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Cook Stove for Haiti

Cook Stove for Haiti. Project 11461. Detailed Design Review. Date : February 11, 2011 Location: 78:2150 Time: 10:15am – 12:15pm. Team Members. Lead Engineer Jordan Hunter(ME). Team Engineers Alex Seidel (ME) Brian Knight (ME) Mike Lagos (IE). Project Leader Rob Reid (ME).

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Cook Stove for Haiti

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  1. Cook Stove for Haiti Project 11461 Detailed Design Review Date: February 11, 2011 Location: 78:2150 Time: 10:15am – 12:15pm

  2. Team Members Lead Engineer Jordan Hunter(ME) Team Engineers Alex Seidel (ME) Brian Knight (ME) Mike Lagos (IE) Project Leader Rob Reid (ME)

  3. Presentation Overview Project Background Project Overview Customer Needs Assessment Engineering Specifications System Architecture System Integration Risk Assessment Test Plan Flow of Analysis Design Analysis BOM Plan for MSD 2 Traditional Cook Stove

  4. The World Health Organization estimates 3 billion people use biomass cooking regularly. Approx. 1.5 million people die each year from stove emissions Our main focus is the people of Haitiwho’s main method of cookingis open flame stoves, utilizing charcoaland wood. We are partnering with the H.O.P.E. Organization, which works with the Haitian people to help improve theirliving conditions and save lives. H.O.P.E. is working with RIT to create an improved cook stove designwhich is more efficient and lesshazardous to its users. Project Background Image from feaststl.com shows a basic lump charcoal cooking stove

  5. Mission Statement Design and construct all mechanical and structural aspects of a thermoelectric biomass cook stove. The stove will utilize a blower/fan powered by thermo-electrics to significantly increase efficiency and reduce fuel consumption and emissions. In comparison with current Haitian stoves, the project stove will have a reduction in emissions and required fuel of 50% Deliverables • An improved RIT stove design that has been tested and validated using a working prototype. • The improved stove is to reduce fuel use and emissions by more than 50% from traditional Haitian stoves. • Build at least two prototype stoves to be sent to Haiti for field testing. • Detailed project report. • Detailed presentation for Imagine RIT. Project Overview

  6. Customer Needs

  7. Engineering Specifications

  8. System Architecture

  9. Risk Assessment

  10. Risk Assessment

  11. Testing Groups • Non-Operational Testing Group • Operational Testing Group • Non Testing Group • Destructive Testing Group • Untestable Testing Group Testing Plan

  12. Non-Operational Testing NES –Thermoelectrics Connection Test ES4 – Pot Diameter Range Test ES13 – Time to Replace Parts Test ES14 – Stove Volume Test ES15 – Stove Weight Test ES16 – Lifting Index Text ES21 – Assembly Time Test Operational Testing ES1 – Time to Combustion Test ES2 – Time to Boil Water Test ES3 – Range of Heat Output Test ES8 – Tasks to Maintain Combustion Test ES17 – CO Emissions Test ES18 – Hazardous Emissions Test ES19 – Required Fuel to Boil Water Test ES20 – Maximum Temperature Test Testing Plan Non Testing ES6 – Cost to Produce ES7 – Cost to Operate Destructive Testing ES5 – Pot Weight Range Test ES11 – Stove Drop Test Untestable Testing ES9 – Stove Life Test ES10 – Cycles without Cleaning Test ES12 – Corrosion Test

  13. Stove Design Important Dimensions: Stove base Height: 8.5” Radius: 6” Combustion Chamber Height: 6” Radius: 7.25”

  14. Stove Assembly • Made up of 5 Components • Base • Outside combustion chamber shell • Combustion chamber • Top cover • Pot supports

  15. Structural Analysis

  16. - 2 reactions occur in the combustion of charcoal  -- First, a very rapid reaction between Air (Oxygen) and Charcoal (Carbon) to produce CO2 and an extreme amount of heat.  -- Second, a much slower reaction that consumes the charcoal and converts the CO2 into CO while consuming heat.- Emissions should be reduced if full combustion is achieved- The larger the lump charcoal size, the deeper a vertical stove would have to be to ensure complete combustion (If not enough vertical space exists in the heated zone for both reactions to fully occur the charcoal will not be fully burned)- Air Flow should be very close to the base and come in from the side  -- Air flow holes should be circular unless the stove has a very wide inner diameter or has a rectangular base in which cases rectangular holes with the longest side being the horizontal should be used  -- If air holes are used they need to be kept as clean and unblocked as possible- Slower air flows velocities are preferred to ensure full combustion occurs inside of the stove without making it extremely tall/long (There is a certain point where the air flow velocity is too low)- Preheating the air before it first enters will decrease the fuel consumption- All data point to the fact that additional air holes at the top of the stove will not be beneficial in any way.Data from: The mastery and uses of fire in antiquity By J. E. Rehder Combustion

  17. Combustion

  18. Combustion

  19. Combustion

  20. Combustion

  21. Combustion

  22. Combustion

  23. Analysis Process : Combustion Chamber • Heat require to meet specs is calculated • Heat gain to sustain boiling is estimated from heat lost • Combustion chamber spectrum analyzed with various possible efficiencies and charcoal energy contents • Stoichiometric Ratio of the varying charcoals is calculated • Calculated : - Heat Output Range • - Fuel Consumption • - Air Flow • Combustion chamber dimensions calculated from estimated density of charcoal

  24. Charcoal Specs www.fao.org/docrep/x5328e/x5328e0b.htm

  25. Fuel Consumption, Air Flow, & Chamber Size

  26. Fuel Consumption, Air Flow, & Chamber Size

  27. Fuel Consumption vs Time to Complete Boil

  28. Stoichiometric Air Flow vs Time to Complete Boil

  29. Air Flow Analysis • Pressure drops due to • Rapid Expansion when air enters outer stove chamber • Orifice • Charcoal Bed • Annulus • Pressure Rises due to • Head supplied by fan • Heating of air in combustion chamber • Pressure drops through the system are determined to ensure the fan is not supplying more than 1W of power to the air entering the system.

  30. Flow Schematic Annulus Pot & Water Air Flow Air Flow Fan Combustion Packed Bed of Charcoal Orifices

  31. Major Equations

  32. Assumptions • Rapid Expansion coefficient • K=0.85 • Determine from Area ratio=A1/A2 • Used Figure 8.15 in Introduction to Fluid Mechanics by Fox, Pritchard, McDonald • Velocity is determined from fan volumetric flow rate • Orifice has a square edged inlet • K=0.5 from Area Ratio=A2/A1 • a=0.5 • Pressure drop across packed bed of charcoal • Assumed particle size is approximately 1.5”-2.0” • ε (Void Ratio)=Void Volume/Total Volume • Power supplied by fan cannot exceed 1W

  33. Parameters

  34. Spreadsheet Layout

  35. Effects of Varying Orifice Size

  36. Effects of Varying Particle Diameters

  37. A Thermal analysis of the stove system was then completed in order to help understand the affects of different forms of heat transfer. • The key pieces of information needed from this analysis are: • Heat Loss Through stove walls • Surface Temperatures of the various chambers. (Shown to Right) • Affects of different insulations and barriers. • This data would then help us to optimize the stove in terms of heat transfer and minimize thermal loses throughout the stove. Thermal Analysis

  38. Equations Used to Calculate Losses due to Conduction, Convection, and Radiation. Radiation Within Combustion Chamber & To Atmosphere qrad = Ac* ε *σ* (T1^4 – T2^4) [Large Cavity] Radiation Within Annulus qrad = (Ac* σ *(T1^4 – T2^4)) [Annulus] ((1/ε1)+((1-ε2)/ε2)*(r1/r2))   Conduction Within Insulation Layer qcond =(2*Pi*L*K*(T1-T2)) / ln(r2/r1) Convection Within Combustion Chamber, Annulus, & To Atmosphere qconv = h*A*(T1-T2) Energy Lost in Air qforced = mdot*Cp*(T1-T2) Thermal Circuit Diagram Thermal Analysis Ts3 Ts2 Ts1 Tfire Combustion Chamber Air Annulus 1” Ceramic Insulation Blanket

  39. Energy Balances Were used to optimize the system using Excel Solver. Energy Balance Surface 1 qconv-fire + qrad-fire – qconv-annulus1– qrad-12 = 0 Energy Balance Surface 2 qrad-12 + qconv-annulus2 – qcond-ins = 0 Energy Balance Surface 3 qcond-ins + qrad-amb – qconv-amb = 0 Energy Balance Air qconv-annulus1 + qconv-annulus2 – qforced = 0 Thermal Analysis The energy balances were used in conjunction with the heat transfer equations to solve for the air and surface temperatures in and around the stove.

  40. Thermal Analysis • Using the constants to the left, I was able to calculate the approximate surface temperatures. • According to these results we exceed our target spec of having a 50 C outside stove wall (TS3). • These values were found using 1” thick layer of ceramic insulation (L=1”, K=0.29 W/m KL), From Thermal Ceramics Corp. • The inner stove wall is also made of a polished steel, which acts as a radiant barrier.

  41. Insert 1” thick ceramic insulation blanket between combustion chamber and outside wall. • Secondary wall of polished steel to promote fluid flow and act as a radiant barrier. Thermal Analysis Radiation Conduction This combination yields a theoretical total heat loss through the stove walls of ~ 120 W. Convection

  42. BOM

  43. Project Plan

  44. Questions?

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