1. Small Scale Hydropower Optimization
Jill Nieborsky, Kelly Jobes, Phil Arpke, Jamin Juhasz, Karl Krohmer
Customer: John Law
X-Stream Team - Design Review
1/14/2019

2. X-Stream Team - Design Review
Problem Statement
Optimize an existing small-scale hydropower system to be used for residential heating
Turbine is powered by the spring run-off of Randall Creek
Original system designed and installed by a senior design team during the 2001/2002 school year
The generator is rated at 5HP (3.7 kW) and should be capable of reaching its rated power from the available potential energy created by the water.
Last spring during maximum flow, the generator only provided 1kW of power
Our goal:
Define inefficient mechanical and electrical characteristics
Improve the existing mechanical and electrical efficiency to increase power to 3.5 kW for heating customer’s home.
Jill
Optimize an existing small-scale hydropower system to be used for residential heating
Turbine is powered by the spring run-off of Randall Creek
Original system designed and installed by a senior design team during the 2001/2002 school year
The generator is rated at 5HP (3.7 kW) and should be capable of reaching its rated power from the available potential energy created by the water.
Last spring during maximum flow, the generator only provided 1kW of power
Our goal:
Define inefficient mechanical and electrical characteristics
Improve the existing mechanical and electrical efficiency to increase power to 3.5 kW for heating customer’s home.
X-Stream Team - Design Review
1/14/2019

3. X-Stream Team - Design Review
Constraints
Existing components
Already been chosen by the customer and previous design team
Limited budget
All expenses are out of our customer’s pocket
Possibility of a sponsorship through Clearwater Power
Field-testing
Randall Creek is a seasonal creek, therefore, we cannot run any field testing until January, at the earliest
In lab conditions are dissimilar to field conditions
Currently have not been able to measure flow rate
Field flow rate is unachievable in lab
Engineering designs for lab will be different than for field
Jill
Existing components
Already been chosen by the customer and previous design team
Limited budget
All expenses are out of our customer’s pocket
Possibility of a sponsorship through Clearwater Power
Field-testing
Randall Creek is a seasonal creek, therefore, we cannot run any field testing until January, at the earliest
In lab conditions are dissimilar to field conditions
Currently have not been able to measure flow rate
Field flow rate is unachievable in lab
Engineering designs for lab will be different than for field
Capacitance and Nozzle
X-Stream Team - Design Review
1/14/2019

4. X-Stream Team - Design Review
Experimental Setup
Approximately 1 cfs flow provided by a 50 hp pump
4-inch inlet PVC pipe
Electrical power calculated from measured voltage and current across load on a per-phase basis
Jamin
X-Stream Team - Design Review
1/14/2019

5. X-Stream Team - Design Review
Field Setup
Jamin
12-inch PVC penstock pipe transitioned down to a 3x6-inch nozzle
24 feet of head
X-Stream Team - Design Review
1/14/2019

6. X-Stream Team - Design Review
Research Areas
Mechanical
Cross flow turbines
Housing design
Nozzle design
Fluid mechanics calculations
Belt and pulley types
Electrical
Providing VARs with excitation capacitance
Maximum power transfer using load impedance matching
Karl
Capacitance: different levels of shunt capacitance can affect the output power of the generator
X-Stream Team - Design Review
1/14/2019

7. Cross Flow Turbine Selection
Decision by previous design team
Crosses through turbine twice
Up to 80% efficient
Best turbine for small scale applications
Phil
X-Stream Team - Design Review
1/14/2019

8. X-Stream Team - Design Review
Existing Housing
Problems with housing
Turbine runner doesn’t operate as a cross-flow turbine should
Water ‘cuts’ through itself
Nozzle isn’t using all available runner area due to housing constraints
Phil
X-Stream Team - Design Review
1/14/2019

9. X-Stream Team - Design Review
New Housing
Improvements on housing
Open up to keep water from ‘cutting’ through itself
More available runner area for nozzle
Phil
X-Stream Team - Design Review
1/14/2019

10. Nozzle design considerations
Energy equation derivation shows that velocity is constant at nozzle exit
Maximum turbine RPM about 700
Want to increase torque delivered to turbine
Flow rate and pressure are dependent on the outlet area of nozzle
Power calculated from pressure and velocity at nozzle exit
No Nozzle
Mundy Nozzle
% Increase
Speed
Torque
10.75
16.125
27.92%
50.00%
240
307
Jamin
Current layout
12” dia. to 6” dia.
Transition from 6” round to 3”X6” rectangle
Enclosed housing
X-Stream Team - Design Review
1/14/2019

11. X-Stream Team - Design Review
New nozzle design
Jamin
Take advantage of the full width of the blades
Same hydraulic diameter of the 6” inlet pipe
Goes from 6” round to 5.25 X 7” rectangle
May be one or two pieces
Other considerations are including vanes, and creating an adjustable nozzle.
Lab test data not sufficient to do accurate calculations at this time
X-Stream Team - Design Review
1/14/2019

12. Pulley and Gear Lab Results
The big pulley has an OD of inches
The small pulley has an OD of 2.5 inches
Final speed ratio should be 5.5:1
Lab results showed 5.7:1 average ratio
4.5% power loss
Run
Speed (rpm)
Speed ratio
Turbine
Generator 1
159.65
915
5.73 2
195.36
1113
5.70 3
237.01
1340.3
5.66 4
239.71
1372.7 5
197.13
1122.3
5.69 6
198.22
1132.6
5.71
Average:
Phil
X-Stream Team - Design Review
1/14/2019

13. X-Stream Team - Design Review
Belt Drive Systems
4.5% power loss from existing v-belt system
Slippage
Thermal expansion
Cog belt system 100% efficient
Phil
X-Stream Team - Design Review
1/14/2019

14. Excitation Capacitance
Per-phase equivalent circuit of a Self-Excited Induction Generator with R-L loading
The shunt capacitance (C) provides the VARs for the induction generator, balancing out the inductive characteristics of the machine.
The magnetizing inductance (Lm) must be supplied reactive power in order to create the rotating magnetic field inside the machine.
This rotating magnetic field is necessary in order to generate output voltage.
Karl
X-Stream Team - Design Review
1/14/2019

15. X-Stream Team - Design Review
Impedance Matching
For max power transfer from a source to a load, the source impedance must equal the complex conjugate of the load impedance
Assume capacitive reactance will cancel out the inductive reactance, leaving a purely resistive load
Max power transfer occurs when the impedance of the source equals the load in a purely resistive situation
Important to do so that we get max power and max heat for our fixed resistance
Rs + jXs = RL - jX
Jill
For max power transfer from a source to a load, the source impedance must equal the complex conjugate of the load impedance
Assume capacitive reactance will cancel out the inductive reactance, leaving a purely resistive load
Max power transfer occurs when the impedance of the source equals the load in a purely resistive situation
Important to do so that we get max power and max heat for our fixed resistance
X-Stream Team - Design Review
1/14/2019

16. Plan for System Improvements
Bigger nozzle design
Improved housing design
More efficient belt/pulley system
Match load impedance for maximum power transfer
Find optimum capacitance to maximize power output
Kelly
X-Stream Team - Design Review
1/14/2019

17. X-Stream Team - Design Review
Budget
Jill
Budget proposed by customer
In-house construction that will lessen costs
Nozzle
Housing mods
Presentation materials
X-Stream Team - Design Review
1/14/2019

18. Project Deliverables Timeline
Dec. 1…………Completion of design
Jan. 1…………Completion of lab testing
Jan. 20………..Field testing
Feb. 1…………Analyze field data
Feb. 10……….Troubleshoot system
Expo…………..Present final project design
Kelly
X-Stream Team - Design Review
1/14/2019

19. X-Stream Team - Design Review
Future Challenges
Optimizing our lab results when we cannot simulate field conditions in the lab.
Creating a shunt capacitance curve to link optimum lab capacitance with optimum field capacitance.
Understanding why past design team had better lab results under same conditions.
Learn how to use the Pressure Transducer.
Kelly
X-Stream Team - Design Review
1/14/2019

20. X-Stream Team - Design Review
Questions?
Team
X-Stream Team - Design Review
1/14/2019