太阳能烟囱强化自然通风的研究现状

Research Status on Solar Chimney for Natural Ventilation Enhancement

自然通风是一种节能的被动式通风冷却技术,其原理是在由温差引起的热压或风压的作用下驱动室内空间的空气自然流动,与机械通风相比,自然通风具有显著的节能优点。太阳能烟囱利用太阳辐射加热烟囱通道内的空气,提高温差,从而强化自然通风。本研究介绍了太阳能集热墙体(Trombe)式和倾斜集热板屋顶式两种典型太阳能烟囱的结构及其强化自然通风的基本原理。详细讨论了影响太阳能烟囱通风性能的主要因素,并介绍国内外学者对太阳能烟囱的主要研究方法和相关研究成果。太阳能烟囱的高度和深度(玻璃盖板与集热墙的间距)影响烟囱内空气的温升以及空气的自然对流的流动特点,从而影响了太阳能烟囱的自然通风流量。空气流量随着烟囱深度的增加而增加,但烟囱深度超过一定值后空气流量不增反减。当烟囱的深高比超过2.5后,烟囱出口端会出现逆流,从而抑制了通风量的增加。集热墙的结构以及倾斜角度对太阳能烟囱自然通风效果的影响与地理位置和气候条件等因素有关。研究太阳能烟囱自然通风的理论方法包括基于能量平衡分析的模型和基于计算流体力学的数值模拟。分析了太阳能烟囱自然通风研究中需要改进的问题。

Natural ventilation is an energy efficient passive cooling technology and it uses wind or thermal buoyancy to deliver fresh air into the buildings in order to maintain a good indoor air quality.Comparing with mechanical ventilation,natural ventilation has obvious energy-saving advantages.Solar Chimney（SC） is a vertical or inclined channel that utilizes solar radiation to cause a temperature rise and density drop for the air flowing through the chimney,therefore enhances the natural ventilation.First,two types of typical solar chimney,namely,Trombe wall-type and inclined roof-type solar chimney,and their basic principle to enhance natural ventilation are briefly introduced.Then,the parameters that influence the performance of natural ventilation of the solar chimney are discussed in detail.The major methods and result are listed based on the review of the research works on solar chimney by different authors.The height and depth（the distance between the glass cover and absorber wall） of SC influence the natural convection flow process and the temperature rise of air in the SC channel and furthermore influence the ventilation rate of the SC strongly.The ventilation air i.e.the air flow rate increases with the increase of SC depth.The air flow rate decreases when the SC depth exceeds an optimal value.A reverse flow appears near the top of the SC channel when the ratio of SC depth to height is larger than 2.5 and the increase of natural ventilation rate is limited.The effect of the SC structure and its inclined angle on ventilation is related to the geographical location and climate conditions.The modeling of SC ventilation includes the mathematical modeling that is based on the energy conservation analysis on the heat transfer process of the air on the wall surfaces and the numerical simulation of the flow process that is based on Computational Fluid Dynamics（CFD） method.Based on the literature review,the issues that need to be improved in solar chimney study are analyzed.