Feature
Rickard Air Diffusion
Remote monitoring of various building diffusers is possible .
was natural progression and evolution of the fan where today fans use half the energy consumption from the belt-driven era . From those days , it was simple to reduce consumption by those margins , while today a mere couple of percent proves great advances in technology .
“ Considered pioneers of the EC technology , ebm-papst in fact started producing these fans in the 70s for small or compact fan ranges . EC fans essentially make use of direct current ( DC ) motors . Although these products are supplied with AC connectivity , internally they are converted into DC . The reason for this is that DC motors run at a much higher levels of efficiency . The physical construction of the motor is also different . In a conventional motor your winding is on the outside , and the rotor sits on the inside . You add AC current through the windings that creating a secondary induced magnetic field in your rotor , thus creating movement . Conversely with EC fans , the winding sits on the inside , and the exterior rotates ,” adds Schoombie .
EC technology has seen the largest development because with the configurations using VSDs , control obviously meant being able to limit capacity and when you don ’ t need the fan , to be able to slow it down or turn it off obviously saves a lot of energy . Incorporating this methodology into an inline EC unit achieved the same results with fewer components , additional cabling , noise management and harmonic disturbances .
Fan sizes and blade or impeller designs have also seen development over years as more compact units are required by the markets . Blade orientation and shape have also seen changes through scoop or push ( depending on forward or backward design ) that allow fans to operate under different parameters .
“ Forward curve impeller blades are used in higher air volume application , but not for high pressures . Backward curve blade fans on the other hand can handle much higher pressures . The fan type was developed to be installed into , for example , an air handling unit that has multiple filters . In the past there was a primary and maybe a secondary filter in an AHU , where today tertiary filters , HEPA and ULPA filters need to be considered that greatly increase the pressure a fan must handle ,” says Schoombie .
Further , fan blade shapes have been improved , again based on aerodynamic principles with the intention of
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RACA Journal I June 2021 www . hvacronline . co . za