Numerical Simulation Research Of Thermal Environment And Nuclide Pollution Control Under Stratified Air Conditioning In High And Large Factory Building

In general,stratified air conditioning was used as an energy saving air-conditioning technology in the large space workshop of the nuclear industry,and nuclear aerosols produced in process production were mainly captured and removed through exhaust hoods.When the local exhaust system is operating under abnormal conditions,the local exhaust air volume was lower than the air volume for catching dust,and the nuclear aerosol emitted from the process position was susceptible to migration and diffusion due to the influence of stratified air-conditioning airflow organization,which posed a potential radiation hazard to workers.In this paper,under the conditions of two types of stratified air conditioning air flow,namely,"unilateral medium delivery,opposite-side next-return" and "bilateral delivery and next-to-near return",a large space factory building in the nuclear industry was taken as research object,and the indoor thermal environment and the law of radionuclide aerosol transport were numerically simulated by using the FLUENT software.The research conclusions can provide guidance for the design optimization of the stratified air-conditioning and local exhaust systems and the layout of the work area in the nuclear industry.The research content mainly includes the following aspects:1)Based on the production demand,two kinds of stratified airconditioning airflow organization schemes were designed,and the numerical models and boundary conditions were verified by the measured data,and the boundary conditions of high precision numerical simulation were realized.2)Based on the numerical simulation of indoor thermal environment of high and large factory building,the thermal environment of working area was evaluated by introducing "thermal comfort index",and the influence of different heat source distribution position on indoor thermal environment also be compared and analyzed.Besides,the merits and demerits of the thermal environment in the working area of two stratified air conditioning airflow were discussed,and the rational heat source layout form was obtained.3)Based on the numerical simulation of the migration and diffusion of nuclear aerosol of high and large factory building,the radiation concentration in the working area was evaluated by introducing the nuclide "derived air concentration index(DAC)",and the effects of different radionuclide aerosol emission positions,different local exhaust velocity and height on the migration of aerosol also be compared and analyzed.Besides,the reasonable layout of pollution source was obtained,and the proposal for optimal design of local exhaust air was put forward.4)Based on the comparative analysis of the migration of nuclide aerosol under the condition of two kinds of stratified air conditioning air distribution,the design proposal of stratified air conditioning and local exhaust was provided.