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

temperature of the air was the same as the temperature leaving the south half of the model. Thisimplied that some of the air from the atrium entered the second floor and warmer air exited at theceiling level. The data presented are for the stacks open case, which explains why there wassignificantly warmer air at the ceiling measurement point. In the heated zone, the temperaturepattern was similar for all of the wind speeds used (Figure 79). For each case, coolertemperatures were recorded at the mid-height of the heated zone. The actual temperaturecorresponded to the temperature of the exiting air from the ground and first floor south zones.Since there were no heating loads in the atrium space, the air exiting the south zones was driveninto the two zones on the north half of the model by the wind force. The air from the atriumspilled over the railing into the heated zones on the north half of the building, while warmer airexited at the ceiling level for both floors (Figure 69). Airflow visualization carried out forseveral different wind speeds verified this explanation for the temperature variation in the heatedzone (Figure 70) as did the CFD simulations (Figure 71). In Figure 77 and Figure 79, the coolestair temperatures correspond to the exiting air temperatures from the south half of the model,where the wind-driven air is entering the model. However, the heat sources at the floor andsome amount of radiation to the ceiling causes the thermocouples near the floor and ceiling torecord higher temperatures. Some of the cooler air enters into the first floor north half of themodel over the railing, causing cooler temperature measurements near the floor. There is someamount of jet flow, introducing the cooler air at the mid-height of the space. These flow patternswere visible with the airflow visualization technique and also provided with the CFDsimulations.Figure 70. Airflow Patterns for Reduced-Scale Air Model with Stacks Open: Combined Wind-Buoyancy Case144