Experimental and Numerical Study of Airborne Contaminants Transmission in Hospital Isolation Rooms Equipped with Protected Zone Ventilation

Abstract

Experimental tests have been conducted in the small test chamber at the Norwegian University of Science and Technology. The purpose has been to examine air flow path and airborne pollutant distribution, in the case study of an airborne infection isolation room (AIIR) configuration. This configuration uses the concept of protected zone ventilation (PZV) including a combination of a localised air supply system and an air curtain at four air change rates per hour (6, 9, 12, 15) and two negative pressure differences between the outside and inside of the isolation room (2.5 Pa and 5 Pa). In this study, three scenarios, (a) without an air supply curtain, (b) with the 45° and (c) with the 90° air supply curtain, were investigated experimentally and numerically. The N2O tracer gas was employed to simulate airborne transmission of infectious agents throughout the experiment. In the CFD simulation, viscous effects have been included using the (RNG) k–ε turbulence model with species transport model. The simulated domain has been meshed using the structured mesh with hexagonal cells and with a uniform resolution of 0.0175m, resulting in a total of over 6 million cells. The scenario with the 45° supply air curtain significantly decreased the gas concentration already at 6 air change rates per hour. At the same time, the negative pressure difference of 2.5 Pa had the lower gas concentration in two scenarios (a) and (b) while 5.0 Pa in scenario (c).

Keywords: Airborne infection isolation room, Contaminant distribution, Protected zone ventilation, tracer gas, Computational Fluid Dynamics (CFD)