The occupants of buildings are exposed to a range of aerosol contaminants, of both indoor and outdoor origin; at present, filtered mechanical ventilation is the only effective means of airborne particulate control in polluted urban areas. Significant energy costs may be incurred, however, through the large pressure drops associated with membrane filtration. An alternative to filtration might be the enhancement of aerosol deposition on a protruding surface which is parallel to the incoming airflow direction, but which does not significantly retard the airflow.
Today, laws and regulations play a major role in just about everything we do. The declining quality of the air in our buildings is causing movement towards regulations relating to how buildings should be designed and operated. It is important that designers and operators are aware of all current design and operating standards. ASHRAE Standard 62, "Ventilation for Acceptable Indoor Air Quality" developed in l 989 and now under revision, has created new challenges for designers and engineers.
The air distribution effects of floor mounted swirl diffusers are investigated and described inthis paper. Results are based on a case study of an office typical of those in urban commercialenvironments. The effects of the swirl applied to the supply air as well as temperaturedifferentials between supply and room air are explored. The investigation is restricted tosituations where cooling is required.The results of the work, which is undertaken by way of CFD analysis, are presented in termsof appropriate ventilation effectiveness parameters.
Until now, there is no widely accepted way to express any index for this purpose and taking into account the large variety of possible pollutants. Things can be simplified if the aim is to compare different systems and strategies rather than to give an absolute value of quality. For the study of a pollutant source, the main important point for comparison is the pattern of its production, whatever this pollutant is. The detailed data for each inhabitant is the curve of the number of hours above a pollutant level concentration Ci: Nh (Ci).
The paper deals with a research about analytical techniques for meaningful, reliable, cost-effective, in-situ, real-time and continues determination of airborne chemicals, by means of a new electrochemical sensor; the research aims to develop objective instrumental sensing systems able to substitute the subjective human responses. Sensor detection capability could regard a series of analytes: carbon dioxide, carbon monoxide, inorganic pollutants, ammonia and other metabolic gases, irritants, odours.
Assessing the perceived air quality in decipols by trained panels can be performed rather perfectly today. To calculate the olf load from these results is a little more problematic as one requires olf loads which can simply be added (linearly). The reason for this difficulty is the nonlinear relation between the perceived air quality in decipol and the pollution load in olf. The relation can be expressed by an exponential function in a range between l to 15 decipols. Unfortunately the exponent and the constant in the exponential function differ for different substances.
This paper considers methodologies how desired level, target level, of industrial air quality can be defined taking into account a feasibility issue. The method is based on the health-based risk assessment and the technology-based approach. Because health-based risk estimates at low contaminant concentration regions are rather inaccurate, the technology-based approach is emphasized. The technological approach is based on information on the prevailing contaminant concentrations in industrial work environment and the benchmark air quality attained with the best achievable control technology.
The purpose of this paper is to evaluate the performance of 4 kinds of ventilation systems from the point of view of indoor air pollution and energy need during heating season under Japanese conditions by numerical simulation. TVOC was selected to characterize the indoor air quality impact to residents. The results show that in the case of mechanical exhaust ventilation system, TVOC level is the highest among all the systems. Mechanical central supply and exhaust ventilaton system shows its advantages for minimizing energy consumption and maintaining an acceptable indoor air quality.
Login