Detailed Design Review P11451

Cook Stove Test Stand GroupFebruary 4th 2011

David Sam (ME)Huseyin Zorba (ISE)Phillip Amsler (ME)

Agenda• Project Inputs• Bill of Materials• Modifications to Test Stand• Project Outputs• Issues

DESIGN INPUTS

Customer NeedsRevision #: 3

Customer Need # Importance Description Comments/Status

CN1 1 Accurate Statistical Results:Repeatable results, minimize variability and quantify uncertainty

Main customer need, by minimizing variability we can achieve repeatable results and quantify our uncertainty.

CN2 1 Develop and document standardized water boil test Document a water boil test or modified water boil test with a test procedure and user manual.

CN3 1 Develop and document standardized quick stove test

Create and document a quick stove test procedure for teams to test variations with instant feedback. By changing one input, user should be able to identify the impact in the output. This test should have a user manual.

CN4 1 Develop and document a field like test

Create and document a test procedure to test the stove under Haitian cooking style which may include longer time to boil. Procedure should be documented with a user manual.

CN5 1 Measure efficiency and it's uncertainty Measure the efficiency of the thermal versus chemical energy used.

CN6 1 Safety Test stand should be safe to operate for untrained users.

CN7 1 Benchmark against other stoves

Test and compare our stove versus rebar stove or another kind of stove under same test conditions. This will allow comparison of results such as fuel usage, emissions, and time to boil

CN8 1 Quantify emissions Greenhouse gases such as CO.

CN9 2 Quantify particulate matter Any solid matter output from the stove into the surrounding environment.

CN10 2 Durable Test stand should be durable and able to withstand years of testing

CN11 2 Ease of use Test stand should be ergonomic and easily used by one user. Also testing should be easily performed by an untrained user.

CN12 2 Easily transportable Test stand should be easily transportable by one user

Engineering SpecificationsRevision #: 3Engr. Spec.

# Importance Source Specification (description) Unit of Measure

MarginalValue

Ideal Value Comments/Status

ES1 1

CN1, CN2, CN3, CN4,

CN7Repeatable time to boil Standard

deviation (%) <20% <10% Boiling time (mins) is an output of the WBT and customer need is to have these results be repeatable and to minimize variability

ES2 1

CN1, CN2, CN3, CN4,

CN7

Repeatable specific fuel consumption

Standard deviation (%) <20% <10%

Ratio of total amount of fuel (wood or charcoal) used to the amount of water (grams fuel/ grams of water) from WBT; this is a specification that can be used in benchmarking.

ES3 1

CN1, CN2, CN3,CN4, CN5, CN7

Repeatable thermal efficiency of stove

Coefficient of Variation (%) <20% <10%

Ratio of the work done by heating and evaporating water to the energy consumed by the fuel source. The thermal efficiency should be repeatable to ensure validity of testing.

ES4 1

CN1, CN2,CN3, CN4 CN7

Repeatable fuel rate consumption

Standard deviation (%) <10% <5%

Fuel rate consumption (g/min), by obtaining repeatable results, we can observe the differences in setting up the fuel source and lighting procedure to help us determine the best method and which is conserve fuel the best. Fuel consumption is defined as the amount of fuel to produce a unit output. (How much fuel to boil water)

ES5 1

CN1, CN2, CN3, CN4,

CN7

Repeatable firepower Standard deviation (%) <10% <5%

Firepower (Watts) is the rate of fuel energy consumed by the stove per minute which can give us the power output of the stove in watts. This can be calculated from WBT data and could also be useful benchmarking.

ES6 1

CN1, CN2, CN3, CN4, CN7, CN8

Accurate emission measurements

Std Dev g (grams)

<2.0 grams

< 1.0 grams

Based on Aprovecho WBT emission performance testing, cook stoves should emit less than 20 grams of CO and most forced air stoves emit less than 10 grams so we will look for a std dev less than 10%. (<2.0 grams)

ES7 1 CN6, CN10Number of accidents # Accidents 1 out of

30 tests 0Accidents relating to any burns, cuts, and shock should be zero for maximum safety during a standard WBT or any other test. This test stand must be safe for general use.

ES8 1CN2, CN3, CN4, CN8

User manual ease # Questions <3 0Through documentation, any user should be able to read and set up the test stand and perform testing without any questions. User manual should include detailed pictures and explanations.

ES9 2

CN1, CN2, CN3, CN4, CN7, CN9

Accurate particulate measurements Std Dev (mg) <150 mg <50 mg

Based on Aprovecho WBT emission performance testing, cook stoves should emit less than 1500 grams of particulate matter so we will be looking for a std dev less than 10% (<150 mg)

ES10 2CN11CN12

Set up time minutes <20 < 10Related to ease of use, set up time for any single user should not take longer than 20 minutes. Goal would be 10 minutes from transporting stand and equipment to loading fuel and lighting fuel by one user.

System Level Work

InputsTest Standards

a)Charcoalb)Stove (Any Kind)c)Test Type (Short, Relevant, WBT)d)Lighting Technique

SYSTEM

Outputsa)Emissionsb)Solid Wastesc)Test Timed)Efficiencye)Statistical Accuracy

System Level Work

Improvement Assessment

Change in Design Waste Management

Impact Assessment

Ecological Health

Inventory

Quantify:Raw Material,Energy,Waste Perform the Test

Goal

Project Scope

Fish Bone

Risk List

Integrated Test Strategy

• Performed 1 Comparison Test – Boiling Times were found for 3 different stoves

• The data outputs are shared among PM’s• New Tests are scheduled for the following days

– Flow Rate– Skirt Size– Pot Shape

Bill of Materials

DESIGN OUTPUTS

Proposed Test Stand

Modifications on Test Stand

SET-UP TIME≈ 5 MINUTES

Modifications for Measurement

• OLD • NEW

Modifications for Measurement

OLD

NEW

Improved Functionality

• New thermocouple mount – New steel mount to replace previous wooden

mount. Mount is also insulated to reduce impact of ambient temperatures on water temperature readings.

• Test stand now has two handles and larger wheels to provide easier transportation. – Test stand can be transported by one user and is

very durable.

Improved Mass Measurements

• By sealing openings in the bottom of the test stand, “noise” in mass measurements have been improved. The impact of wind has a substantially smaller impact on the test stand. Mass measurements from Stovetec stove support the test stand improvements.

Installation of CO monitor

• New monitor has been installed in the exhaust stream of the test stand.

• It allows USB interface to recover data instead of burdening tester with recording data every minute.

Design Calculations

Convective Heat Transfer

Stove

q

q

q

• Assume Stove is a cylinder D~15”, H~20”A=.6m2

• h (air free convection) range 5-10 W/m2K – Use 10 for conservative value

• Ts~600°C• T∞ range -10°C to 30°C

• q=h*A*(Ts-T∞)• Hot q=3420W• Cold q=3660W• Δq =240W or ~5% of total output of

stove (using 5kW output)

• Use area and temperatures from previous– Ts~600°C=873K– T∞ range -10°C to 30°C=263K to 303K– A=.6m2

• Assume Steel (ξ=.07)• q=σ*ξ*A*(Ts

4-T∞4)

– σ=5.6703E-8 W/m2K4

• Hot q=1363W• Cold q=1372W• Δq=9W or ~.2% of total output of stove

(using 5kW output)

Radiation Heat Transfer

Stove

q

q

q

Turbulent Air Flow

Distance Air Velocity 1 Air Velocity 2 Air Velocity 3 Average Air V Dist (r)(in) (ft/min) (ft/min) (ft/min) (ft/min) (ft)

0 977.7 -0.250.5 999 1091 952 1014.0 -0.20833

1 1062 1056 1033 1050.3 -0.166671.5 1131 1059 1056 1082.0 -0.125

2 1074 1025 1022 1040.3 -0.083332.5 1076 1007 1025 1036.0 -0.04167

3 1064 1027 1011 1034.0 03.5 1054 992 1025 1023.7 0.041667

4 1053 986 1027 1022.0 0.0833334.5 1074 1026 1026 1042.0 0.125

5 1124 1016 1041 1060.3 0.1666675.5 990 1001 1019 1003.3 0.208333

6 946.3 0.25

*inert picture of Anemometer in Chimney

Turbulent Air Flow Cont.

0

200

400

600

800

1000

1200

Flow Rate

Air Velocity 1

Air Velocity 2

Air Velocity 3

Average Air V

Average Vel

Distance from Center (ft)

Flui

d Ve

locit

y (ft

/min

)

Volumetric Flow Calculation

Ring Velocity (ft/min) dA ft2 Flow CFM1 985 0.0600 59.122 1032 0.0491 50.663 1059 0.0382 40.424 1047 0.0273 28.545 1031 0.0164 16.866 1031 0.0055 5.62

SUM 201

Numerical Integration Uniform Flow Assumption

Average Vel 1037 ft/minStdDev 22.0 ft/minArea 0.196 ft^2

Flow Rate 204 CFMMin 199 CFMMax 208 CFM

CO Output

0 0.5 1 1.5 2 2.50

102030405060708090

100

CO (ppm) vs Time (not actual data)

Time (min)

Co (p

pm)

dA

– When given ppm vs. time take integral using differential area with trapezoid method.

CO continued

• After integrating and taking sum of differential areas, then units = ppm*min

• Using standard air 1ppm CO=1.23mg CO per m3 air.– ppm is a mass concentration of CO compared

to the fluid it is in.• Finally convert 204 CFM to 5.777 m3 /min• Then

dA

dt

d(pp

m)

min]/[777.5*][

]/[23.1*min]*[][ 33

airmppm

airmmgCOppmAreaCOm

Analysis

CO

CO

• In a water boil test, CO emissions should be lowest during the simmer phase, however during these three tests there is a spike or “noise” during the simmer phase in all three instances. – Hypothesis– Charcoal is shifting position during the simmer

phase, creating abnormalities in CO emissions.– Test – Place stove in test stand and record emission data for

Stovetec stove during combustion without pot of water. Every five minutes, stir charcoal around in stove and after recovering CO data from logger, determine if at every 5 minute interval there was a significant shift in CO emissions.

Water Temperature

Water• When boiling water, a temperature between 99-100 oC

should be reached to accurately determine boiling point.– Hypothesis – cold ambient temperature is impacting the

thermocouple’s accuracy when collecting temperature data. The thermocouple can be modeled as a fin as heat is lost from the tip of the wire inserted into the water to the base of the thermocouple where temperature is read.

– Test – With new insulated thermocouple, boil a pot of water and move the thermocouple to various locations in the pot, not just the center of the pot and observe any differences in temperature. Also note if water actually reaches 100 oC against a non-insulated thermocouple.

Weight-Before

Weight-After

Combined Data

Efficiency

Data Comparison

Issues

Particulate MatterOptical Light Scattering Monitoring Method• Most accurate way to test emissions

through light scattering monitors. Data can be benchmarked and compared with published water boil data from established laboratories.

• Can provide real-time results, used to analyze particulate emissions during each phase of the water boil test.

• Very expensive and systems can be very fragile.

• Depending on light scattering device, may need to take passive measurements through sampling air from the exhaust stream.

Gravimetric Pump and Filter Method

• Through a gravimetric pump, particulate matter from a sample of the air stream is collected onto a filter.

• Filter is tared before measurements occur and then weighed after to obtain a total particulate mass measurement for a whole water boil test.

• Does not provide real time results and difficult to set up a system to determine emissions during different phases of testing.

• Tends to be more of a quantitative test, comparing one stove to another within our own test stand instead of benchmarking against published data.

Light Scattering Method

• Sensidyne Nephelometer

• Provides real time results

• Data logging, internal pump, selective sample rates

• Operating temperature, 0 – 50 Celsius

• $2,750.00

Gravimetric Pump and Filter Method

• Airmetrics MiniVol Users Guide

• Create a sample stream from exhaust and measure PM emissions

• Weigh the PM collected onto filters

• Quantitative method to compare stove emissions within our own test stand

Particulate Matter Testing• Optical Light Scattering Monitoring Method

– Most accurate way to test emissions through light scattering monitors. Data can be benchmarked and compared with published water boil data from established laboratories.

– Can provide real-time results, used to analyze particulate emissions during each phase of the water boil test.

– Very expensive and systems can be very fragile.– Depending on light scattering device, may need to take passive measurements through sampling

air from the exhaust stream.

• Gravimetric Pump and Filter Method– Through a gravimetric pump, particulate matter from a sample of the air stream is collected onto

a filter.– Filter is tared before measurements occur and then weighed after to obtain a total particulate

mass measurement for a whole water boil test.– Does not provide real time results and difficult to set up a system to determine emissions during

different phases of testing.– Tends to be more of a quantitative test, comparing one stove to another within our own test stand

instead of benchmarking against published data.

Error Testing and Benchmarking

• Test a range of stoves to get an idea of variability from wind, humidity, stove size, temperature, and other variabilitys.

• Test other stoves (i.e.. Rebar) for emissions– Compare to published WBT data– Check if test stand has systematic or arbitrary errors

• If test is successfully repeatable then we will know how the P11461 stove compares.

Questions?