Impact of the Speed of Airflow in a Cleanroom on the Degree of Air Pollution

Abstract

The high-energy requirements of cleanrooms are the main motivation for optimizing their operational conditions. The ventilation system consumes the most energy in order to ensure the precise air conditioning of the room (filtration, temperature, and humidity adjustment). The main function of the ventilation system is to keep particle concentration to a minimum. This work deals with the optimization of an experimental operating room via the optimization of air supply through the distribution element (laminar airflow ceiling) in the range of 0.15–0.25 m·s−1. The laminar airflow between the distribution element and the patient is influenced by the operating light and different airflow velocities. These factors affect changes in particle concentration. Ansys Fluent software was used to investigate the nature of the flow, velocity profiles, and particle trajectories. The results of our numerical simulation demonstrate that a suitable flow rate setting increases the efficiency of particle reduction in the operating table area by up to 54%, which can, in turn, reduce operating costs. The simulated air velocity profile was subsequently verified using the particle image velocimetry (PIV) method. The typical size of particles monitored for in cleanrooms is 0.5 μm according to ISO EN 7. Therefore, the results of this study should be helpful in correctly designing distribution elements for clean rooms.

Application of Biofluorescent Particle Counters for Real-Time Bioburden Control in Aseptic Cleanroom Manufacturing

“…The results of this study support that outcome, as the BFPC results correlate well with particles and may also be used to continuously control the bioburden status of a cleanroom with early warning possibilities in case of high microbial values. This is in line with the study results of Mičko et al [11], who found that 'lower flow rates reduce unwanted turbulence and the magnitude of velocity fluctuations, making the ventilation system more efficient at removing contaminants . .…”

“…Energy savings by means of reduced ACRs has been described by various authors [6,11,37]. In a previous publication by Behrens et al [10], which focused on a regulatory limit values for particles >0.5 µm and >5 µm, it was stated that ISO 8 cleanroom operations can be performed with lower ACRs than 20 h −1 .…”

“…As this not only generates costs, but also has a negative impact on the CO 2 -footprint of the company, manufacturers are in a dilemma: On one hand they need to supply the required amount of air into the production area with a certain safety buffer to avoid deviations from cleanroom specifications, on the other hand they are faced with the need to save energy as much as possible. A reduction of the air change rate (ACR) would be a possible approach, as various studies have shown [7,10,11].…”

Optical Particle Visualization Technique Using Red–Green–Blue and Core Storage Shed Flow Field Analysis

“…Mičko, P. et al [17] studied the effect of air pollution on the airflow rate in a clean room. Velocity and particle trajectories were investigated using Ansys Fluent and subsequently validated using the PIV method.…”