Numerical and experimental investigations of a condenser fan add-on device

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Vairtex Canada Inc. (Ottawa, ON) developed a de-swirling passive device unit to be added on top of the fans of industrial air-cooled condensers, which are normally installed at the rooftop of grocery stores as part of their refrigeration systems. Due to the simplistic design of the commonly used axial fans in these units, part of the heated flow coming from the condenser that passes through the fans will recirculate to the side and lower inlets of the unit. In addition, recirculation zones just above the fan, close to the axis of rotation, will also attract heated air back into the unit. The de-swirling passive device units redirect the flow upwards and minimize recirculation, thus improving the performance of the unit, at the same time reducing maintenance of the electrical motors that drive the fans by reducing overheating. Vairtex Canada Inc. is interested in partially optimizing its units (length size and angle of passive blades) for particular applications by applying computational tools and careful energy balance experiments of an actual size single-unit assembly. Fluid flow and temperature measurements will be performed using hotwire anemometry and thermocouples using a traverse system at the midplane of the flow downstream of the fan (with and without the Vairtex unit). An energy balance of the fan will be performed. This data will be used as boundary conditions for a numerical simulation using standard CFD (Computational Fluid Dynamics) techniques.