A ventilated cavity wall is often proposed in the building envelope design as an alternative to thetraditional wall, mostly due to its ability in reducing the thermal load during the hot season. In order to be recommended as a solution for improving the thermal comfort, a thorough analysis of its performance under all possible scenarios is required. For assessing the thermal performance of the cavity wall, an experimental model has been built and tested at the DECivil of IST.
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.
We consider the overnight evolution of an initial two-layer thermal stratification (a warmupper layer and a cooler lower layer) in an enclosure ventilated via openings at high and low levels.Results of our laboratory experiments show that an efficient displacement flow is not always established and four distinct ventilation flow regimes are observed depending on the ratio R (= at /ab ) of the upper opening area, at , and lower opening area, ab ( > 0). For a given initial stratification, displacement flow is established only if R is sufficiently small (i.e. at
One of the main arguments supporting the application of the natural ventilation is the reduction inenergy consumption and capacity of the HVAC system. Here several tests of the building with different systems are carried to quantify the differences in capacities and energy consumptions of different solutions for the HVAC system. The tests were carried with the simulation program built in Simulink. To validate the model the measurements were done in Test cell at TU Delft as well as in the real office building.
Experiments were carried out to study transition phenomena in buoyancy-induced natural ventilation in a relatively large-scale enclosure equipped with a localized heat source and two openings (upper and lower) on one of the sidewalls. The process studied is transition from the mixing to the displacement ventilation mode realized by opening the lower vent to different heights while keeping the upper vent fully open. Measurements included inside vertical temperature profiles and air velocity through the upper vent.
Multiple regression analysis is used to predict the mean room velocity and determine the most influencing parameters on the velocity. More than 120 experiments for four different heat source locations were carried out in a test chamber with high level mixing ventilation. The measured parameters, such as supply air momentum, room heat load, Archimedes number and local temperature ratio, were used as independent variables. These parameters are examined by two methods: a simple regression analysis incorporated into scatter matrix plots; and multiple stepwise regression analysis.
The paper presents experiment results of emission rates of HCHO from Medium DensityFiberboard (MDF, JIS grade E2) using three different test chambers. In this study, a full-scale stainless steel test chamber (19.68m3), a boundary layer type small test chamber (0.4m3), and a field and laboratory emission cell (FLEC, 3.510-5m3) were used. The coefficient of air change performance within the three test chambers was examined by CFD analysis. The convective mass transfer coefficient of HCHO from MDF was computed by CFD and the emission experiment.
The assessment of the overall thermal insulation of the air shear layer surrounding a nude humanoid shape, as affected by different step rates, is the main objective of the present study. Step rateswere controlled at 0, 20, 30 and 45 steps/min. The measurements were carried out in a climate chamber with an articulated thermal manikin of the Pernille type with 16 body segments. In addition, the convective heat transfer coefficients for the 16 segments and for the whole body were determined for each step rate.
Various air cleaning technologies and products are commercially available to remove VOCsfrom indoor environment. By conducting full-scale chamber tests, this paper compares theremoval characteristics for VOCs between three commercial portable room air cleaners,representing three major types of technology: sorption filtration, ultraviolet-photo-catalyticoxidation (UV-PCO) and ozone oxidation.
This paper presents the indoor air quality performance of a displacement ventilation system ina thermal chamber. This study consists of two sets of experiments. In the first experiment, thethermal chamber was operated under displacement ventilation (DV) mode with the relativehumidity (RH) set at about 65% while the ambient temperature (AT) at 1.3 m height variedfrom 22 to 26C. In the second experiment, all the conditions are the same except that theventilation strategy is changed to mixing ventilation (MV).