Small Scale Hydropower Optimization Jill Nieborsky Kelly Jobes
Small Scale Hydropower Optimization Jill Nieborsky, Kelly Jobes, Phil Arpke, Jamin Juhasz, Karl Krohmer Customer: John Law Page 1 X-Stream Team - Design Review 11/6/2020
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 5 HP (3. 7 k. W) 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 1 k. W of power • Our goal: – Define inefficient mechanical and electrical characteristics – Improve the existing mechanical and electrical efficiency to increase power to 3. 5 k. W for heating customer’s home. 2 X-Stream Team - Design Review 11/6/2020
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 • • • 3 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 X-Stream Team - Design Review 11/6/2020
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 4 X-Stream Team - Design Review 11/6/2020
Field Setup • 12 -inch PVC penstock pipe transitioned down to a 3 x 6 -inch nozzle • 24 feet of head 5 X-Stream Team - Design Review 11/6/2020
Research Areas • Mechanical – Cross flow turbines – Housing design – Nozzle design – Fluid mechanics calculations – Belt and pulley types 6 • Electrical – Providing VARs with excitation capacitance – Maximum power transfer using load impedance matching X-Stream Team - Design Review 11/6/2020
Cross Flow Turbine Selection • Decision by previous design team • Crosses through turbine twice • Up to 80% efficient • Best turbine for small scale applications 7 X-Stream Team - Design Review 11/6/2020
• Problems with housing – Turbine runner doesn’t operate as Existing Housing a cross-flow turbine should • Water ‘cuts’ through itself – Nozzle isn’t using all available runner area due to housing constraints 8 X-Stream Team - Design Review 11/6/2020
• Improvements on housing New Housing – Open up to keep water from ‘cutting’ through itself – More available runner area for nozzle 9 X-Stream Team - Design Review 11/6/2020
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 Speed 10 Mundy Nozzle Torque Speed % Increase Torque Speed 0 10. 75 0 16. 125 240 0 307 0 X-Stream Team - Design Review Torque 27. 92% 50. 00% 11/6/2020
New nozzle design 11 X-Stream Team - Design Review 11/6/2020
Pulley and Gear Lab Results • The big pulley has an • • OD of 13. 75 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 12 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. 73 5 197. 13 1122. 3 5. 69 6 198. 22 1132. 6 5. 71 X-Stream Team - Design Review Average: 5. 70 11/6/2020
Belt Drive Systems • 4. 5% power loss from existing v-belt system – Slippage – Thermal expansion • Cog belt system 100% efficient 13 X-Stream Team - Design Review 11/6/2020
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. • 14 X-Stream Team - Design Review 11/6/2020
Impedance Matching • For max power transfer from a source to a load, the source impedance must equal the complex conjugate of the load impedance Rs + j. Xs = RL - j. X – 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 15 X-Stream Team - Design Review 11/6/2020
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 16 X-Stream Team - Design Review 11/6/2020
Budget 17 X-Stream Team - Design Review 11/6/2020
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 18 X-Stream Team - Design Review 11/6/2020
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. 19 X-Stream Team - Design Review 11/6/2020
Questions? 20 X-Stream Team - Design Review 11/6/2020
- Slides: 20
