1. 06411 Mini Nucleating Bubble Engine Steven Nathenson Joseph Pawelski Joaquin Pelaez Andrew Pionessa Brian Thomson

2. Project Overview Project Description –Creation of a mini device (mm scale) that harnesses the energy from periodic vapor bubble formation (nucleation) in a fluid resulting from heating –Current research MEMS devices use a micro scale (  m) piezoelectric membrane to convert mechanical oscillations from bubble nucleation directly to electrical current. –Project focuses on the development of a slightly larger (mini) scale engine permitting greater experimental analysis capability in addition to implementation in applications requiring mechanical energy. –Periodic bubble nucleation is produced by a mini heater powered by a modulated power supply.

3. Needs Assessment Design ObjectivesDesign Objectives –Size limitations – 1 ft 3 –Cost –mm scale –Regulate the heater via a control system –Battery or power supply operated Standard sized batteryStandard sized battery Voltage and amperage based upon the power requirements of heaterVoltage and amperage based upon the power requirements of heater –What type of fluid allows for the best bubble growth? –Create a light weight system –Successfully test device –Benchmark efficiency of engine –Bubble visualization with high speed camera Develop Theoretical ModelDevelop Theoretical Model –System models

4. Technical Requirements Performance RequirementsPerformance Requirements –Mechanical oscillation greater than 5-10 Hz –Run time of 20 seconds or more Functional RequirementsFunctional Requirements –Bulk fluid temperature –Bubble growth surface Yield the appropriate amount of bubbles from the heating surfaceYield the appropriate amount of bubbles from the heating surface –Minimize friction to Increase efficiencyIncrease efficiency Accurate bubble modelAccurate bubble model

5. Risk Assessment Major Project Risks –Engine parts could be too unique and small May result in going over budgetMay result in going over budget May result in lack of timeMay result in lack of time –The engine design may be to similar to current MEMS devices if a piston or piston like design is not utilized –Bubbles may be too small to move the piston a significant amount for testing

6. Gantt Chart

7. AttributeOption 1Option 2Option 3Option 4Option 5Option 6 Engine TypeBuoyant piston Partially Submerged piston Submerged cantilever beam Non-submerged cantilever beam Rotary w/ ndent Rotary w/ Volume change Liquid Type De-ionized water AlcoholOther------------------------- Impact PlateResistant wireProtective plateOther------------------------- Power Supply DC power supply DC batteryAC power supply------------------------- Heating Element Straight wireSquare wireCircular wireConcentric wireMetal plate------------ Control System Stamp controller ASIC chip Other programmable chip ------------------------- Cooling System NoneFluid reservoirHeat exchanger------------------------- Movement Causality Bubble Impact Boiling & Condensation ------------------------------------------ Electrical System Pulse width Modulator (PWM) AC circuit design DC circuit design------------------------- Morphological Chart

8. Concept Feasibility Weighted Average Analysis

9. Design Overview Buoyant Piston DesignBuoyant Piston Design –Expanding bubbles in the water cause piston to move –Piston-cylinder configurations Simple to machineSimple to machine One moving partOne moving part –Movement of piston easily measured –Piston is buoyant Seal is not crucial and may leak slightlySeal is not crucial and may leak slightly Friction is reducedFriction is reduced

10. Detailed Design Material Selection Piston CasingPiston Casing –Boroscilicate Glass (Pyrex) –Stock part at McMaster - Carr –Machining - glass department is able to cut Piston BasePiston Base –Glass Mica Ceramic – high temp –Machining - Mechanical engineering machine shop PistonPiston –Low Density Polyethylene (LDPE) –Less dense than water –Core center to promote floatation –Machining - Mechanical Engineering machine shop ElectrodesElectrodes –Copper Wire - Stock item at McMaster-Carr Heater ElementHeater Element –Option 1 Platinum wire and soldered electrodesPlatinum wire and soldered electrodes –Option 2 Manufactured heating elements provided by Dr. KandlikarManufactured heating elements provided by Dr. Kandlikar

11. Piston Design Piston Considerations –Max volume of piston given density of water & piston material –Obtain wall thickness –Obtain true piston volume given drill bit dimensions –Verify that the piston still floats at appropriate height

12. Budget $500 –Piston –Casing –Base –Heater –Electrical Controls

13. Theoretical Models Navier Stokes –Parallel Plates with Gravity Upper plate is moving at a constant velocityUpper plate is moving at a constant velocity –Pipe Flow with Gravity

14. Theoretical Models System Models –Factors taken into account –Two model types Based upon geometrical relationshipsBased upon geometrical relationships Based directly off of the Navier-Stokes equationsBased directly off of the Navier-Stokes equations –5 total models Some neglected forces shown to be insignificantSome neglected forces shown to be insignificant Some include all forces of the systemSome include all forces of the system –Verification Model Simplified version of the modelsSimplified version of the models

15. Systems Model 1 –Second order approximation –Negligible forces are removed to simplify the systems model –Model is setup for a known water displacement –Model assumes that the water moves proportional to the l displacement of the bubble Theoretical Models

16. B1B1 B2B2 B4B4 xpxp xwxw mpmp mwmw B3B3 K1K1 Water Piston Systems Model 2 –First order approximation –Neglects the viscous shear force due to the air on the piston –Model assumes that the water moves proportional to the l displacement of the bubble Theoretical Models

17. Plot comparison from Simulink Models –Negligible factors in design considerations Figure 15: Piston acceleration Theoretical Models

18. Additional Theoretical Analysis Bubble growth rate –Mikic’s equations –Experimentally determine with high speed camera

19. Additional Theoretical Analysis Heat TransferHeat Transfer –Transient heat conduction –Semi-infinite solid 10 ms x qo”qo” T ∞ = 25 C T s = 400 C

20. Electrical System Requirements Specifications –Supply pulse signal with adjustable amplitude, duty cycle, and frequency –Signal must be output continuously –100, 72, and 60 W signal for 10, 20 and 30 ms pulse –Implement component protection as well as operator protection –Design for small load resistance (~0.5 Ω) –Flexible for different loads

21. Specific Electrical Requirements Load Power, P L [W] Pulse Width, PW [ms] Input Voltage, Vin [V] Current, I [A] 100107.1814.142 72206.0912 60305.5610.956

22. Electrical System Concepts

23. Final Electrical Design (a) Single NMOS(b) Single PMOS(c) Combined Current for saturation condition

24. Final Electrical Design Results Input Voltage, Vin [V] Pulse Width, PW [ms] Load Voltage, VL [V] Current, I [A] Load Power, PL [W] Expected Load Power, PL [W] Percent Error [%] 5.65107.094314.189100.658100.658 5.2206.050912.10273.22772 1.7 4.3305.537011.07461.31660 2.2

25. Testing Experimental Design –Accurate high speed video analysis –Precision scale –A high intensity light for maximum resolution –Equipment Camera: Photron Ultima APX digital videoCamera: Photron Ultima APX digital video Lens: Nikon AF Micro NIKKOR 105mm 1:2.8 D with optional 2x magnification.Lens: Nikon AF Micro NIKKOR 105mm 1:2.8 D with optional 2x magnification. Light: 600 watt halogen continuous sourceLight: 600 watt halogen continuous source Fan: High CCM 24 voltFan: High CCM 24 volt Scale: Stainless, +.01 mmScale: Stainless, +.01 mm Camera mount: standard x-y mountCamera mount: standard x-y mount Base: optics tableBase: optics table

26. Preliminary Test Conclusions Problems encountered during preliminary testing –More power is needed –Higher resistance heater –Ability to solder small scale – Micro-e department –Solder to withstand high temperatures –A more stable platform –Formal setup –These details will be worked out in Senior Design II by the senior design team

27. Senior Design II Plan

28. Demonstrations Enlarged mock-upEnlarged mock-up MATLAB SimulationsMATLAB Simulations –Bubble growth –Piston movement