Internal flow path improvement for pressure loss reduction in heat recovery ventilation system using CFD

Abstract Energy-recovery ventilators (ERV) exhaust polluted indoor air while supplying outdoor fresh air and recovering energy via heat and mass exchange. Their adoption is rapidly increasing because they simultaneously improve indoor air quality and reduce building energy consumption. This study quantifies the pressure-loss contribution of a sliding bypass damper’s gear-support bracket located in the ERV damper space of a 350 m³/h unit comprising a desiccant rotor and heat-pump dehumidification. We employ steady, incompressible RANS CFD (Reynolds averaged Navier-Stokes computational fluid dynamics) using the realizable \: k-\: \: turbulence model and an experiment-based porous-media method. Four internal flow paths are analyzed: OA (Outdoor air) to EA (Exhaust air), OA to SA (Supply air), RA (Return air) to EA, and RA to SA. To reduce computational cost, the section from the OA/RA inlets to the heat-exchanger face, rotor/fan rotation, and thermal effects are excluded from the domain. The fin-tube heat exchanger and desiccant rotor are modeled as porous media; their viscous and inertial resistances are inferred from dedicated fin-tube pressure-drop tests and manufacturer data and were used to validate the CFD model. Removing the damper gear-support yields the largest benefit in the OA to SA path: at 450 m³/h the total pressure drop decreases by 11. 9%. In RA to EA, however, improving inlet-face flow uniformity is identified as a more effective strategy than bracket removal. For OA to EA and RA to SA, the effect of bracket removal is marginal. Across all paths, net pressure-drop reductions of 1. 78%, 4. 61%, and 4. 77% are obtained at 250, 350, and 450 m³/h, respectively. Based on these findings, we suggest replacing the sliding bypass damper (or redesigning its support) and pursuing additional loss-reduction measures such as inlet-face flow conditioning and inlet/outlet alignment. The results demonstrate that CFD, coupled with experiment-informed porous-media modeling, is an effective tool for guiding low-cost internal-flow improvements that reduce ERV pressure losses.