This paper presents the field experiments on the ventilation efficiency in an underground car park where high velocity fan-diffuser units were installed as shown in Photo 1. The concentration of SF6 were measured as tracer gas under the step up condition and the step down condition, and the ventilation efficiency such as the age of air were calculated from the rising curve and the falling curve of the SF6 concentration in the underground car park. The ventilation efficiencies of two cases were compared, i.e.
This paper presents the results of the numerical simulation on the ventilation efficiency and the residual age of air by using CFD in the underground car park in which the field measurement was conducted as shown in a previous paper. The agreement between the CFD result and the measurement one was observed at most of the measuring points. The detailed distribution of local air change effectiveness was examined with the results from CPD in this paper.
The ventilation efficiency in a displacement ventilated room with non-buoyant pollutant sources was evaluated under laboratory conditions. The contaminant removal effectiveness was measured for different positions of the pollutant sources and with different ventilation flow rates. The air change efficiency and the temperature gradient in the room was measured for the different ventilation flow rates. The contaminant removal effectiveness was much dependent on the position of the sources and varied from 30 to 240 %.
This paper discusses the application of a new strategy approach for the room air conditioning. The basis of the classification is different aims or ideas of the temperature, gas, particle, humidity distributions and room air flow patterns that can be created within a room. A certain strategy can be applied by using different system combinations of room air distribution, exhaust, heating and cooling methods and their control. The realization of an ideal strategy is also dependent on the operating parameters and internal sources.
Ventilation system has to be design in order to strike a balance between indoor air quality and energy requirements.So, the ventilation efficiency can be considered as a major issue to deal with this objective. In order to assess the efficiency of pollutant elimination from a room, a methodological approach using CPD has been developed. It is based both on local and global indexes. These indexes take into account the distribution of pollutant concentration inside room and the mean concentration at the exhaust with respect to the occupant location.
The present study deals with indoor air quality and is mainly based on an experimental work. The experimental set up is a full scale test cell with a ventilation system which comprises a fixed air supply and a mobile extract. A source of pollutant continuously supplies tracer gas at the centre of the cell. We carried out 12 tests under steady state and with various conditions. The test parameters were the exhaust location, the fresh air now rate and the supply air temperature.