This paper presents an analysis of different possibilities of representing mass transfers in zonal models. In this aim, formulations derived from the Navier-Stokes equations or from Euler's theorem are obtained. The models which result from them and empirical models are compared so that to define the best compromise between simplicity, accuracy and easy convergence.
The series connected heat exchangers - configured either as an arrangement of gas-gas,gas-liquid or liquid-liquid heat exchangers- are widely used in the process industry andair-conditioning where they can be found in a variety of heat (cool) recovery, in heating andcooling applications.
The purpose of this research is to give an overall prospect of the performance of 4 kinds of ventilation systems for dwellings using numerical simulation under various conditions. The total number of combinations of various parameters for the calculation is 174. Calculations for pollutant concentration, humidity and condensation, interior pressure and airflow rate, heat energy by ventilation, etc. are performed hourly through the heating season.
This paper deals with the interzonal air movement in a building, throughhorizontal openings, under natural convective conditions. These airflow phenomena areinvestigated experimentally, through a series of experiments in the stairwell of a full-scalebuilding, using tracer gas technique. The resulting time-dependent concentration evolutionoffers a means of analyzing the flow field. These cases are also simulated by a CFD code, thatuses the finite-volume method and incorporates a low-Reynolds k-E two equation turbulencemodel.
This paper will present a general approach that may be used to solve natural ventilation designproblems typically addressed at the preliminary design stage - How wide should windows beopened in a given building for wind-driven cross ventilation on a moderate summer day? Howshould a ventilating monitor be configured to mitigate internal and solar gains on the samesummer day?
Evaporative cooling is an interesting alternative to conventional compressor refigerationsystems for air-conditioning. However, the use of evaporative cooling presupposes all-airsystems and is, to a large extent, limited by ambient conditions as well as the settled demandson the indoor climate. High outdoor humidity levels have a great influence on the supply-airtemperature achievable, i.e. cooling loads possible to meet. One way to reduce the influenceof these limitations is to use desiccant cooling, i.e. to dehumidify the ambient air before theevaporative stages.
In the present paper a model for steady-state thermal analysis of ventilated and unventilated light rook is proposed. The aim of the work is tostudy the influence of thermo-physical and geometric parameters of the roof and boundary conditions (solar radiation) on the entering heat flowand the temperature distribution within the roof structure.
In this paper the potential of night ventilation techniques is investigated. Extended real scalemeasurements have been performed, in three buildings, under free floating and airconditioned operation. Two of the buildings have been studied by using a theoretical modeldeveloped in TRNSYS [1] software. Simulation results have been validated by using themeasured data. Specific studies concerning the indoor air temperature and the cooling load ofthe buildings have been carried out in order to identifj the influence of night ventilationtechniques on the buildings thermal performance.
In France, mechanical cooling is increasingly used in office buildings. This situation isrelated to a demand for a better comfort, the increase of the thermal insulation and internalgains, and the changes in the building design.Nevertheless, in many cases, it is possible to achieve a thermally comfortable environmentby passive means - as thermal inertia, and solar protection of the external envelope - and useof low energy techniques as night or evaporative cooling.
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