Nowadays, I have investigating the frost growth at unit cooler evaporator, considering real fan effects. I have encountered that as the pressure drop increases almost linearly up to a top point of fan pressure drop (specified at fan-curve table), after that point, the curve of pressure drop fluctuates (this condition is entitled as fan stall condition) and drops sharply after a while. I am wondering that whether the operating of fan at this stall area has negative impacts on fan or not... Thank you for helping and recommandation in advance.
If your fan is operating under stall, since the airflowrate decreases, the heat transfer to the evaporator will also decrease. Try to stay close to the the design point of yor fan in H-Q (deltaP-Q) curve to imrove heat exchanger performance.
Regards,
Salih
Operating an axial fan in the stall region will have a negative impact on the fan. Fluctuating pressure means dynamic loads on fan blades and bearings, which eventually will lead to fan failure. In the end, it depends on the fan's mechanical capability if it will fail.
Thank you very much Dear Sirs, according my experience at the practical applications, most of the unit cooler running under frost condition has been operated over the design pressure drop due to lack of exact defrost control system. Accordingly, in case of such usage, axial fans may damage in further time.
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