Discussions Of Determination Method Of Fresh Air Volume To Control Typical Pollutants In Office Buildings

In recent years, with people's standard of living rising steadily, people's requirements of the service level of buildings have also been heightened. People are not only satisfied with the least functional requirements such as keeping out wind and rain, but also give more sight to the indoor air quality (IAQ). The importance and urgency has been recognized to address the issue to indoor air quality. IAQ problem has now become a hotspot in the area of building environment.With indoor pollution getting worse, people have to turn our gaze to air conditioning. At present, the air-conditioning system tends to focus only on the indoor heat and moisture environment, but considers very little to the indoor air quality factors. This article studies from the indoor air quality perspective. Indoor typical pollutants are studied, and determination metrod of fresh air volume to control the pollutants is discussed. Thereby we can achieve the purpose of truly improving indoor air quality. As there is a big difference in different kinds of buildings, this article is only researching the typical office buildings.First, the paper puts forward the concept of indoor air quality load, and points out the close relationship between indoor air quality and indoor pollutants, that is, the concentration of pollutants has to meet a reasonable standard, the establishment of which needs to consider objective and subjective elements. CO2 and HCHO are selected as typical pollutants in office buildings, evaluation method of logarithm index is adopted as evaluation method of indoor air quality, and new concentration standards of typical pollutants and CO2 of HCHO are established. The paper also establishes the standards to different dissatisfaction degrees which are to be chosen by designers according to specific situations.Currently, there are very few measured values of pollutants concentration. Only a few scholars have measured. In order to obtain first-hand information to calculate the weight of pollutants, and also to get more measured values as reference, the paper does a certain scale of survey. The specific contents include the theoretical basis, the survey program design, test and the analysis of results, formal investigation and the analysis of results, etc. The survey gets a certain amount of data. Analysising and processing these data will make more detailed understanding of specific data of the various office buildings, which will be useful to future design work.The paper analyses airflow organizing mode, and selects displacement ventilation as a reasonable mode of ventilation. The determination of the quantity of fresh air for mixed ventilation and displacement ventilation is given and checked. Then the paper deduces a direct calculation of the new wind ratio, which leaves out the complex process that the quantity of fresh air is calculated first and checked then. An example is given to introduce the specific process of designing and analysing a displacement ventilation system to control typical pollutants in office buildings.Finally, the CFD numerical simulation is done to validate the case of displacement ventilation. By examining the indoor concentration distribution of pollutants, we can see that the concentration satisfies the scheduled standard, that is, the quantity of fresh air meets the requirement. In addition, the analysis of air velocity and temperature field verifies that the simulation results are well consistent with the calculated results in the case.