Question 2
A modern pumped storage scheme, the Gwynedd plant at Llanberis, North Wales, consists of six
Francis turbines with a total power output P= 1728 MW, a volume flow rate Q= 60 m³/s for each
turbine, a head H= 600 m at full capacity, operating at a rotational speed of 500 rpm. When
pumping the water back to the upper reservoir, the demand on the electricity supply is 33%
greater than it was in the turbine mode.
Determine,
2.1. the efficiency of the turbines and their specific speed, comparing the value you obtain
with the range of values in Figure Q2, comment on the suitability of these turbines for the
task;
(8)
2.2. the diameter of the turbines assuming a peripheral velocity factor for the turbines of 0.75;
(3)
2.3. the efficiency of the system in the pumping mode.
1
FMA3602 ASSIGNMENT 1
4/2022
(4)
[15]
