PR1999

This article briefly describes a research program undertaken by the National Institutes of Health Office of Research Services to investigate ventilation performance of different laboratory configurations, and their affect on the hood. It focuses on some specific recommendations identified by the work which should help designers optimise performance. The intent is to provide a basis for guidelines to maximise lab hood containment performance, while minimising the impact of the lab layout and ventilation system.

Scale model experiments give possibilities for analyses of the design conceptions of ventilation especially of air distribution in large enclosures. When simulating aerodynamic and thermal processes in scale models of room ventilation, the flow patterns are visualised and the air flow temperature and velocity are measured. The paper presents the results of experimental tests of the air mean velocity field in three different size models of the same ventilated room. The field maps of the air velocity mean value were analysed.

The purpose of this study was to evaluate the indoor air quality parameters in a residentialdwelling using information from the field. The subject was a typical example of the modernItalian dwelling stock, built in the 1980s in a residential area in the northernpart of Rome.The dwelling was constructed from pre-cast panels using industrial building techniques. Thewindows were steel-framed and painted. Airtightness was measured to obtain the ACH (airchanges per hour) at 50 Pa pressure difference, and ELA (equivalent leakage area).

The objective of this research is to investigate thermal comfort and air flow distribution insidea test room which is naturally ventilated. The test room is ventilated through adjustablelouvers. The air pressures and velocities across the openings together with indoor airtemperature and mean velocity at four locations and six different levels are measured. Thecollected data are used to predict thermal comfort parameters across the test room. Tests werecarried out over the winter and summer time.

An efficient numerical method for solving the Reynolds-Averaged Navier-Stokes (RANS)equations with turbulence models for complex geometry and high Reynolds number flows isused to perform a highly-resolved computation of the turbulent flow in a strongly curved partof a ventilation duct.The three-dimensional incompressible RANS equations and the isotropic k-w two-equationnear-wall turbulence closure are written in generalized curvilinear coordinates in the strongconservation form.

The Paper deals with numerical computations, carried out, in order to predict the effects of natural convection on the thermal performance of porous material. In this paper the effect of natural convection in a horizontal porous layer will be discussed. The study of the above configuration is essential to understand the functioning of insulation of the type used in attics. The influence of natural convection on the thermal properties of mineral wool, loose-fill insulation, insulation made of small and large polystyrene balls are studied.

The necessity to provide and maintain high cleanness of air in the rooms of the highestcleanliness classes requires a proper adaptation of selection and designing methods for airfilters. The level of air cleanliness for such rooms is defined numerically by the determinationof the permissible number of dust particles whose diameters are equal or higher than the givenlimit values.

Air flow patterns in rooms can roughly be classified as one of three types: Displacement flow, source flow and mixed flow. Displacement flow in its original meaning is only used in special applications like clean rooms. Mixed flow is generally found in air-conditioned spaces, source flow which is frequently also called "displacement flow" is the usual type of flow in naturally ventilated spaces. This type had become more and more common in air-conditioned spaces in recent years.

A secondary analysis of the Dutch prevalence study by Zweers et al shows that office buildingswithout artificial cooling and with operable windows have a lower risk for health symptoms andcomfort complaints than office buildings with artificial cooling and sealed windows. Temperature ,simulations of various office buildings show that in the Dutch climate zone thermal comfortduring summer conditions is secured without the use of artificial cooling if a number of essentialdesign criteria are met.

Split-system air conditioning is increasingly usedapplications, owing to its low cost and installationboth for residential and commercialease. The indoor split-system unit iscommonly of the wall-mounted type and, due to its dimensions and position, very often itgives rise to appreciable air velocities and temperature gradients in the occupied zone of theroom. This work reports and discusses some experimental data collected in a test room withwall-mounted indoor unit, under different operating conditions.