Bicycle Powered Centrifugal Irrigation Pump, Constant Power Varied Head Experiment

I wanted to measure the efficiency of the bicycle irrigation pump for a
range of vertical heads, which represents farms with hills or the pressure head
from using sprinklers. I also wanted to compare the bicycle pump’s efficiency
to an existing human powered pump. In particular, I compared flow measurements
to the published results of the Saajhi stepping pump, which is a portable
treadle pump made by Xylem, Inc.

Procedure: Constant Power, Varied Head

The power meter’s readout software6F[1]
did not display a live power reading but did display a live cadence reading. Cadence
is a proxy for power if the applied torque is constant. To control the input
power in this experiment, the pedaler watched the readout of cadence and tried
to keep it at a level that would correspond to 100 watts7F[2].
We then took multiple trials (3 to 6 trials) at vertical heads ranging from 1
to 5 meters in increments of 1 meter. We changed the vertical head by moving
the outlet hose up a staircase. The vertical head was measured on a staircase
using a laser distance meter.

In each trial, once the pedaler reached a stable cadence and
torque, they would start a timer and simultaneously call out to the person at
the outlet of the hose (the “outlet person”) to switch the water flow from
filling an auxiliary bucket to filling the measurement bucket. The outlet
person would then call out when the measurement bucket was filled to 20 liters,
and the pedaler would stop the timer. Thus, I measured input power, height (the
independent variable), time, and volume (volume over time describes the flow
rate, which was the dependent variable).

[1]
The software distributed with the DZero power meter, Qalvin BLE, did not
record data. The compatible app that did record data Wahoo Fitness did
not display live power readings.

[2]
The usual case will be that a farmer pedals at a constant sustainable rate
which we targeted to be 100 watts (0.13 horsepower). According to Water
Lifting Devices, an average adult can maintain an output of over 100 watts
for more than an hour.