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.
Ships are very demanding on the ventilation systems that need to be installed. The reasons forthis are manifold. The following paper will address the problems around the ventilation layout for a typical RoRo-Ferry and will show how CFD can help the designers to optimize the system. One new area of interest is the simulation of fire to optimize the fire suppression systems in engine rooms of RORO vessels.
The paper presents experiment results of emission rates of HCHO from Medium DensityFiberboard (MDF, JIS grade E2) using three different test chambers. In this study, a full-scale stainless steel test chamber (19.68m3), a boundary layer type small test chamber (0.4m3), and a field and laboratory emission cell (FLEC, 3.510-5m3) were used. The coefficient of air change performance within the three test chambers was examined by CFD analysis. The convective mass transfer coefficient of HCHO from MDF was computed by CFD and the emission experiment.
For underfloor air distribution (UFAD) systems, more rapid mixing of the supply air with ambient airis desirable for better thermal comfort, and swirling air diffusers are usually used. In order to rigorously simulate the flow characteristics of such diffusers, we used the multi-grid technique and validated it with experimental results. In this paper, the technique is used to compare the square diffuser and the swirling diffuser.
The mean velocity in rooms predicted by CFD simulations based on RANS equations differs from the mean (in time) magnitude of the velocity, i.e. the mean speed, in rooms measured by low velocity thermal anemometers with omnidirectional sensor. This discrepancy results in incorrect thermal comfort assessment by the CFD predictions as well as incorrect validation of the predicted velocity field. In this paper the discrepancies are discussed and identified, and a method for estimating the mean speed based on the CFD predictions of mean velocity and kinetic turbulence energy is suggested.
Airflow characteristics in the air-conditioned spaces play an important role to obtain the comfortable and hygienic conditions. This paper utilizes a 3D time dependent Computational Fluid Dynamics (CFD) model to assess the airflow characteristics in four different air-conditioned spaces. It was found that the location of the air extraction port represents a critical design factor and would have a direct effect on the heat removal efficiency and the energy efficiency of the air-conditioning system from the airside wise.
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.
Within the last years CFD has become an essential tool to investigate and optimize concepts of train coaches during an early design stage to achieve best results without major modifications of the final design. The simulation of the current railroad double deck coach gives some special challenges because of the complex channel system and the different boundary conditions on each floor. First the air duct including the outlet vents is investigated and optimized. The results are used as boundary condition for the simulation of the passenger's compartment.
Fläkt Woods, which manufactures a wide range of ventilation equipment, has undertaken a programme of experimental verification of the concepts of new displacement ventilation equipment, as well as validation of a CFD (Computational Fluid Dynamics) package
This paper analyses an individual control system that accounts for human thermal adaptation.Although the conventional individual control system has been shown to provide a satisfactory level of thermal comfort, there are questions over its energy efficiency. It has therefore become urgent to develop a new individual control system that can ensure both energy saving and thermal comfort. In this study, the alleviation time is proposed as an energy-saving control strategy for the individual control system.
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