normal probability plot of the residual indicates that the random errors for the process are drawn from approximately normal distributions. From the results, with exergy efficiency greater than 0.4, two operating modes are presented which can be with condensation temperatures below 32 °C and above 38 °C.

Lighting controls and energy savings potential in tropical zone

Reducing global energy consumption is a challenge to limit the rise in average earth temperature. The use of lighting controls in the building leads to energy savings. The objective of this study is to evaluate the energy savings potential in buildings in tropical zone due to lighting controls. The results of the simulations show that 47.6% of energy savings could be obtained with a dimming control and 33.3% with an on/off control in this office considered.

Preliminary study of a small beam-down solar tower on sub-Saharan countries

In this present work, a small Beam Down power plant is studied in the Sahel region. The preconfigured system is a field of 78 heliostats and a hyperboloid sectioned with a length rhyp = 11.72 m. The simulation made with the software SolTrace shows an efficiency of the field up to 89%. Temperatures from 675.37 K to 809.55 K are achieved and the power intercepted at the receiver input are equal to 96.57 kW, 124.53 9 kW and 98.90 kW respectively at 9 am, 1: 06 pm and 4 pm.

Study and modeling of a pressurized air receiver to power a micro gas turbine

In the present work a solar receiver with reticulated porous ceramic foam bounded by two concentric cylinders, horizontal axis and length L is selected and studied. A receiver pre-sizing study based on the optimization work of Hischier allowed us to find the dimensions and the receiver input variables. We have developed a mathematical model based on the Representative elementary volume to model the flow and heat transfer within the absorber. The numerical solution of equations set was obtained with FLUENT. The power of 75 kW wanted in this study is obtained with a thermal efficiency equal to 87%. The fields of temperature and velocities from the simulation are analyzed and it is clear from this study that the temperature profiles show the excellent ability of the receiver to transfer the heat to the fluid. The influences of the porosity and mass flow on the thermal efficiency are analyzed also. It emerges from this study that the mass flow rate and porosity are very critical parameters on the thermal perf...