English

Modern inlet devices applied in the field of ventilation of rooms are getting more complex in terms of geometry in order to fulfil the demand for thermal comfort of the occupants in the room and in order to decrease the energy consumption This expresses the need for more precise calculation of the flow jield. In order to apply CFD for this purpose it is essential to be able to model the inlet conditions precisely and effectively, in a way which is comprehensible to the manufacturer of inlet devices and in a way which can be coped by the computer resources.

Combined ventilation and heating systems in floors demand extensive investigations about the heat transfer before they could be installed in residential buildings. For basic investigation about the heat transfer two experimental plants with different duct geometries are build in a laboratory of the University of Essen. Especially the measurements of temperature on different places of the plants are taken to determine the heat transfer at the two floors.

Mechanical systems which use common ducts for combined heating and ventilating functions are becoming popular in the Pacific Northwest (U.S.). These systems range from simple fresh-air inlets ducted to the return side of a forced air heating s stem to more complex heat recovery ventilation systems utilizing the K eating ducts for air distribution. Typical integrated systems do not have heat recovery capability.

The basis of this study are experimental results obtained on a real scale cell in controlled climatic conditions which are used to show the potential influence of radiative participation of inside air on natural convection in a room. In a second part, a numerical analysis of flow patterns and heat transfer in a twodimensional thermally driven cavity containing a participating fluid is presented.

Application of hot wirelfilm ariemometry in room air flows presents difficulties because: (1) the effect of natural convection due to the heated wire beconies significant for low air velocity measurements; (2) the angle sensitivity of a hot wire becomes small at low air velocities, which makes it difficult to resolve the direction of each velocity component. This study aimed at quantifying the uncertainty of tlie hot wire anernornetry and examining the angle sensitivity of a hot wire in low air velocity measurements.

Inter-zone convection affects the general movements of air in a building and must be evaluated for accurate thermal zones heat and mass balance. The paper presents results of an experimental study of convective heat transfers caused by temperature difference between two zones connected by an opening of height 2. 05 m and varying width. Experiments were carried out in a full scale calorimetric chamber (5.5 m x 2.5 m x 2.5 m). Temperature differences were maintained by two active vertical walls locatedon either side of the doorway.

Both infiltration and exfiltration has a predominant influence on the space heating requirements in cold climates. Good predictive design methods are required to estimate the air leakage component in buildings. This predictive methods will be useful in implementing the air leakage control strategies for reducing the problems associated with air infiltration in both new and existing high-rise buildings.

Due to the limitations of computer storage and time the flow boundary conditions at an air inlet device have to be specified for numerical simulations of air flow patterns in rooms. With regard to this the present work gives velocity measurements near an industrial air inlet using a Laser-Doppler-Anemometer. From the stochastic velocity data the time-averaged velocity components, standard deviation and turbulent kinetic energy are evaluated.

A set of diagrams for estimating flow coefficients and exponents in the power law flow equation for cracks are presented. The diagrams are primarily intended for those who perform infiltration calculations by hand or by using a computer program for single and multi-zone infiltration and ventilation calculations. The error introduced by the estimation technique is compensated for by means of a correction coefficient with aspecific value in different pressure difference intervals. A computer program performing the calculations behind the diagrams is available for public use.

This paper is concerned with the application of air flow simulation in design. It describes the real world application - and the results of this with respect to building design improvement - of a building energy modelling system, ESP (RT) , which supports the analysis of coupled heat and fluid flow as encountered in a building andlor plant environment. The use of the system, and the design benefits to accrue, are demonstrated by elaborating two real world case studies.