本次调查的目的是确定是否可以开发一个简单的设计程序来预测接收点的浓度降低，如果排气管高度或其出口速度发生变化，则会发生这种降低。重点是发展一个简单的理论，而不是尝试适用于各种情况的更一般、更准确的公式。这种对简单性的强调是合理的，因为建筑物周围稀释过程的可变性在预测浓度时引入了两个或两个以上的不确定性水平，任何改善这种不确定性的烟囱高度效应理论都是一种自我实践- 设计师的错觉。实验结果和简单理论将证明，叠加高度和垂直出口速度可以结合起来确定有效叠加高度。这是一个重要的概念，因为它允许设计师在增加堆栈的物理高度或增加堆栈的垂直速度之间进行权衡。由于排出给定数量的排气所需的风扇功率与排气速度的平方成正比，因此必须回答的关键问题是，对于不需要过多风扇功率的合理排气速度，屋顶接收器浓度是否会显著降低。 如果需要较大的出口速度值，则所需的风扇功率可能会使简单地提高烟囱高度更具吸引力。本文报告的研究结果是ASHRAE研究项目136的一部分，该项目考虑了建筑物附近排放气体的稀释。威尔逊（Wilson，1,2,3）引用《美国科学院学报》（ASHRAE Transactions），第83卷，第一部分，伊利诺伊州芝加哥，对本研究的其他方面进行了讨论

The purpose of the present investigation was to determine if a simple design procedure could be developed to predict the reduction in concentration at a receptor point which would occur if either the vent stack height or its exit velocity were changed. The emphasis was on the development of a simple theory rather than attempting more general and accurate formulations which would apply to a wide variety of situations. This emphasis on simplicity is justified because the variability of the dilution process around a building introduces levels of uncertainty of two or more in predicting concentrations and any theory of stack height effects which improves on this uncertainty is an exercise in self-delusion on the part of the designer.The results of the experiments and the simple theory will demonstrate that both the stack height and the vertical exit velocity can be combined to determine an effective stack height. This is an important concept because it allows a designer to determine a trade-off between increasing the physical height of the stack or increasing the vertical velocity from the stack.Because the fan power necessary to exhaust a given quantity of vent gas is proportional to the square of the vent gas velocity the key question which must be answered is whether there is any significant reduction in roof receptor concentrations for reasonable vent velocities which do not require excessive fan power. If large values of exit velocity are required the necessary fan power may make it much more attractive to simply raise the height of the stack.The results of the study reported here are part of ASHRAE Research Project 136 which considered the dilution of vented gases near buildings. Other aspects of this study are discussed by Wilson (1,2,3)