Optimal design and control of buoyancy-driven ventilation

Relationships between airflow rates and opening areas of importance for design and control are analysed for buoyancy-driven ventilation in a room with two openings and uniform temperature. The optimal ratio between the inlet and outlet areas is found. The consequences of deviations from the optimum are discussed. Also, discussed are measures to be taken in order to avoid bidirectional flow in any of the openings, and it is discussed how to ensure constant airflow rate, when structural restrictions imply reduction of inlet or outlet. The analyses are carried out with the temperature difference and the net heat input, respectively, as independent, thermal variable.