modelling

The work presented in this paper was done in 1997 as a final thesis in mechanical engineering, supervised by TRANSSOLAR Energietechnik GmbH in cooperation with the Institute for Thermodynamics and Heat Technology (ITW), University of Stuttgart. The contents of the work is the investigation of natural ventilation through window openings (single sided and cross ventilation) in an existing office space. Both measurements and computer simulation have been conducted.

Smoking restrictions in the workplace and increased health consciousness at home have seen a sizable reduction in the number of spaces where smoking is permissible. The aim of this study was to investigate the effects of ventilation in public houses, one of the few remaining public spaces where smoking is still socially acceptable. Little is known about the situation with shared occupancies, where relatively large areas are intended to accommodate both smokers and non-smokers.

Rooms with high windows are likely to have comfort problems caused by cold airdowndraught, which are usually solved by placing heating appliances underneath thewindows. In the city of Zug, Switzerland, a highly insulated educational building with aconcrete core system for heating and cooling is planned. The purpose of our investigation wasto find out whether any measures are necessary in this building to compensate the effects ofdowndraught in the occupied zone. Special attention has been paid to the effect of passivemeasures like air flow obstacles or openings in the window sill.

The purpose of this study is to provide a model to facilitate the simulated evaluation of theenergy consumption for different mushroom house and climate set point configurations.Climate management in this application is complex, including control of: oxygen, carbondioxide, and water vapour, temperature, evaporation rate, air cleanliness, and indoor-outdoorpressure differential. Climate set points vary according to the stage of crop growth and need tobe maintained regardless of weather conditions.

This paper compares two well-known modelling approaches for natural ventilation in a multi-zone building with thermal stratification and large openings. The zonal approach in this paper assumes a fully mixed condition in each zone, and considers the bi-directional flows through all large openings. The zonal model is integrated into a thermal analysis code to provide simultaneous prediction of both ventilation flow rates and air temperatures in each zone. The CFD approach uses a finite-volume method for turbulent flows.

A series of CFD and model experiments were carried out in order to find the most effective ventilation system in a separated refuse disposal facility. The ventilation system needed in the facility protects the working space from dust and odors generated by handling refuse. The desired ventilation system is to introduce the outdoor air from the one side of the working area and to exhausts the contaminated air through the opposite side of the refuse stock yard, so-called the unidirectional airflow ventilation.

A data acquisition system which uses a computer provides a more useful analysis system. Since the processing speed of computer is continuously increasing, the information than it is possible using conventional data acquisition systems. However, the raw measurements also include the signal noise which may lead to difficulty when the signal is analyzed. This work assesses an algorithm for removing possible signal noise, usually with high-frequency, from the measurement of tracer gas concentration.

Solar chimneys are often used to extract air from a building by thermal stacks, while subfloor plenums are used to passively cool air before it is supplied to a building. This paper examines the overall flow pattern in buildings with both solar chimneys and subfloor plenums. For a multi-zone flow system in which each zone has only two effective openings, an analytical solution is derived. A sufficient condition for upward flows to occur is derived from the analytical solution.

Studies of airflow between two adjacent spaces of building were carried out using CFD simulation. The results of CFD simulation were validated against test data set obtained from full-scale experimental tests. The agreement and discrepancy between the prediction and measurement results were discussed. Further numerical exercises were carried out to study under the conditions that were difficult to achieve by experiments and the results obtained were supplemented to the understanding of convective heat transfer between adjacent rooms.