A Field Study And Model Analysis On Ventilation Rate In Single-sided Natural Ventilation Building

As a passive energy-saving technology,natural ventilation which can improve indoor air quality and thermal comfort environment at the same time attracts people's attention under national energy-saving policy.Wind-driven single-sided ventilation,comparing with cross ventilation,has better security and protection of privacy,thus has very important significance in study.The thesis aims to measure the ventilation rate of single-sided natural ventilation building and analyze ventilation rate models.Firstly,the academic background and practical meaning of unsteady wind-driven single-sided ventilation was presented.Then the state of research on mechanism,full scale measurement,measuring method and its application was reviewed.Secondly,a full scale single-sided mean ventilation experiment using tracer gas decay method was carried out in a typical office building in Wuhan.The geometry of experimental room,instruments and working conditions were described,especially ultrasonic meteorological station,anemometer and tracer gas analyzer.And the calculation of mean velocity and multi-point method were presented.Then by analyzing the variation of measured mean ventilation rate brought by work conditions,a dimensionless mean ventilation rate model was put forward.Comparing the dimensionless mean ventilation rate model and existing mean ventilation rate models,it was found that all these models agree well with experimental data.Thirdly,a full scale single-sided instantaneous ventilation experiment using dry ice method,one kind of constant emission technique,was carried out in the identical office.The experimental procedure and measurement method of dry ice method were presented,so as the calculation method of constant emission technique.By analyzing the calculated instantaneous ventilation rate and instantaneous velocity,an instantaneous ventilation rate model was put forward.Comparing the instantaneous ventilation rate model and existing instantaneous ventilation rate model,it was found that the instantaneous ventilation rate model this paper put forward applies to large fluctuating ventilation condition while existing instantaneous ventilation rate model applies to small one.Finally,the mechanism of shear layer ventilation and calculating model of shear layer ventilation rate were presented.By comparing measured shear ventilation rate and calculated shear ventilation rate,it was found that dimensionless shear layer ventilation is independent of velocity and opening area.And it also found that Chia Ren Chu's model applied wisely and accurate.The conclusion as a part of unsteady single-sided natural ventilation mechanism can provide instructional support for accurately estimating natural ventilation rate and using natural ventilation technology in some degree.