Making Graywater Green:

Transcription

1 Making Graywater Green:

2 Engineering a Micro Hydroelectric Generator

3 ENGINEERING PROBLEM Clean energy has the potential to reduce carbon emissions. However, small-scale hydropower in household pipes is underutilized because existing devices are inefficient.

4 ENGINEERING GOALS The goal of this project is to engineer a micro hydroelectric generator for use in graywater pipes that is low cost, can generate low voltages of power, and does not significantly decrease average water flow rate.

5 BACKGROUND Hydropower is a reliable way to obtain clean energy, depending solely on the energy of water to spin an impeller and generate electricity. The kinetic energy of flowing or falling water, when it hits the blades of a waterwheel or impeller, becomes rotational energy. A generator is then utilized to convert the mechanical energy to electrical energy, which can further be stored in batteries, capacitors, or other electrical energy storage devices, and used as needed.

6 PROCESS Five impeller models and an adaptive testing apparatus were designed in CAD and 3D printed. The blades of the five models were analyzed using fluid flow simulations to help hypothesize which would give the best results. The prototypes were tested in the real-world to determine voltage output and impact on water flow rate. For testing, a model including an Arduino water flow sensor was used to ensure water flow rate remained relatively constant among trials.

7 MATERIALS Table 1: The materials and computer programs utilized for the project. Item/Program: Quantity: Obtained From: Ball Bearings 2 Parent Arduino Mega 2560 w/ Starter Kit 1 MicroCenter Hall-Effect Water Flow Meter 1 Gather-Special (through Amazon) 0.5 and 1.5 Tubing N/A Home Depot Bolts 4 Parent MakerBot Print (Program) 1 Makerbot.com SOLIDWORKS 2017 (Program) 1 through WPI Onshape (Web-based program) 1 Cad.onshape.com Hall-Effect Flowmeter Arduino Code 1 Arvind Sanjeev of DIYhacking.com V GLE2016 DC Motor 1 WireFactory (through Amazon) Arduino (Program) 1 Arduino.cc Multimeter 1 Parent MakerBot 3D Printer 1 MAMS Bucket 1 Parent Fritzing (Program) 1 Fritzing.org Water Flow Sensor Figure (for Fritzing) 1 Omnigatherum.ca/wp/?p=87

8 VOLTAGE (V) RESULTS A B C D E IMPELLER Figure 4: A bar graph with the average maximum voltage for each impeller.

9 Figure 3: Front, Isometric, and Bottom view of Impeller B, made with Onshape.

10 Table 2: Voltage Testing Summary Data Water Flow Rate Maximum Voltage Impeller. (ml/s) (V) A B C D E Table 3: Inlet Flow Time Versus Outlet Flow Time in seconds for each prototype. Inlet Flow Outlet Flow Impeller. (s) (s) A. 4 4 B. 4 4 C. 4 4 D. 4 4 E. 4 4

11 Figure 2: Adaptive Impeller Holder Drawing. Dimensions in inches. Created in Onshape.

12 ENGINEERING MATRIX Table 4: An engineering matrix with weighted criteria, and each impellers ranking among each of the criteria. Impeller Criteria: Weight: A B C D E Low Cost Generates Low Voltages Does Not Significantly Increase Flow Time Total:

13 DATA ANALYSIS The data was checked for outliers. Voltage outputs were compared in an ANOVA; all of the impellers had significantly different voltage outputs from one another. Differences in flow times were compared using paired t-tests; none of the impellers significantly slowed flow time. An engineering matrix was used in conjunction with these methods to determine the optimum design.

14 The impellers received the same score for low cost because they were all 3D printed from the same material, and the differences between their masses were negligible. Scores for voltage output were based on ranges; less than 0.15 volts received a one, 0.15 to 0.25 received a two etc. None of the prototypes significantly decreased the flow rate of the water, so all five received the same score for that criterion. For the total score, the respective impeller s score in each category was multiplied by the category s weight. The weighted scores per impeller for each criterion were added to give that prototype s total score.

15 CONCLUSION Impeller B, with an average maximum voltage output of volts at an average maximum water flow rate of 162 ml/s, was determined to be the best of the five prototypes, as it matched all three criteria and had the highest significantly different (p = ) power output.

16 DISCUSSION The engineered device is a low-cost, effective way to generate small amounts of clean energy. The prototype allows a user to generate electricity passively, without significantly reducing water flow. With future extensions applied, the device would allow a consumer to store electricity for later use, and reduce one s need for conventional batteries

17 FUTURE EXTENSIONS Test different materials for impellers to increase durability and performance. Utilize an automated water release system which senses when to release a predetermined volume of water. Add a debris filter to prevent debris from getting stuck in the impeller. Test energy storage techniques such as capacitors and rechargeable batteries. Gear the motor to increase RPM and therefore theoretically increase voltage output. Figure 4: Future Extensions