The selection and design of air conditioning systems in Hungary are based on a determined modelling state. In the last decade this was a safe enough basis for the management of systems. As a result of the changes in the macroclimate, however, there has been a major increase in summer temperatures. Taking into account this fact and the need to develop the earlier deterministic modelling techniques we chose to focus on risk-based modelling.

This paper reports the results of room model experiments and Computational Fluid Dynamics(CFD) analysis of ozone distribution in indoor air. The analyzed room model had one supply inlet and one exhaust outlet, with a cavity of dimensions 1.5m (x) 0.3m (y) 1.0m (z) in which a two-dimensional flow field was developed. In order to discuss the order of wall surface deposition for ozone, the concentration distributions of ozone in the model room were measured. CFD analysis corresponding to the experimental conditions and with a built-in ozone wall surface deposition model was carried out.

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.

This paper presents an exploratory study on flow pattern selection in unmixed flows, resulting in aset of rules that are used to decide between flow regime during and before a simulation. The development of this set of decision rules had several goals: to define simple criteria to distinguish between flows, to assist non-expert users in the selection of the correct flow pattern model and finally to automate the choice of models during numerical simulations in energy simulation software.

This paper presents a simple model for vertical temperature profile and heat transfer predictionin displacement ventilation. The fully-mixed room air approximation that is currently used in most whole building analysis tools is extended to a three node approach, with the purpose of obtaining a first order precision model for displacement ventilation systems. The use of three nodes allows for improved prediction of thermal comfort and overall building energy performance in low energy cooling strategies that make use of unmixed stratified ventilation flows.

The purpose of the present work is to describe the ability of the advanced computer packages(CFD codes) to perform numerical simulations of general refrigeration engineering problems. The case study concerns the modelling of three-dimensional turbulent airflow with thermal buoyant effects and air temperature distribution in the refrigerated compartment of a perishable foodstuff transportation vehicle.The numerical predictions obtained with three commercial codes (PHOENICS, FLUENT and CFX) and an academic one are evaluated and compared with experimental data.

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.

This article describes CFD simulation results and measurements using a swirl diffuser. Thediffuser is able to provide relatively low velocities within the occupied zone while supplying high airflow rates. The flow pattern produced by the air diffuser was validated by measurements with a flow rate of 133 l/s and 4 C lower temperature than ambient air. Turbulence was modelled using the RNG k- e model with additional swirl modification.

This paper describes a comparison between internal and external run-time coupling of CFD and building energy simulation software. Internal coupling can be seen as the traditional way of developing software, i.e. the capabilities of existing software are expanded by merging codes. With external coupling, two or more software packages run simultaneously while exchanging calculation results at appropriate time intervals.

This paper outlines the extension of a CFD model using DBM modelling approach. Primarily adynamic CFD model is proposed for adiabatic ventilation system. At the inlet a step rise in temperature of the incoming air with steady flow rate is used for the CFD simulation and temperature responses at 36 monitoring locations were extracted. In the second stage, the inlet and the extracted temperature profiles were used to develop DBM models at individual locations. Finally the developed compact DBM model was used to construct model based predictive control algorithm.