06411 Mini Nucleating Bubble Engine

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 (mm) 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 Objectives • Size limitations – 1 ft3 • Cost • mm scale • Regulate the heater via a control system • Battery or power supply operated • Standard sized battery • Voltage 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 Model • System models

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

5. Risk Assessment Major Project Risks • Engine parts could be too unique and small • May result in going over budget • May 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. Morphological Chart

8. Concept Feasibility Weighted Average Analysis

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

10. Detailed Design Material Selection • Piston Casing • Boroscilicate Glass (Pyrex) • Stock part at McMaster - Carr • Machining - glass department is able to cut • Piston Base • Glass Mica Ceramic – high temp • Machining - Mechanical engineering machine shop • Piston • Low Density Polyethylene (LDPE) • Less dense than water • Core center to promote floatation • Machining - Mechanical Engineering machine shop • Electrodes • Copper Wire - Stock item at McMaster-Carr • Heater Element • Option 1 • Platinum wire and soldered electrodes • Option 2 • Manufactured 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 velocity • Pipe Flow with Gravity

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

15. Theoretical Models 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

16. xp B2 mp Piston B1 xw K1 B4 Water mw B3 Theoretical Models 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

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

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

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

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

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

25. Testing Experimental Design • Accurate high speed video analysis • Precision scale • A high intensity light for maximum resolution • Equipment • Camera: Photron Ultima APX digital video • Lens: Nikon AF Micro NIKKOR 105mm 1:2.8 D with optional 2x magnification. • Light: 600 watt halogen continuous source • Fan: High CCM 24 volt • Scale: Stainless, + .01 mm • Camera mount: standard x-y mount • Base: 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-up • MATLAB Simulations • Bubble growth • Piston movement