A study on the arrangement of air inlets in a Class 7 clean room

Abstract

In this paper, a room with four inlets located at the ceiling in the centre of the room with an exhaust installed at the bottom sidewall was modelled and investigated. The air is supplied through the individual room air inlets filtered by a high-efficiency particulate air filter, and the air is removed from the room via the exhaust located at the bottom sidewall. It leads to two possible inlet arrangements with four inlets: 1 × 4 array and 2 × 2 array. In the modelling, an obstacle is built to represent a workbench located underneath the inlets. Both the array designs are compared on their air flow and ability to remove gaseous contaminants. This study also suggests that the behaviour of the air jet impingement on the surface of the obstacle must also be considered in determining the design of the inlet array in a clean room. Practical application: This paper is intended to provide a practical guide to building service engineers on the design arrangement of inlets for a Class 7 clean room. By using the same concept, the design arrangement concept can be extended to the sizing of a workbench (i.e. the obstacle) when there is a fixed inlet design.

Effect of turbulent and laminar flow mechanisms on airflow patterns and CO2 distribution in an operating room: a numerical analysis

“…The conservation equations were solved using the finite element method for the steady-state condition and pressure-based solver was used for the simulations. Moreover, the second-order method was used to discretize the momentum, energy, and turbulence conservation equations [31,32]. The RNG k-ɛ model is applicable and recommended for displacement airflow [33], but for an OR, due to the relative low level turbulence, the standard k-ɛ model is more applicable for predicting the airflow [33,34].…”

“…For natural convection, the Boussinesq approximation was used, and the SIMPLE algorithm was utilized for pressure and velocity coupling. The convergence criteria for the energy was considered as 1×10 -6 , and 1×10 -3 for continuity, velocity, k, and ɛ [31]. Convergence criteria for other species are set at 1×10 -3 .…”