Discharge rate - performance

Poor performance can result from fan inlet eccentric or spinning dow, and discharge ductwork that does not permit development of hiU fan pressure. Sometimes inlet restrictions starve a fan and limit performance. To obtain rated performance, the air must enter the fan uniformly over the inlet area without rotation or unusual turbulence. This allows all portions of the fan wheel to do equal work. If more air is distributed to one side of the wheel, such as with an elbow on the inlet, the work performed by the lightiy loaded portions of the wheel is reduced and capacity is decreased by 5—10%. The use of an inlet box duct on a fan can reduce capacity by as much as 25% unless there are turning vanes in the duct. Use of the vanes reduces the capacity loss to around 5%. 

Fig. 8. Sedimentation equipment performance where the particles have a A5 value of 1.0 g/cm and a viscosity, p., value of 1 mPa-s(=cP). The value of is twice the settling velocity at G = 1, and Q = overflow discharge rate in measurements given.

The so-called zinc chloride cells are basically Leclanche cells in which the ammonium chloride has been completely, or almost completely, replaced by ZnCl2. (Up to 1 % of NH4CI is reported to improve high rate performance.) The resulting cells have a better service capacity at high current drain, at low temperatures and on continuous discharge. 

The main advantages of Ni/Cd over lead-acid batteries is the higher discharge rate possible and the longer cycle life. At an 8-hour discharge rate (C/8), the two batteries may be nearly equal in energy density, but at a 30 minute rate (2C) the Ni/Cd battery still performs well whereas the lead-acid battery can barely work, losing 80% of its capacity or more. 

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