| The pharmaceutical industry is a significant industry that related to human health and life.In order to ensure the quality of medicines,machine should be product in a regulated environment and should formulate according to the laws in the industry.The strict requirements have been set on the cleanliness of the pharmaceutical production environment.The air-conditioning system should be further improved for meeting the requirement of standard.In addition,it is urged to explore effective methods which can reduce the risk of crossing contamination in specific zone.In this thesis,the airflow field and the cleanliness recovery characteristic in cleanroom are mainly investigated,and the approach of reducing the particle concentration and improving the cleanliness recovery characteristic are studied.Firstly,the basic framework of numerical simulation and typical experimental validation of pharmaceutical cleanroom will be established,which is the most important content of the research.The content include the validation of turbulence model,particle transport model and inlet model.Then,the characteristic of airflow in the 10.000 cleanroom are studied using CFD method.By studying the reference air change rate 15 h-1≤ACH≤25 h-1 in the specification,a total of 11 cases are studied to investigate the indoor local flow field and particle trajectory.The result show that the reference range can be divided into two zones:When 15 h-1≤ACH<20 h-1 and 20 h-1≤ACH≤25 h-1.The difference of indoor flow field distribution in each interval of air change frequency is small,but the difference of flow field between the two intervals is large.In addition,when the factors such as thermal comfort,fresh air attenuation and particle residence time are taken into consideration,the ventilation value of 22 h-1≤ACH≤23 h-1 is recommended according to the conclusions in this thesis.In order to theoretically study the effect of exhaust ratio on indoor flow field characteristics,six different exhaust ratios（0,0.2,0.4,0.6,0.8 and 1）are selected to obtain the local indoor flow field and the trajectory of particulate.Considering the thermal comfort,the attenuation of air supply,the removal efficiency of particle and the aggregation of particulate in the occupied zone,the exhaust ratio of 0.4 is recommended in this thesis.In some cases,the occupied zone and the unoccupied zone are clearly divided,so the approach of increasing the airflow rate of the occupied zone and reducing that of the unoccupied zone（changing the ratio of the air supply from working area and non-working area）is proposed,and this method is validated by numerical model.It is found that for the air change rate ACH≤19 h-1,the ratio of airflow rate between the unoccupied zone and the occupied zone can be adjusted to 1:2 or 1:3.If the ACH≥19 h-1,there is no need to deliberately increase the air supply volume of the occupied zone.Increasing the airflow rate of the occupied zone cannot effectively improve the pollutant removal efficiency,and even has the opposite effect of reducing the removal efficiency.In order to take the above conclusions as the theoretical guidance of engineering practice,the thesis gives a suggestion table for parameter selection when indoor demand is different.Finally,the influence of the indoor concentration that after the production operation is completed,on the indoor cleanliness recovery characteristic is studied.And the statistical method of orthogonal experiment is used to analyze the significant factors affecting the cleanliness recovery characteristic. |
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