Energy balance analysis of HVAC divided flow fittings

摘要

Energy balances are performed on selected converging and diverging flow tees and laterals to calculate the net energy loss in order to quantify the total energy loss expected for a particular application. The goal is to identify those divided flow fittings that exhibit the minimum total energy loss so that the least fan power consumption will be required when such fittings are installed in an air duct system. Loss coefficient correlations previously published in literature are employed in the analysis. The total energy dissipation is expressed in terms of branch and main loss coefficients. It is shown that the total energy loss is positive within the limited accuracy of the published correlations for loss coefficient data. A physically realistic explanation is provided for previously reported negative main and branch loss coefficients. A range of branch-to-common flow rate ratios is identified for converging flow straight-body flat oval 45 degrees laterals in order to minimize energy loss.