Modeling and analysis

For the auditorium which is 72 feet in length, 36 feet in width with a height of 22 feet the client suggested a mechanical cooling system which would have an airflow rate inside the space as 32,000 CFM. The outlet grill is located at a height of 15 feet above ground level. The floor was designed with radiant tubing underneath which was maintained at 2oF above the dew point temperature inside the room. A length wise displacement diffuser is located at 8 feet above the ground with fresh air flowing at 55oF DBT and 60% RH. Further, the sources of heat gain were identified in consultation with the client and they were appropriately modeled numerically in the CFD software.

Figure showing the temperature in the auditorium as per ASHRAE design before optimization


Figure showing the temperature in the auditorium after optimization using CFD

Conclusion

The optimization of the mechanical cooling system inside the Columbia college auditorium was conducted using the CFD tools. Using Computational Fluid Mechanics the client eventually reduced the size of mechanical systems by 50% which brought them an effective cost saving of approximately $ 250,000. The results clearly showed a thermal stratification where the temperature is maintained at 75 degrees Fahrenheit till a height of 8 feet and the relative humidity is maintained at 50% to 60%. The effective cooling is done only till the height of 10 feet, thus reducing the energy consumption by the mechanical devices and the system as whole. Further, it is also observed that depending on the positions of light fixtures the effective cooling provided by the radiant floor varied from 10 Tonnes – 15 Tonnes