Experimental Investigation of Performance of a Pump-Turbine Fitted With Nylon-PA12 Impeller

Abstract

The standard of life in high terrain villages that do not have access to electricity can definitely be
made better by making electricity available. The supply through grid to these high terrain areas is
not feasible and economical and requires alternative means for electrification. Amongst the various
renewable energy options Pico scale (few hundred watts-5kW) standalone hydro power generation
proves to be advantageous in these areas if natural streams of water are available. Conventional
custom designed hydro turbines are energy efficient but are expensive. Francis turbine is similar in
many ways to a centrifugal pump except that pumps do not have flow control devices such as guide
vanes. Pumps being mass produced are cheaper, much readily available and are much simpler in
construction. Owing to these advantages pumps utility as hydro turbine has been explored by many
researchers. Cast iron, brass, bronze, stainless steel are some of the most commonly used materials
for pump impellers. Much of the research on pump-turbine has been with pumps fitted with impeller
made from these materials. The pumps are reported by many researchers to have slightly lower
efficiency in turbine mode operation at best efficiency point and their part load performance is also
reported to be poor in turbine mode. Researchers have attempted performance improvement of
pump-turbine through impeller edge rounding and vane tip rounding etc. This paper presents the
experimental investigation of performance of a pump in turbine mode; the pump is fitted with NylonPA12 impeller made by selective laser sintering- 3D printing technology.