For exhaust systems that handle dusts, a minimum transport velocity is required to prevent settling and plugging of ductwork. The minimum transport velocity required was studied experimentally for different kinds of dusts. In the case of horizontal ducts, three different velocities related with the minimum transport velocity were measured: saltation velocity, settling velocity and pick up velocity. The experimental results obtained are shown in different graphs, plotting minimum transport velocities vs. particle size and density.
This paper critically reviews current and previous research into the use of displacement ventilation in commercial offices with and without supplementary static cooling devices. It also reports the findings of a preliminary study of a displacement ventilation technique that may increase the scope of application for displacemelllt ventilation systems without the need for supplementary static cooling.
A method was developed to estimate dust production and deposition rates for a ventilated airspace without a recirculation system under steady-state conditions. The method was derived from a dust mass balance equation and parameter estimation method. The measured variables required for using the method were the dust concentrations and ventilation rates of the ventilated space. The outputs of the method were dust production and deposition rates.
This report summarizes the findings of comparative field tests and analysis sponsored by the Govenor's Office of Energy Conservation in Colorado on production housing models using both fiberglass and cellulose Insulation materials. The participating company was McStaln Enterprises, a mid-size (250 homes/year) production builder based In Boulder Colorado. Field test coordination and energy analysis were conducted by SOCTECH (State of Colorado Technical Energy Consultants for Homebuilders) .
The majority of urban pollution is traffic related and often shows daily variations with peaks occurring at rush hours. Poor outdoor air quality can affect the IAQ of local buildings that ventilate with polluted air. This is particularly applicable to buildings where AHU air intakes are at low level and adjacent to busy roads. The effect of pollution peaks can be minimized by ventilation control and this paper presents potential control techniques for periods when outdoor air quality is poor.
There is increased interest in using chilled ceilings and beams for cooling in UK buildings, on account of their perceived advantages over traditional air or chilled water based systems. However, there is currently limited knowledge or experience of the use of chilled ceiling and beam systems in the UK, and there is no proper professional guidance. Designers are particularly concerned to avoid condensation occurring on the exposed cold surfaces that could cause a health problem or lead to the so-called "office rain" effect.
This paper discusses two complementary techniques for modeling human exposures to airborne contaminants with a focus on control decisions involving ventilation. Particular attention is given to: (I) the use of empirical-conceptual models with dimensional analysis and (2) computational fluid dynamic simulations. Both techniques provide valuable information. An empirical -conceptual model is formulated with dimensional analysis for a spray painting operation.
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