Agriculture Reference
In-Depth Information
where
The peak water demand per day (m
3
/day)
Q
p
=
Q
c
Peak crop water demand (for minimum irrigation interval period)
(m
3
/day)
E
ir
=
=
Irrigation efficiency
The procedure for estimating daily crop water demand for an irrigation scheme is
described in Chapter 10 (
Crop Water Requirement
) of Volume 1. The highest value
is the peak demand.
The pumping (i.e., discharge) rate is estimated taking into account the minimum
possible solar hour (i.e., here pumping hour) from the relation:
Q
P
=
(
Q
×
H
S
)
×
3600
or,
Q
=
Q
P
/
(
H
S
×
3600)
(13.2)
where
The peak water demand per day (m
3
/day)
Q
p
=
the discharge rate of the pump (m
3
/s)
H
s
=
Q
=
minimum possible solar (bright sunshine) hour (i.e., pumping hour) per
day for the peak period
3,600
=
conversion factor, to convert hour into second
The peak energy demand (kW),
P
E
, is calculated by taking into account the total
head requirement and pumping plant efficiency (
E
p
):
P
E
=
(
Q
×
9.81
×
H
)/
E
P
(13.3)
where
P
E
=
The peak energy demand (kW)
the discharge rate of the pump (m
3
/s)
Q
=
H
total pumping head required (m)
E
p
=
=
pumping plant efficiency
Here,
H
includes suction head, delivery head, velocity head, and head loss due to
friction in pipe and pump casing.
The number of PV array (
N
PV
) required to meet peak energy demand is
calculated as:
N
PV
=
P
E
/
(
R
S
×
A
PV
)
(13.4)
where
P
E
=
Peak energy demand (kW)
Solar irradiation per unit surface under the location in question (kW/m
2
)
A
PV
=
R
S
=
Area of each PV array (m
2
)
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