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Investigating Instantaneous Wind-Driven Infiltration Rates using the CO2 Concentration Decay Method

Carbon dioxide has already been recognized as a potential tracer gas for estimating the mean air exchange rates of a room or building. The wind direction and mean wind velocity have also been identified as critical factors that affect the air infiltration. In this paper, the indoor CO2 concentration has been logged at three specific points in an office room for seven selected measurement-periods. The decay method was used to estimate the infiltration rates (ac/h).

Uncertainties in Air Exchange using Continuous-Injection, Long-Term Sampling Tracer-Gas Methods

The PerFluorocarbon Tracer (PFT) method is a low-cost approach commonly used for measuring air exchange in buildings using tracer gases. It is a specific application of the more general Continuous-Injection, Long-Term Sampling (CILTS) method. The technique is widely used but there has been little work on understanding the uncertainties (both precision and bias) associated with its use, particularly given that it is typically deployed by untrained or lightly trained people to minimize experimental costs.

On investigating instantaneous wind-driven infiltration rates using CO2 decay method

Carbon dioxide has been already recognized as a potential tracer gas towards estimation of the mean air exchange rates (ACH) of a room or building. The wind direction and mean wind velocity have been also clarified as critical factors that affect the air infiltration. In this study, the indoor CO2 concentration is detected and logged at three specific points in an office room for seven selected measurement-periods. The decay method is used to estimate the leakage rates.

The measurement of air infiltration rates in large enclosures and buildings.

The report discusses the need for a proven method of measuring air infiltration rates in large enclosures in order to assess the need for and effectiveness of energy saving measures. The object of the research is to develop such a proven method. Some

Comparison of different airtightness and air exchange rate measurements in very small test building

The airtightness of the building envelope was studied in field measurements in recently constructed experimental small test buildings. Two types of research studies were carried out: the effect of special air tight sealing and the experimental determination of air exchange rate (h-1) under real operating conditions. In very small buildings with many joints between materials and construction the role of the air tight sealing is very important; the experiments show changes in measured air tightness.

Experimental study of diffuse ceiling ventilation in a classroom

Diffuse ceiling ventilation is a novel air distribution device that combines the suspended acoustic ceiling with ventilation supply. A diffuse ceiling distributes the supply air above the acoustic tiles and has proven performance in laboratory experiments. To study the performance in real conditions a classroom was retrofitted with mechanical ventilation and a diffuse ceiling. The employed ceiling comprises active panels penetrable to air and impenetrable passive panels.

Simple error reduction in tracer-gas field-measurements of air handling units

Tracer gas measurements are an unparalleled means of measuring air recirculation, leakage, and air flow rates in air handling systems [1-5]. However, such measurements are subject to significant measurement uncertainty in field conditions. A common problem is imperfect mixing of tracer gas.

Measurements and Numerical Simulation of the Gas-Solid Flow Generated by Machining Operation

As a part of the development of a numerical method of close capture exhaust systems for machining devices, a test rig recreating a situation similar to a grinding operation, but in a perfectly controlled environment, was produced. The properties of the obtained spray of solid particles were initially characterized using particle tracking velocimetry (PTV), in order to obtain input and validation parameters for numerical simulations. The dispersion of a tracer gas (SF6), emitted simultaneously with the particle jet, was then studied experimentally.

Investigation of the Parameters that Influence the Effectiveness of an Open Fronted Enclosure

Open fronted ventilated enclosures are commonly used in industry to control worker exposure to a wide range of chemicals. These enclosures tend to be of basic design and often consist of nothing more than a box like structure with an open front to allow worker access and extraction at the rear to remove contaminated air. This design forces the worker to stand at the face of the enclosure and by doing so presents a blockage to the airflow.

Evaluation of Indoor Air Quality in Classrooms Equipped with Cross-Flow Ventilation

In this work the evaluation of indoor air quality in a classroom equipped with cross-flow ventilation is presented. A numerical methodology, based on comparison with experimental data, used in the evaluation of the air exchange rate, airflow rate and the age of the air, was applied in the first phase of this work. The evolution of carbon dioxide inside spaces, with different airflow typologies, was then predicted in the second part. The study was based on a school located in the South of Portugal. In the experimental methodology the tracer gas decay method was applied.

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