热压作用下新风系统水力工况分析方法研究
Analysis method for hydraulic condition of outdoor air system under thermal pressure
摘要：
热压作用导致通过竖直立管送风的空调新风系统水力失调且并联管路阻力不平衡,无法计算管网阻抗及进行水力工况分析,针对该问题提出了适用于热压作用下的新风系统水力工况分析方法。该方法将整体管网看作并联的各末端通风支管虚拟闭合环路,求解压阻平衡方程组,拟合了各闭合环路与管网的特性曲线方程,确定了虚拟闭合环路阻抗,实现了热压作用下管网流体流动及流量分配规律的描述。计算中考虑了管网流量与摩擦阻力系数、局部阻力系数的耦合关系。以某办公楼新风系统为例,利用环路阻抗方法对热压作用下管网的水力工况进行了分析,其计算结果与方程组迭代计算结果相吻合,表明了所提方法的准确性。
Abstract：
Thermal pressure results in the hydraulic imbalance of outdoor air systems supplying air through vertical risers and the unbalanced resistance of parallel pipes, so it is impossible to calculate the pipe network impedance and analyse hydraulic condition. For this problem, a hydraulic condition analysis method for outdoor air systems under thermal pressure is proposed. In this method, the whole pipe network is regarded as the virtual closed loop for each end ventilation branch pipe in parallel, the pressure-resistance balance equation system are solved, the characteristic curve equations for each closed loop and pipe network are fitted, and the impedance of virtual closed loop is determined. The description of fluid flow and flow distribution law of pipe network under thermal pressure is realized. The coupling relationship between the pipe network flow, friction resistance coefficient and local resistance coefficient is considered in the calculation. Taking the outdoor air system of an office building as an example, the loop impedance method is used to analyse the hydraulic condition of the pipe network under thermal pressure.The calculated results are consistent with the iterative calculation results of the equation system, which proves the accuracy of the proposed method.
Keywords:hydraulic condition; outdoor air system; thermal pressure; loop impedance; virtual closure; resistance characteristic; flow rate