The proposed local dynamic similarity model can select an adequate discharge coefficient to match the approaching flow angle. This is an improvement over the conventional orifice flow model where the discharge coefficient is set to a fixed value. The accuracy of predicting ventilation flow rates for an isolated cross-ventilation model is greatly improved when the discharge coefficients actually decrease with change of wind direction.
The effect of draughts on the steady thermal stratification established by a localised heat sourceat floor level in a naturally ventilated enclosure with upper and lower openings is considered. Ourexperimental observations in water using models indicate that four different steady flow patterns arepossible depending on the relative areas of the upper and lower openings.
We performed numerical simulation of the inflow characteristics at an opening by using LES,the standard k- emodel, and the improved k- emodel that was applied Durbins limitation (hereafter, it is described as Durbins k- emodel in this paper). As a result of this simulation, Durbins k- emodelreproduced the experiment result fairly well as in case of LES. Accordingly, by using Durbins k- emodel, the analysis was carried out on the air flow characteristics at some openings. As a result, the static pressure increase was induced by the collision of the air flow with the leeward opening frame.
Pressure loss mechanism at the inflow opening of Cross-Ventilation is studied by detailed analysis of LES results. Manipulation of energy transfer equation through inflow openings suggests that reduction of discharge coefficient should be originated from dynamic pressure in tangential direction and should be observed as increased static pressure at the opening.
The sick house syndrome has become a serious problem in Japan recently. It is important tospecify and quantify the source of chemical pollution. In this study, passive samplers for concentration of chemical substances in the air, ADSEC for emission rate of chemical substances from building materials and PFT method for ventilation rate in a room were developed. These passive methods enable investigation of many houses at a time. Indoor air quality of a newly built house was measured by these passive methods in summer and winter.
This study describes an experiment on a Task Unit and reports the results. The Task Unit coolsthe upper half of the body by isothermal air flow and warms the lower half of the body by a radiant panel. Tests were designed to compare heat removal by moving air after identifying the metabolic rate and how the thermal sensation and comfort sensation improve during the summer season. As a result, when the room temperature rises, the activity ratio of the Task Unit rises, too.
This research proposes a method for task area wide-cover personal air conditioning thatprevents a human body in the task area from being exposed to a largely irregular thermal environment. A Particle Image Velocimeter (PIV) was used in the research to measure air flow fields for conventional spot cooling and wide-cover personal air-conditioning(PAC) around the human body. The wide-cover type PAC formed a calm air flow field of less than 0.18m/s around the human body, while the spot cooling type PAC formed an air current of 0.3-0.6m/s around the area of the neck.
This study presents the results obtained when Computational Fluid Dynamics is applied tocalculating the flow in a domestic kitchen hood at operating conditions. Special emphasis has been placed on parametric modeling of the geometry to permit the rapid modification of fundamental parameters, such as the number of blades and the twisting angle. The governing equations (mass, momentum, energy and turbulence) have been solved using the commercial code, Fluent.
The present paper evaluates indoor thermal environment, cooling efficiency and energy consumption between a floor-based system and a ceiling-based system using a mock-up model in cooling period. The experimental chamber has a UFAC, underfloor air conditioning system and a ceiling-based system. And the experiments are set with practical internal load conditions including occupants, lighting units, and heat sources (office automation equipment). The following were compared and evaluated;
1) the vertical and horizontal temperature distribution,
The microbiological quality of air was studied in a bread-making factory (100t/day). It wasnoticed that the microorganism density varies along the fabrication hall, a high number of microorganisms, especially moulds, being registered in the bread cooling area and the storage room. In the bread cooling area predominate Penicilllium expansum spores, this mould being able to develop at low aw values and determining the bread spoilage.