基于能级理论的水环热泵系统节能性分析

为研究水环热泵系统节能性，提出能级理念。基于此研究理念，采用系统内部循环水作为研究对象，以负荷率作为研究切入点，提出“能级差分析方法”作为系统运行工况节能性分析方法并以能级差数ψ作为节能性新的评价指标。选取天津地区单体办公建筑作为试验对象，对传统空调系统与水环热泵系统进行夏季20％，40％，60％，80％和100％5档能耗测试，基于对非标工况研究意义的考虑，提出“部分负荷率无因次分析方法”对试验数据进行分析处理。结果表明：能级差数是负荷率的单值函数；系统仅在满负荷工况段相比传统空调系统不具有节能性。随负荷率的变化，水环热泵系统能耗呈现非线性变化规律，能耗曲线畸变工况点出现在80％-100％负荷段。

地铁区间隧道的烟气逆流长度与临界风速

采用因次分析方法推导了地铁区间隧道火灾烟气逆流长度的无因次表达式;以重庆地铁6号线为例,开展了区间隧道形状的调查,选择了9种不同断面形式的区间隧道,采用FDS5.5模拟计算了隧道火灾烟气运动状况,进而提出了烟气逆流长度和临界风速的预测模型,并进一步建立了几何比例尺为1∶10的地铁区间隧道模型实验台来开展小尺寸试验研究.结果表明:文中提出的烟气逆流长度和临界风速的预测模型的模拟结果与小尺寸试验结果吻合较好;相比于文中提出的临界风速预测模型的预测结果,现有的预测模型预测的临界风速偏小.

Discriminated Dimensional Analysis Versus Classical Dimensional Analysis and Applications to Heat Transfer and Fluid Dynamics

In contrast to classical dimensional analysis, discriminated dimensional analysis assumes that spatial coordinates are dimensionally independent of each other and allows other types of geometrical quantity to be used in the dimensional basis, such as surfaces and angles. As a consequence, discriminated dimensional analysis leads to a lower number of dimensional groups, which makes the solution more precise. Besides, these discriminated groups have a clear physical meaning in terms of force and energy balances. The paper introduces this technique and provides dimensional equations for the main quantities and physical parameters of the heat transfer and fluid flow fields. Two applications are presented to demonstrate the efficiency of this method.