When designing natural ventilation for complex buildings, it is key to understand whether there is a unique solution for the flow, or if multiple flow regimes are possible. Here, we show that in a 2 storey open plan office type building, in which the floors are connected to a common atrium, two stable flow regimes may occur under identical conditions.
The aiflows driven by a revolving door that links two rooms of initially uniform temperature are examined. Two situations are considered, the first in which the rooms are at equal temperature, and the second in which there is a temperature difference between the rooms.
The flows were examined using a small-scale model of a revolving door and with fresh- and
salt-water solutions to represent temperature differences. The results presented herein reveal
how the transfer of air across a revolving doorway depends on the rotation rate and temperature
As part of an investigation into single-sided natural ventilation, a computational fluid dynamics study was performed to analyse the impact on the airflow rate of the dimensions and position of a large rectangular opening and of the temperature difference between inside and outside air. An empty room with a rectangu-lar opening in the external wall was assumed and the Bernoulli formula used to calculate discharge coefficients Cd. The vertical position of the opening was found to have the greatest impact on the discharge coefficient.
The fluctuating characteristics of airflow have impacts on the thermal comfort of people. Two kinds of mechanical airflows in indoor environment were tested and analyzed in the paper. Spectrum analysis, chaos analysis were used to study the rule of the fluctuating characteristics shifting of the mechanical airflows. The results show that the fluctuating characteristics of different kinds of mechanical winds are different. It is also found that the characteristic parameters of the mechanical airflow, such as power spectrum etc.
The air exchange rate is a determinant factor for the indor air quality in a given spaces. If it is lower than the required it may cause the so caled sick building syndrome. The ultimate result depends, obviously, also on the nature and strength of the sources emisions. In this work the natural
Within the European project - Friendly Heating - a local heating system is designed. The main goal is not to heat the monumental churches themselves, in order to prevent damage to valuable art works and the building itself. The idea is to provide a thermal comfort zone for the people in the pew using radiant heat sources. Measurements in a climate room are used to a) evaluate the local climate created by the bench heating system and b) evaluate the CFD model. The results will be used in ongoing research on the prediction of the indoor climate in a church under real climate conditions.
Rising energy prices have contributed to the development of heat pump-based heating systems in Sweden. Low flow temperature in the secondary heat distribution system to rooms is a requirement for energy-efficient systems. This increases the thermal efficiency of the heat pump and decreases thermal losses in the distribution system. Flow temperatures in water-based systems for heat distribution in buildings have been decreased from 55C to temperatures around 30C. This is to maximize the efficiency of heating systems that are based on heat pump technology.
This research was to assess the performance of air infiltration, the corresponding energy consumption, indoor contaminant level for residential buildings in Harbin, a typical city in the severe cold region of China. Based on questionnaire survey and field measurements, the prototypical apartment building includes its physical structure, air leakage and life style of occupants has been determined. Then unsteady-state numerical simulations were carried out by the use of COMIS.
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.
We conducted an on-site test of air-conditioning systems in a hotel in Changsha, Hunan, China in the summer of 2003. And indoor particulate matters, bioaerosols were the main pollutants sampled from indoor spaces and three air-conditioning systems, one of which serves the lobby of the hotel, with the other two supply fresh air to the cook room and dinning-rooms. Short-term and long-term sampling of deposited particles in the air-conditioning systems was carried out and their size distribution was tested by Optical Particle Counters (OPCs).
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