Simulation-based method for HVAC air-side system balancing (1): Correction for close-coupled

 Due to the tedious measurements and unsatisfactory quality of the conventional testing, adjusting and balancing (TAB) process for HVAC air-side systems, presents performing the balancing procedure on the system models prior to the on-site TAB, so that the on-site work could be guided and improved. First, mainly focuses on the resistance models of the duct fittings. Most of the existing models do not account for the close-coupled effect when the fittings are closely connected. Adopts CFD simulation method to calculate the coefficient of local resistance of junctions, dampers and bends under five different connection arrangements. Proposes a new correction method for the close-coupled effect. Regresses the correction models based on the CFD results. The results show that the models could compensate the significant influences of the close-coupled effect on the fittings’ coefficient of local resistance.