Coaxial VETT Laboratory Trials

In December 2013 VerdErg Renewable Energy completed hydrodynamic testing of the new VETT configuration at BHR Group in Cranfield which was successful in demonstrating a much improved efficiency from the previous testing programme.



The new Coaxial VETT is designed for fluvial uni-directional flows, with improved performance from incorporating the many lessons learned during previous testing programmes. The aim of the laboratory trials was to determine the optimum configuration of the VETT by adjusting 3 key variables: the mixing tube diameter, the relative mixing tube position and the length of mixing section, whilst varying the head and the percentage of flow through the (simulated) turbine.

The test rig at BHR Group was set up with a header tank, representing the upstream water level, which feeds the stainless steel test rig under pressure before discharging into a sink tank, representing the downstream water level. A series of pumps recirculate the water from the sink tank back into the header tank. The rig was fully instrumented with pressure measurements taken at 22 locations and flow rate measurements recorded by electromagnetic flow meters. The laboratory trials successfully demonstrated a much improved hydrodynamic efficiency from the previous trials under a range of heads between 1.3m and 2m.


Conceptual Model of Laboratory Test Rig



Fully Commissioned Test Rig at BHR Group

Three demonstration days for potential partners, investors and suppliers were held once the hydrodynamic trials were complete. A turbine-generator was installed and 18 spotlights used to visibly absorb the power generated. For all previous scientific tests, the turbine had been simulated by a valve and/or orifice plates; this was the first time a real turbine was used. For safety within the laboratory the original generator was replaced by an alternator to reduce the output voltage from 230V to 12V. The pictures below show that VETT was successful in illuminating all 18 spotlights.



Commissioned rig for demonstration days complete with spotlights




18 fully illuminated spotlights