Cross Flow Turbine Characteristic and layout

Cross Flow Turbine - Overview Advantages: Simple design Good standardisation - runner width can be adapted to design flow so it is easy to build the turbine precisely for the specified site needs Manufacturing without the need for sophisticated manufacturing facilities. Relative low production costs compared with other turbine designs

Cross Flow Turbines In 1925 Donat Banki received a patent in Budapest for his BANKI-Turbine. This turbine applied the cross flow principle, where a free jet traverses a cylindrical runner vertical to the turbine shaft.

History of Cross Flow Turbine T-series 1980 - 1982 Local manufacturing of the T3 turbine is established in Nepal and the design is adapted in several steps to optimize production. More than 100 turbines are built, chiefly for small scale mill operation. 1976 The prototype of the T1 turbine is developed for local manufacturing in Nepal. Turbines are successfully used for mill operation and village electrification 1980 Operating experience with the T1 turbine leads to the development of the T3 series turbine. The turbine is tested in the hydraulics laboratory of HTL Brugg, Switzerland. Based on tests, the design is improved

History of Cross Flow Turbine T-series 1987 - 1993 T8 turbines, an improved version of the T7 series, become the standard for village electrification schemes in Indonesia. 1985 The demand for larger output turbines leads to the development of the T7 turbine. Fabrication is established in Nepal, and later in Indonesia. 1990 - 1995 Manufacturing of T8 series turbines is also established in Nepal and Argentina.

History of Cross Flow Turbine T-series 1995 A research program is started and in collaboration with the hydraulics laboratory of the University of Stuttgart, extensive tests are conducted. Empirical design improvements result in a new design, the T12 turbine. 1994 Indonesian entrepreneurs acquire the know-how for the implementation of complete SHP projects, using T8 turbines 1995 In Nepal, demand for large turbines is met with a redesigned version of the T8 turbine.

History of Cross Flow Turbine T-series 1996 A variety of different hydraulic configurations are tested. The ultimate goal is to use the optimal configuration for a new, completely re-engineered design. 1996 Further testing, after some critical feedback from the field, leads the way to further design modifications. The design now becomes the T13 series.

T15XFLOW: A new Cross Flow design developed by ENTEC The T14XFLOW Turbine, was empirically tested in the sophisticated laboratory of the Institute for Hydraulic Machines of Stuttgart University. The Model Turbine had an output of 15 kW, the runner diameter is 300 mm. The measuring facilities guarantee for reliable results.

Efficiency Improvement

T15XFLOW: A new Cross Flow design developed by ENTEC With only 25% of the rated flow, the efficiency is still over 50%. This allow cost reduction, because a single cell CFT will be sufficient in the majority of the applications. Double cell CFT’s have two independent guide vanes, and require two regulation devices as well, which increases cost. The achieved improvements were the basis for the re-design of the turbine. Two models, with the standard runner diameter of 300 and 500 mm were developed for output above 20kW. For output up to 25kW models withv runner diameters with 100, 150 and 225mm are available

T15XFLOW: A new Cross Flow design developed by ENTEC General Assembly of T15 Cross Flow Turbine

Application limits of T15-150 Turbines

Application limits of T15-300 Turbines Application Limits T15-300

Application limits of T15-500 Turbines

Summary: Present Application Range T15 150 100 T15-500 T15-300

Pelton Turbines T14-800 T14-650 T14-500 T14-300 Pico Piccolo Future Perspective Pelton Turbines T14-800 T14-650 T14-500 T14-300 Pico Piccolo Propeller Turbines

T15 Calculation: Definition of rated head Hr without draft tube Penstock Free water level Draft Tube Hf Hg1 Hg Hg2 ~Dt Tail race canal CF Turbine Where: Hr = Rated head Hg1 = Level difference between forebay and turbine shaft Hf = Hydraulic and friction losses in the penstock (Draft tube not installed)

T15 Calculation: Definition of rated head Hr with draft tube (not recommended) Our laboratory tests proved that the suction head can not be used with the same efficiency as the head acting in the penstock due to following reasons: A ventilation valve must maintain the water level under the turbine runner free to avoid high losses in the runner. At least one runner diameter must be subtracted from the suction head. In the remaining part of the draft tube a mixture of air and water will be created. All air flowing through the ventilation valve will even be pumped out of the draft tube. The consequence is, that the density of the water is smaller. A save estimate may be 80%. Penstock Free water level Draft Tube Hf Hg1 Hg Hg2 ~Dt Tail race canal CF Turbine (Draft tube installed) Where: Hg2 = Level difference between turbine shaft and tale race Dt = Turbine runner diameter Hf = Hydraulic and friction losses in the penstock

The concept of the “Unit Turbine” To allow using model tests from the laboratory for the dimensioning of turbines with geometrical similar shape, the measuring results are converted to a “Unit Turbine”. This fictive turbine has 1 m widht, 1m diameter and an operation head of 1m. Unit Machine Ø1m – Bo 1m Model Runner Ø300mm – Bo 160mm Real Machine Ø150mm – Bo 200mm

Hill Chart of T15 Turbine

Basic T15 Calculation (best operation point) Unit Speed : n11= 38rpm Unit Flow : p11= 0.8m3/s Are numerical Values only however in SI units (m) Runner Width : Speed : Run-way Speed : Power Output : in kW

Hnet = 62.5m Q = 600l/s Dt = 300mm Calculation Example Runner Width : Speed :

Hnet = 62.5m Q = 600l/s Dt = 300mm Calculation Example Runner Width : Speed :

example Runaway Speed : Attention: If there is a high friction loss in the penstock the runaway speed higher. Maximal nrmax = nr*sqr(Hg/Hr) Power Output :

Check Application limits of T15-300 Turbines The calculation of the turbine should be checked in the application diagram. In this case two turbines T15-300 are required to produce the power. The application is above the limits in the diagram. The design was reinforced and a stainless steel runner and guide vane was used.

Example: recalculation using 2 Turbines with bo=Bt=160mm Runner Width : Power Output (per unit) :

example Runner Width : Power Output :

Upgrade of efficiency The turbine efficiency was determined with a model turbine. In reality the efficiency for larger turbine output and for wider runner is increasing. Parameter for this difference in efficiency is the power output and the specific speed (old definition ns=nt_opt*(Pt_opt)^0.5/Hnet^1.25)

T15- calculation tool A spreadsheet was developed to calculate the suitable T15 Turbine for a certain site application. The blue fields are prepared for data input. The first step is to calculate the runner width bo and then select it according to the nearest suitable standard width.

Determine the upgraded efficiency and enter it ito the blue field

Check in the application diagram by moving the green arrows to the site data (in the example the head is quite high but still acceptable if welding and quality is good)

Fill in efficiencies of generator and gear/belt

Diagram: Efficiency versus flow

Diagram: power output versus flow The rated point of operation is marked in the diagram. There is about 15% safety margin in the power if the turbine is opened above the rated position. This is required to compensate for mistakes in the head calculation or friction losses. In any case the rated power must be reached.

Losses at scheme: concerning the energy losses from water intake to the consumers all partial losses must be multiplied to get the over all efficiency (in the example below eta tot=48%)

Terima Kasih – Thank You Jl. Cisatu I no 193 Bandung 40142 Telepon/Fax: 022 203 2128 E-mail: office@entec.co.id Website: www.entec.co.id and www.entec.ch