Carrying out tests on occupied buildings presents several challenges. Typical instrumentation that can be used in unoccupied test cells cannot be used in occupied spaces. We have videotaped the behavior of helium filled balloons to track the airflow patterns within the building. If the balloons closely follow the local average airflow behavior they will provide substantial insight. For neutrally buoyant balloons, the observed horizontal motions should provide an accurate picture of the corresponding air motions.
In this paper a new test room for thermofluidynamic measurements is presented. The tests have been realised in the Officine Volta (Italy) workrooms as result of a collaboration between researchers of the Department of Fisica Tecnica University of Rome La Sapienza and researchers of the Officine Volta society. The laboratory was thought exploiting the knowledge in the field of thermofluidynamic achieved by the department of Fisica Tecnica in the last few years.
Carbon dioxide exhaled by people can be used as a tracer gas for air change measurements in homes. Good mixing of tracer gas with room air is a necessary condition to obtain accurate results. However, the use of fans in dwellings to ensure mixing is inconvenient. The natural room distribution of metabolic CO2 was simulated in laboratory experiments and verified in a field study. The results of the field measurements presented in this paper support the findings of the laboratory study, i.e. that CO2 is well mixed into the room air even though fans were not used.
Tracer gas sorption in and permeation through building materials influence tracer gas ventilation measurements. The permeation of the commonly used tracer SF6 through three different building materials (gypsum board, wood particle board and MDF-board) with and without paint has been experimentally investigated. The results show that the tracer diffuse through untreated boards and that gypsum board has the largest permeability towards SF6. However, the diffusion rate of tracer is effectively reduced when the boards are coated with two layers of latex paint.
In this study, the houses located in the northern region of Japan had been investigated. The investigation included the measurement of the ventilation rate using four different methods, namely the constant concentration method, measurement of airflow at inlet/outlet and two kinds of PFT method. This paper shows the relationship between the measurement results of ventilation rate via these four measurement methods. It is found that the amount of outdoor air introduced is insufficient for many houses and some of the used ventilation systems are not properly operated.
Airborne particle concentrations of 20 nm to 10 µm particles were studied in two similar classrooms in a school. One classroom was ventilated by mixing ventilation with supply air filtration and one by displacement ventilation without supply air filtratio
We present a method capable of measuring the velocity field in a 7.00m x 3.50m plane of a large-scale Rayleigh-Bénard (RB) experiment using an adapted Particle Image Velocimetry (PIV) technique. The structure of the flow in RB convection is well known for
This paper shows the successful application of CFD simulations for analyzing complex room air flow problems in real applications and deriving optimized solutions.
For a specific thermal anemometer with omnidirectional velocity sensor the expanded total uncertainty in measured mean velocity Û(Vmean) and the expanded total uncertainty in measured turbulence intensity Û(Tu) due to different error sources are estimated
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