Analysis of HVAC Configurations for Hospital Operating Room
ASHRAE Annual Conference, Long Beach, CA, 2017
A probable factor in minimizing the infection due to airborne bacteria in the hospital operating room is to minimize the entrainment of air from the non-sterile zone into the sterile zone. Previous Computational Fluid Dynamics (CFD) study of a legacy HVAC design of a hospital operating room indicated, irrespective of the air change rates (ACH), when the airborne particulates originate in the non-sterile zone they get entrained back into the sterile zone. This study evaluates whether modifications in the legacy HVAC configuration can help alter the flow path of these contaminants and mitigate the issue of particulate entrainment. Two conceptual modifications in the legacy HVAC design analyzed in this CFD study indicate such strategic modifications can alter airflow patterns and resulting flow path of airborne particulates which can further help in reducing the entrainment into the sterile zone. When the exhaust grills are placed in the ceiling with a small barrier around the sterile zone, the entrainment of particulates from the non-sterile zone into the sterile zone reduced significantly and lowered the temperature in the non-sterile zone. In the other design modification where additional laminar supply diffusers placed in the non-sterile zone surrounding the array of laminar diffusers in the sterile zone, the discharge air jets in the non-sterile zone drifted towards the sterile zone. Thus, in this case the particle movement from the non-sterile zone to the sterile zone did not show any significant improvement over the legacy design. In order to sweep the particles effectively from the non-sterile zone, such design may require careful adjustment of the flow split and balancing of discharge air velocities between the sterile and non-sterile zones. Additionally, impact of these design modifications on the acceleration of centerline velocity of the supply air jet is evaluated.