COMPUTER AIDED DESIGN OF FLOW REGIMES IN AIR CONDITIONED SPACES

Abstract

The present work was dedicated to the development and introduction of the flow heat transfer interactions on the air flow in the enclosure, and introducing the thermal conditions and the buoyancy term. The impact of flow parameters and factors (such as the configuration factors, flow conditions ... ) on the air flow pattern, will be studied. This work was employed with the aim for more comprehensive knowledge of flow characteristics in both isothermal and non-isothermal cases to give more insight and understanding of the flow movement. This offers the designer a better view of design limits to enable him to adequately select the optimum design from a wide number of alternative options and to use them in forecasting and even monitoring. So, the present thesis focuses on the numerical prediction as a suitable tool to analyze the parameters affecting the air distribution inside air-conditioned spaces. The k-c turbulence model is employed here to mode! the turbulence characteristics terms in the Navier-Stokes equations and the energy equation to perform the prediction. The program used here was originally developed by Khalil [, who constructed it to predict the flow field characteristics using the k-e model in the confined enclosures. This program was designed to obtain the characteristics of the flow field without the heat transfer interactions. In the present work, the fo!lowing preliminary contributions were aimed at: • Full 3-D scientific computations of flow regimes in air-conditioned enclosures including a comparison with actual full-scale investigations. • Mathematical fonnulation and solution of the energy equation in 3-D through the introduction of appropriate thermal boundary conditions and energy sources. • Performing parametric investigation to analyze the fluid flow regimes, heat transfer characteristics and turbulence effects on mixing Finally, some of the main conclusions are highlighted here: • The present modeling capabilities can adequately predict the local flow pattern and heat transfer in air-conditioned spaces . • Predictions demonstrate flow patterns and isothermal lines that are similar in form but differ in details under different operating conditions • The inlet air flow remains adjacent to the ceiling up to (X= 1.0 H) down stream the inlet opening, for the side wall inlets with ceiling effect. At this distance the air jet further expands and begins to drop towards the floor. • In non-isothermal flow situations with temperature variation in vertical direction, the buoyancy effects can be significant, coupling the governing equations through the buoyancy term is necessary. But if the buoyancy effects are small, the equations are uncoupled. In such a case the flow field is first obtained from the momentum equation, the obtained results are subsequently employed in the energy equation to obtain temperature distribution, see Jaluria et al • The determining factor, by which, coupled or uncoupled buoyancy effect are accounted, is the term Gr/Re, where both and Gr and Re are based on the inlet conditions. This term varied between 0.00 l to 0.5 in the cases discussed in the present work, Jaluria et a\?l