Study On Ventilation Characteristics Of Different Window Opening Forms In Independent Room

Based on the ventilation conditions of various residential buildings and ordinary office buildings without fresh air system in China,natural ventilation with windows is still the main means to improve indoor air quality and to adjust indoor temperature and humidity.However,due to the weak controllability and strong uncertainty of natural ventilation,it is difficult to predict its ventilation volume and to evaluate its ventilation effect.In this paper,two typical natural ventilation modes,double-side wind pressure ventilation and single-side thermal pressure ventilation,are selected for the study of independent rooms.A comparative study of ventilation volume and ventilation comfort was carried out for different types and opening degrees of windows.Firstly,the basic principles and calculation methods of the two natural ventilation modes are elaborated.A modified method for unsteady characteristics of natural wind based on wind pressure ventilation model is proposed.Combining with the theory of natural ventilation adaptability and ADPI index,the comfort evaluation model of natural ventilation is established.The CFD models suitable for the two natural ventilation modes are established.The meshing mode and simulation boundary conditions are given.The model can be used in the calculation of ventilation coefficient and comfort evaluation model.Secondly,the experimental scheme of natural ventilation suitable for real rooms is designed.Sixteen groups of experimental conditions are set up for different number of windows,different degree of windows and different meteorological conditions under the two ventilation modes.The ventilation coefficients are calculated from the experimental results and compared with the CFD simulation results.Among them,the minimum correlation coefficient of each wind pressure sequence of calculated and measured values is 0.746,the maximum relative error of flow coefficient is-9.7%,the maximum relative error of indoor and outdoor temperature is 9.2% and the maximum relative error of flow coefficient is-9.5% for each thermal pressure condition.Finally,the extended simulation is carried out by selecting seven types of windows,including push-pull,flat-in-open,flat-out-open,upper-suspension-in-open,uppersuspension-out-open,lower-suspension-in-open and lower-suspension-out-open.The numerical values of wind pressure coefficient,flow coefficient and comprehensive ventilation coefficient of different window types under different outdoor wind pressure modes are obtained,and the unsteady state correction of these coefficients is carried out based on the annual wind direction observation data,and the flow coefficients of three window openings under the two modes of wind pressure and thermal pressure are obtained.The velocity field and temperature field in the window area of each window type and three window openings under the two ventilation modes are compared.The average thermal sensation and ADPI values in the neutral temperature and 1.1m height plane of the room were calculated.According to the ventilation unsatisfactory rate of 5%,the minimum area ratio of each window type to meet the ventilation requirement is calculated.