Submitted by Maria.Kapsalaki on Mon, 05/11/2015 - 14:38
A number of interzonal models have been developed to calculate air flows and pollutant transport mechanisms in both single and multizone buildings. A recent development in multizone air-flow modeling, the COMIS model, has a number of capabilities that go beyond previous models, much as COMIS can be used as either a stand-alone air-flow model with input and output features or as an infiltration module for thermal building simulation programs. COMIS was designed during a 12 month workshop at Lawrence Berkeley National Laboratory (LBNL) in 1988-89.
Age of air is a technique for evaluating ventilation that has been actively used for over 20 years. Age of air quantifies the time it takes for an elemental volume of outdoor air to reach a particular location or zone within the indoor environment. Age of air is often also used to quantify the ventilation effectiveness with respect to indoor air quality. In a purely single zone situation this use of age of air is straightforward, but application of age of air techniques in the general multizone environment has not been fully developed.
Predicting the performance of natural ventilation is difficult, especially for the large scale naturally ventilated buildings, because of the lack of accurate and efficient prediction tools. This paper presents a strategy, integrating a multi-zone model and computational fluid dynamics (CFD), to improve natural ventilation prediction and design. Large openings and atrium are broadly used in naturally ventilated buildings to promote buoyancy force and optimize air movement. How to properly deal with large openings and atrium is discussed and compared in this paper.
We present in this paper an advanced formulation of zonal models for calculating room airtemperature and airflow distributions. It is based on a new way of sub-dividing the room usings the Octree method. It allows us to obtain a partitioning based on airflow patterns. The behaviour of the room is represented by the connection of SPARK calculation objects according to its partitioning. The SPARKs objects represent sub-zones of the room or interfaces between sub-zones. We developed an automatic generator of zonal models.
The behaviour of solid contaminants in air flow is important for identifying those in variouslocations in ventilated space. The main reason for this study is to find out where different-sized particles can be found in a room using a simple particle-settling model. In this investigation two distinctive particle sizes are considered, i.e. 0.5 m and 10 m. Additionally, two different ventilation configurations are used to examine how this influences the particle concentration.
Seeking to realistically model details of room airflows, researchers have recently embeddeddetailed CFD or sub-zone (zonal) models within multi-zone idealizations of building systems. However a number of issues remain to be resolved to assure the success of this approach. Foremost is the question of zone resistance which is ignored in multi-zone models yet implicitly included in CFD and sub-zone models.This paper defines a fundamental means to measure zone resistance and presents the results of CFD studies to evaluate its relative significance for representative geometries.
The paper deals with a numerical investigation of the influence of ventilation and airconditioning on the distribution of pollutant concentrations in buildings. The model used is acoupled thermal and airflow model where the room is divided into 18 sub-zones.Temperatures and pressures are determined from the mass and energy conservation equationsin each sub-zone, while airflow rates between two adjacent sub-zones are determined from theBernoulli equation.
This paper presents a transient periodic heat transfer analysis of non-air-conditioned multizonebuildings taking into account the effects of heat fluxes through various facades ofbuildings including windows, air ventilation and infiltration, furnishings and ground heatconduction. A user-friendly computer software has been developed for the above mentionedpurpose. The validity of the analysis and the building simulation software has been checkedby comparing the results with those obtained by running commercial software SUNCODE forthe same input data.
The intent of this paper is to show that using Equation 6-1 from ASHRAE standard 62 based on occupancy is a non sense if used as a control algorithm in so far as up to now no sensors can physically count each individual in the space. Equation 6-1 describes how to calculate the amount of outdoor air required from an air-handling unit serving multiple spaces for system design purposes.
The new model of the COMIS program has been modified, it allows individual rooms to be divided into smaller zones. This new program has been evaluated and the results have been compared to those from other zonal and CFD models.