6.48 mm diameter nozzle delivering 0.91 l/s to the runner which is rotating at 1084 rpm and generating 225 watts into the grid at an overall efficiency of 47%.

Thursday, 23 April 2020

Changing a nozzle - in 28 seconds !



Covid 19 lockdown is making me experiment with new ways (for me) of using digital media.
Here, filmed in time lapse, is the bottom nozzle being changed for a smaller one because water supply is drying up.
The smaller nozzle also required two spacer washers to be added under the Smart Drive rotor - but filming of that didn't work out; maybe I'll try again and add it later .
Enjoy !

...next day:
it turned out that two washers generated fewer watts than one washer so today I removed one; here is the video in real time:


you'll see that: 

  • the rpm before removing the washer, when the turbine was connected to the grid, was 1152
  • the rpm after removal was 1218, but this was before the inverter had established connection to the grid
  • when the inverter established grid connection, rpm came down to 1058


The effect of this exercise is seen in the record below of output to grid: power output rose from 443 W to 468 W.
And this means that overall efficiency is better at 1058 rpm and one washer (53.6%) than at 1152 rpm and two washers (50.9%).
 A nice demo of how fine tuning can gain a few watts.



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