Methodology for the Evaluation of Natural Ventilation in ... - Cham

Figure 49. Comparison of Single Zone CFD Model without and with Heat Loss through AtriumWallsA CFD simulation was also created to evaluate the influence of the working fluid used on theresulting flow pattern. The single zone case was used due to its simplicity and the ability tocalibrate the CFD model with existing data. Data were provided for a single-zone, reduced-scalewater model of a similar configuration of a single heated zone connected to an atrium. However,the reduced-scale water model was not geometrically similar to the reduced-scale air model.These data were used to validate a CFD model with the geometry of the original water model,and then the CFD model was modified to be geometrically similar to the reduced-scale airmodel. The ideal air model simulation was used, with no heat loss through the envelope. Theresulting temperature distribution is provided in Figure 50. The temperatures have been scaledusing the reference temperatures, so that they are comparable. The inlet jet at the windowdissipated quite differently for the two fluids. The jet in the air model spreads along the floor ofthe heated zone, reaching the far end of the atrium wall, while the inlet jet in the water model justreaches the junction between the heated zone and the atrium. The temperature stratificationpatterns within the heated space also differ with the working fluid used. The warm fluid in theheated space permeates lower into the heated zone in the air model than in the water model, dueto the differences in thermal properties of each fluid.125