tracer gas

The mixing of a tracer gas with zonal air was compared between two zones in an unoccupied test building in both the horizontal and vertical direction. A constant injection of sulphur hexafluoride (SF6) tracer gas was released into each zone separately and its concentration was measured at different positions within the zone. Variations in concentration were observed for different horizontal positions in the southern zone indicating incomplete mixing.

Measurements were performed in a test room at SINTEF building and infrastructure, Oslo. The test room is 16 m2 and built according to NS-EN 442-2.  Measurements of various air flow rates (9 l/s, 18 l/s, 34 l/s and 50 l/s) and different supply air temperatures (2, 4, 6 and 10 degrees over room temperature) were performed. Tracer gas (SF6) measurements were performed to evaluate ventilation effectiveness and age of air in occupied zone.

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).

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.

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 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

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.

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.

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.

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.