numerical modelling

An earth-to-air pipe type heat exchanger (EAHE) is a simple and effective ventilation system component, used for preconditioning of the fresh air supplied to a building. This paper presents two sets of results of operational parameters long-term measurements and energy analysis of EAHEs, located under two different retail buildings of floor area over 1000 square meters each.  

As a part of the development of a numerical method of close capture exhaust systems for machining devices, a test rig recreating a situation similar to a grinding operation, but in a perfectly controlled environment, was produced. The properties of the obtained spray of solid particles were initially characterized using particle tracking velocimetry (PTV), in order to obtain input and validation parameters for numerical simulations. The dispersion of a tracer gas (SF6), emitted simultaneously with the particle jet, was then studied experimentally.

The distribution of the humidity in a dwelling unit is the key factor determining the condensationrisk and the mold growth, as well as the dryness problem. As the first stage of the research project aiming at the understanding and the solutions of the above problems, the experiment on humidity distribution in multiple rooms with the simulated occupancy was carried out in a full-scale research house. The effects on the humidity distribution of the ventilation, etc. are described and compared with the numerical predictions.

This paper deals with the study of natural ventilation in a building under tropical climates. Roomair distribution is analyzed with a statistical approach. The building is a cube with two opposing outdoor large openings. The cube is modeled using the RNG k-e model. A dimensionless velocity coefficient for different wind directions is evaluated for each indoor cell of the grid. Cumulative distribution function of this coefficient is calculated at different height to point out the influence of the wind direction.

A modified 65MN(Multi-Nodes) thermoregulation model is tested for the evaluation of the skin surfacetemperature distributions in each body part under solar radiation. The present model can be also applicable for the coupled analysis of CFD and radiation. Skin surface temperatures predicted by this model are compared with those by subjective experiments in the real scale experimental atrium under solar radiation. Predicted each skin surface temperature almost corresponds to that of subjective experiment with the accuracy around 1 degree Celsius difference.

This paper describes a study on the performance evaluation of a hybrid ventilation systemwith a heat exchanger. This system has two passive stacks and a heat exchange unit, which includes a heat exchange element, a supply fan, an exhaust fan and a bypass route with a damper. In order to evaluate the system performance, the experiments and numerical simulations using a full-scale test house have been performed in winter or mild seasons. In the result, the ventilation rate and the heat recovery rate under the various conditions of the fan and the damper operation were clear.

Airflow through openings in a cross ventilated building scale model was investigated in a windtunnel and by numerical predictions. Predictions for a wind direction perpendicular to the building showed an airflow pattern consisting of streamlines entering the room, that originated from approximately the same upstream area in the undisturbed boundary layer and a direction of the flow into the room dependent on opening location with velocity vectors pointing away from the stagnation point.

In this paper, an example of how to use the dynamic building and system simulation to design, determine and optimize the characteristics of a heating and cooling system of a school building in southern Germany, is presented.

This paper is a description of the design process of a new generation low noise axial fan. The emphasis is on the practical use of acoustic knowledge issued from published work and engineer know-how. The use of date issued from numerical simulation is also presented.

A numerical investigation has been made on the effect of thermal and mass buoyancy forces on the development of laminar mixed convection between vertical parallel plates with uniform wall heat and mass fluxes. Some parameters such as velocity, temperature and concentration are presented and their incidence on heat and mass transfer between the plates is discussed for both positive and negative values of the buoyancy ratio. Results and discussions are presented.