Simulation Study On Airflow Distribution Of Radiation Cooling Plus Fresh Air System Of Common Functional Rooms In Civil Building

With the widespread use of air conditioning systems,the demand for energy is increasing day by day.However,traditional air conditioning systems have many disadvantages,such as wasting energy,low heat exchange efficiency,and high air speed.Radiant panels combined with fresh air systems can control temperature and humidity separately,and primarily relying on radiant heat exchange,which can effectively solve the above problems.However,the different layout of radiant panels and air supply methods can affect indoor thermal comfort and system energy consumption.Therefore,this study selected three commonly used functional rooms in civil buildings,namely hotel rooms,small conference rooms,and offices,to conduct research on the application of radiant cooling combined with fresh air systems in these three functional rooms.First,the air conditioning systems of hotel rooms,multi-person conference rooms,and offices were divided into different schemes based on the layout of the radiant panels and the air supply method.Then,Airpak was used to numerically simulate the airflow distribution of each scheme,and the evaluation indexes such as temperature field,relative humidity field,velocity field,PMV,air age,and CO2 concentration field distribution of typical sections of each functional room were obtained.The long-wave radiation model was then used to calculate the radiation heat exchange of personnel indoors and the percentage of total sensible heat.Subsequently,a comparative analysis was carried out on each scheme based on each index,and each scheme were ranked.Finally,the Analytic Hierarchy Process was used for comprehensive comparative analysis to determine the optimal scheme for each functional room based on the final weights assigned to each scheme.The research results show that the optimal scheme for hotel rooms is top-mounted radiant panel combined with displacement ventilation.The radiative heat exchange of indoor occupant in a sitting posture is 33.39 W,accounting for54.74% of the total sensible heat load of the occupant.In a standing posture,the radiative heat exchange is 40.94 W,accounting for 67.11% of the total load.In the case of conference rooms,due to the higher heat output and moisture and CO2 production from the increased number of people,the difference from hotel rooms is significant.The best scheme for conference rooms is top-mounted radiant panel combined with overhead air supply.The radiative heat exchange of indoor occupants in a sitting posture is 503.84 W,accounting for 49.98% of the total sensible heat load of the occupants.In a standing posture,the radiative heat exchange is 614.24 W,accounting for 60.94% of the total load.In offices,the radiant panel can be used as a partition in the workstation.The simulation results show that the best scheme is to use enclosed workstations with four radiative panels and overhead air supply.In case of cost limitations,two parallel installed radiative panels with overhead air supply can be used.When using enclosed workstations with four radiative panels and overhead air supply,the radiation heat exchange of personnel in the workstation is 42.6W,accounting for 69.84% of the total sensible heat load,and when using two parallel installed radiative panels with overhead air supply,the heat exchange is 37.61 W,accounting for 61.66%.The simulation results of the airflow distribution for different schemes of the three types of functional rooms in this study can provide technical reference for the design of radiant cooling combined with fresh air systems in civil buildings.