置换通风的原理及应用

在过去的十多年中，置换通风系统在北欧国家得到了大量应用并显示出极大的优势。本文介绍了置换通风的原理及其在工业民用建筑中的应用实例，用通风效率、换气效率和热舒适性指标比较了置换通风与混合式通风的优缺点，最后指出置换通风系统在控制污染物、改善空气品质方面极强的生命力。     

排除人员活动区内人体释放污染物的有效通风方式--置换通风

分析了置换通风和混合通风的原理。基于气流分布特性和双层模型理论，比较了这两种通风方式的排污能力。对办公室、会议室及体育馆置换通风系统的通风效率进行了实测。结合人体释放污染物的气流运动特性，指出以排除人员活动区内人体释放污染物为目的时，置换通风较混合通风更为有效。     

置换通风的通风效果及其节能评价

本文简要介绍了置换通风的原理和特性，从评价气流分布性能的各项指标及能耗出发，分析了置换通风与传统通风相比表现出的优势，指出置换通风应该在我国工程中得到更广泛的应用和推广。     

风口侧上置置换通风的热舒适性实验研究

以小型办公室为实验模型,采用了5组对比工况进行了实验,并将实验值与模拟值进行了比较,结果二者吻合较好。分析了侧墙上置风口置换通风的热舒适性。结果表明风口侧上置置换通风在各设计工况下,其负荷承担能力要大于传统置换通风,并且不论是吹风感、吹风温度还是室内头脚垂直温差都满足人体热舒适。这也证实风口上置置换通风与传统置换通风一样,可以在室内形成良好的热力分层现象,并且其能很好地满足人体的热舒适性需求,具有置换通风系统的特性。     

置换通风在工业厂房通风中的应用

置换通风是近些年来发展起来的一种新型通风方式。本文介绍了置换通风的原理与特 性,新的通风评价方法。探讨置换通风在厂房通风中的应用,提出了置换通风中的一些问题 及改进的初步方法。指出了置换通风是一种值得推广的通风方法。     

不同柱体布局模式下圆柱贴附通风气流组织特性研究

针对大空间建筑中存在的多种圆柱布局模式,研究了单、双及四柱贴附通风气流组织特性。选取14种柱体布局模型,采用流场可视化实验和数值模拟方法研究了圆柱贴附通风的流场形态和气流组织特性,并选取速度场、温度场、头脚温差、吹风感指数和通风效率分析了4种单柱布局模式的通风性能。结果表明:单、双及四柱贴附通风均能在工作区形成类似于置换通风的空气湖气流组织分布;双柱和四柱贴附通风可以简化为单柱通风模式来研究。     

通风效率的规律性问题

按照不同的通风方法,讨论了三个有关通风效率规律性的问题：用通风效率检验混合通风的实际性能;置换通风通风效率的分析与应用;我国暖通规范自然通风热分布系数更新的必要与可能性。     

风口上置置换通风的实验研究

对风口上置置换通风系统进行实验研究,得出此种通风方式下送风口的速度分布,室内的温度分布,O.1m处的风速等实验数据.通过分析实验数据得出,风口上置置换通风在满足室内热舒适性的前提下,能够提高房间的负荷承担能力,与混合通风相比能够得出较高的通风效率;另外,阶梯形的风口较普通的送风口能较少的卷吸上区品质差的空气,能更好地满足上置置换通风的风口特性要求.     

侧墙上置风口置换通风系统性能的实验研究

对侧墙上置风口置换通风在不同负荷率下进行夏季工况,过渡季节工况,冬季内区工况的系统性能进行实验研究,得出此种通风方式下送风口的速度分布,室内的温度分布,0.1m处的风速等实验数据。通过分析实验数据得出,侧墙上置风口置换通风在满足室内热舒适性的前提下,能够提高房间的负荷承担能力,与混合通风相比能够得出较高的通风效率;另外,阶梯形的风口较普通的送风口能较少地卷吸上区品质差的空气,能更好地满足侧墙上置置换通风的风口特性要求。     

从置换通风的设计原理及运行工况析其节能特性

通过对置换通风设计原理及运行状况特性的分析，来比较置换通风和混合通风的能耗，并认为置换通风整体上是节能的。     

通风效率性能参数在通风设计中应用的探讨

采用CFD的方法对不同通风方式的典型的办公室内污染物的去除进行了模拟,介绍并比较了换气效率和通风效率作为有效的室内空气品质参数在通风设计和实地测量中的应用：总共进行了3个不同的数值模拟计算,总结实验结果得出：在不知道室内污染源时,采用换气效率比较评价室内通风设计方案;而对于已知室内污染源及释放率的情况,采用通风效率作为评价标准将更准确,以便能详细地给出污染物排除情况。基于本文的研究,空调系统设计者可以根据特定的情况选择适当的参数来指导空调通风系统的设计。     

Vertical profiles of temperature and contaminant concentration in rooms ventilated by displacement with heat loss through room envelopes

The purpose of this study is to examine the effect of heat loss through walls upon the gradients of temperature and contaminant concentration in room with displacement ventilation. It is known that conduction heat loss is governed by outside temperature, heat load inside the room, supply air temperature and overall heat transfer coefficient of walls. Experiments were conducted to measure the temperature gradient and the ventilation efficiency in the room ventilated by displacement ventilation with various combinations of heat load and temperature difference between supply air and outside air. In order to simulate the change of seasons, the supply air temperature was changed instead of the outside air temperature. The effect of supply air temperature and heat generation inside the room on the temperature gradient and the concentration of tracer gas were investigated through the experiments. As a result, it turned out that the higher the heat generation rate and the lower the supply temperature, the stronger the temperature stratification and the lower the concentration in the lower zone. Additionally, ventilation heat loss turned out to be a good index for assessing the concentration in the lower zone. Temperature differences of around 3 degrees C between supply air temperature and exhaust temperature are at least needed for displacement ventilation under the conditions of the experiment presented in this paper.     

不同送风方式对室内负离子分布影响的数值模拟

采用计算流体力学方法,对混合通风、地板送风及置换通风三种工况下室内负离子的动态传播过程进行了数值模拟.通过对模拟结果进行讨论,分析了室内负离子的分布特征,结果表明,置换通风情况下负离子净化器比其余两种工况能更有效地控制房间较低位置(走动区或办公桌)产生的污染物,同时,当负离子净化器间歇运行时,置换通风工况需要最短的开机...     

Experimental investigation of heat transfer during night-time ventilation

Night-time ventilation is seen as a promising approach for energy efficient cooling of buildings. However, uncertainties in the prediction of thermal comfort restrain architects and engineers from applying this technique. One parameter essentially affecting the performance of night-time ventilation is the heat transfer at the internal room surfaces. Increased convection is expected due to high air flow rates and the possibility of a cold air jet flowing along the ceiling, but the magnitude of these effects is hard to predict. In order to improve the predictability, heat transfer during night-time ventilation in case of mixing and displacement ventilation has been investigated in a full scale test room. The results show that for low air flow rates displacement ventilation is more efficient than mixing ventilation. For higher air flow rates the air jet flowing along the ceiling has a significant effect, and mixing ventilation becomes more efficient. A design chart to estimate the performance of night-time cooling during an early stage of building design is proposed.     

通风的有效性与室内空气品质

指出了通风有效性对改善室内空气品质的重要性,比较了不同送风方式的换气与通风效率,分析了通风效率与室内污染度的关系,最后提出了关于如何提高通风效率的建议。     

Comparison of gaseous contaminant diffusion under stratum ventilation and under displacement ventilation

The gaseous contaminant diffusion under stratum ventilation is investigated by numerical method which is validated by experiments carried out. The concentration of gaseous contaminants along the supply air jet is found to be lower than the other parts of the room. Compared with displacement ventilation, the formaldehyde concentration in breathing zone is lower when a contaminant source locates close to the occupant. The concentration is at the same level when the contaminant source locates up-steam to the occupant. The concentration in the occupied zone (<1.9 m from the floor) is also lower when the contaminant source locates on the floor. At supply air temperature optimized for displacement ventilation, the toluene concentration in breathing zone for stratum ventilation is higher than that for displacement ventilation when the area source locates on the four surrounding walls of the room.     

上海体育馆置换通风系统设计研究

介绍了上海体育馆置换通风设计,采用相同的原始数据与设计参数,按照现行的暖通规范与混合通风设计作了比较。计算显示出置换通风在室内空气品质和节能上的优势及其在应用场所上的局限性。