Embed Size (px)
Citation preview
The Water Boiling Test (WBT)
withISO/IWA Metrics
andARC Equipment
July 30, 2012
Stove Camp
Updated by Abraham Mooney
The Water Boiling Test (WBT)
Standardized, reproducible lab test Boil and simmer water Measure the boil time, fuel use, efficiency, emissions Trained tester carefully tends the fire (COV) High and low power test phases Cold stove and hot stove test phases Allows for multiple pots on one stove
Stove Testing Continuum
WBT
CCT
KPT
Increasing costIncreasing sample size and variabilityIncreasing measurement of in-home useIncreasing relation to WHO air quality guidelines
Increasing control of variablesIncreasing isolation of stove performanceIncreasing quantification of emissionsIncreasing intervention of testersLab
Field
Purpose of WBT
Effective design tool to evaluate design changes of a stove
Stove Improvement through comparison (High Accuracy equip.)
Advantages of the WBT
Reproducible, standardized
Stoves from around the world can be compared
Stove design changes observed clearly and quickly
Benchmark evaluation and comparison
Disadvantages of the WBT
Not always reproducible Fuel irregularities, and “to error is human.”
Not representative of field useOnly one simulated cooking task
Hard to do for some stovesBatch-loading stoves: TLUD’s, charcoal
WBT Procedure
Phase COLD START
HOT START
SIMMER
Task Bring to Boil 5L in first pot
Bring to Boil fresh 5L in first pot
Simmer remaining 5L for 45 minutes
Record TimeFuelWater Charcoal
TimeFuelWater*Assume Same Charcoal as Cold Start*
Time FuelWaterCharcoal
WBT Procedure
Time
WaterTemperature
Tboil
Troom
Tboil-6degC
Fresh Water
COLD STARTHOT START
45 min. SIMMER
WBT – Preparing for the Test
First do a practice test to:
• Get familiar with the stove• Determine if the stove should be tested
with 2.5 or 5 liters• How much fuel is required?• Boiling temperature of water (local)?
WBT – Preparing for the Test
1. Scale - 6000g range, 1g resolution
2. Temperature sensor – waterproof
3. Fixture for suspending temperature sensor
4. Wood moisture meter or oven for fuel MC
Gather Supplies
WBT – Preparing for the Test
5. Timer or watch6. Pot – standard or dedicated, no lid7. Heat resistant pad for scale8. Charcoal scooper/tongs9. Char tray10. Heat resistant gloves11. Water – room temp,
- at least 10 liters12. Fuel – air dried, uniform
- 2 bundles ~ 2kg each
Gather Supplies
WBT – Conducting the Test
Phase 1: High Power Cold Start
• Set the pots on the stove with 5000g of water with the temp sensor suspended in the water of Pot 1.
• Record:
-Starting weight of pots with water-Starting water temperatures-Initial mass of the bundle of fuel
• Light the fire - record start time
• Tend fire and bring water to a boil
WBT – Conducting the Test
Phase 1: High Power Cold Start
• When Pot 1 boils record:
time
temperature of all pots
pot plus water weights
fuel remaining
• break char off tips of burned sticks
• Put char on tray and record weight of char plus tray
WBT – Conducting the Test
Phase 2: High Power Hot Start
• Refill the pots with cool water and repeat the boil procedure starting with a hot stove
• Use a new bundle of wood
• This time, when Pot 1 boils keep the char in the combustion chamber. DO NOT WEIGH THE CHAR
• Weigh the pots and place them back on the stove
• Weigh the wood, place it back in the combustion chamber, then re-light it.
WBT – Conducting the TestPhase 3: Low Power Simmer
• Record the start time once the fire is lit
• Transfer over the fuel weight, pot and water weights, and water temp from the results column at the end of the hot start
• Tend the fire to keep the water temp of the pot at 3-6 degrees C below boiling for 45 min
• After 45 min of simmer record:
Final water temperature Weight of Pot 1 plus water Final weight of fuel and
char remaining
Three test phases, real-time
measurement(CO2, CO, PM)
WBT Results
THE NEW DEAL
WBT Results
Thermal Efficiency (%)
100
High efficiency ≠ low fuel consumption
because high power stoves evaporate lots of water and also use lots of fuel
*IWA Metric
WBT Results
Low Power Specific Consumption (MJ/min/L)
*IWA Metric
¿𝐸𝑛𝑒𝑟𝑔𝑦 𝑟𝑒𝑙𝑒𝑎𝑠𝑒𝑑 𝑓𝑟𝑜𝑚𝑤𝑜𝑜𝑑
(𝑇𝑖𝑚𝑒𝑠𝑖𝑚𝑚𝑒𝑟 ) 𝑥(𝑊𝑎𝑡𝑒𝑟 𝑅𝑒𝑚𝑎𝑖𝑛𝑖𝑛𝑔)
WBT Results
High Power CO (g/MJd)
*IWA Metrics
¿𝐶𝑂
𝐸𝑛𝑒𝑟𝑔𝑦𝑑𝑒𝑙𝑖𝑣𝑒𝑟𝑒𝑑𝑡𝑜𝑝𝑜𝑡
Low Power CO (g/min/L) ¿𝐶𝑂
(𝑇𝑖𝑚𝑒 )𝑥 (𝑊𝑎𝑡𝑒𝑟 𝑅𝑒𝑚𝑎𝑖𝑛𝑖𝑛𝑔)
WBT Results
High Power PM (mg/MJd) ¿𝑃𝑀
𝐸𝑛𝑒𝑟𝑔𝑦𝑑𝑒𝑙𝑖𝑣𝑒𝑟𝑒𝑑𝑡𝑜𝑝𝑜𝑡
Low Power PM (mg/min/L) ¿𝑃𝑀
(𝑇𝑖𝑚𝑒 )𝑥 (𝑊𝑎𝑡𝑒𝑟 𝑅𝑒𝑚𝑎𝑖𝑛𝑖𝑛𝑔)
*IWA Metrics
WBT Results
*IWA Metrics
Indoor Emissions CO (g/min)
¿𝐶𝑂𝑇𝑖𝑚𝑒
Indoor Emissions PM (mg/min) ¿
𝑃𝑀𝑇𝑖𝑚𝑒
WBT Results
Temperature Corrected Specific Fuel Consumption (g/L)
¿ 75𝑇 𝑏𝑜𝑖𝑙−𝑇 𝑖𝑛𝑖𝑡
∗𝑒𝑞𝑣𝑖𝑣𝑎𝑙𝑒𝑛𝑡 𝑑𝑟𝑦𝑤𝑜𝑜𝑑𝑐𝑜𝑛𝑠𝑢𝑚𝑒𝑑 (𝑔)
𝑙𝑖𝑡𝑒𝑟𝑠𝑜𝑓 𝑤𝑎𝑡𝑒𝑟 𝑟𝑒𝑚𝑎𝑖𝑛𝑖𝑛𝑔(𝐿)
= dry wood mass – -- equivalent mass of
wood stored as char
wood mass that was consumed to
evaporate the moisture in the
wood
Eq. dry wood consumed
Best indicator of fuel consumption
WBT Results
Average Firepower (W)
¿𝑡𝑜𝑡𝑎𝑙𝑒𝑛𝑒𝑟𝑔𝑦 𝑟𝑒𝑙𝑒𝑎𝑠𝑒𝑑𝑏𝑦 𝑓𝑢𝑒𝑙𝑑𝑢𝑟𝑖𝑛𝑔 h𝑡 𝑒 𝑡𝑒𝑠𝑡𝑝𝑒𝑟𝑖𝑜𝑑 ( 𝐽𝑜𝑢𝑙𝑒𝑠)
h𝑙𝑒𝑛𝑔𝑡 𝑜𝑓 𝑡𝑒𝑠𝑡𝑝𝑒𝑟𝑖𝑜𝑑 (𝑠𝑒𝑐𝑜𝑛𝑑𝑠)
How big is your stove
WBT Results
Turndown Ratio
¿𝑎𝑣𝑒𝑟𝑎𝑔𝑒𝑏𝑜𝑖𝑙 𝑓𝑖𝑟𝑒𝑝𝑜𝑤𝑒𝑟 (𝑊 )
𝑎𝑣𝑒𝑟𝑎𝑔𝑒𝑠𝑖𝑚𝑚𝑒𝑟 𝑓𝑖𝑟𝑒𝑝𝑜𝑤𝑒𝑟 (𝑊 )
WBT Sample Size At least three full tests per stove design are recommended
Then do more tests if necessary to achieve the desired statistical significance measured by the COV (Coefficient of Variation)
COV is a measure of how much your results vary COV indicates how good you are at getting repeatable results
For stove testing COV = 5% is very good
COV = 10% or 25% is also acceptable
Aprovecho Emissions Equipment
PEMS & LEMS
Portable (or Lab)
Emissions Measuring System
IAP Meter
Indoor Air Pollution Meter
PEMS Collection hood collects stove emissions Sensor box measures:
1. CO 2. CO23. PM (laser)4. Flow rate in duct5. Temp in duct6. Pot temp
Uses:1. Measure stove emissions (WBT, CCT) 2. Stove design tool
PM Sensor: Scattering PhotometerPEMS
CO Sensor: Electrochemical Cell
Diagram Courtesy Monox
PEMS
CO2 Sensor: NDIRPEMS
PEMS Data Processing Software
Outputs include: Graph of emissions vs. time Standard performance measures Specific fuel consumption (grams/liter) Total emissions (grams) Specific Emissions (grams/liter) Emissions Factors (grams/kg fuel) Efficiency and Firepower
PEMS
LEMS and Gravimetric
Why use gravimetric?
Photometer: Estimates the REAL TIME mass concentration of particulate matter from optical measurements
Gravimetric: Measures total mass concentration of particulate matter, at end of test (scale c10^-5 g).
LEMS
With gravimetric we move to…Categorization studies(e.g. Tier 4)
Laser vs. gravimetric Photometer Output = scattering coefficient (1/m) Physical meaning: fraction of light scattered away for every meter a light beam travels
PEMS
Mass concentration estimated by:
Indoor Air Pollution Meter
• Measures concentrations of:• CO (Carbon Monoxide)• PM (Particulate Matter)
• Uses:• Measure room concentration• Measure personal exposure
• wear meter in backpack with sample tube• CCT, KPT, other comparative tests
• Stores data on SD Memory Card
Why use gravimetric? Gravimetric
Particles are collected on a filter and weighed.
PEMS
PM Sensor: Scattering Photometer(same as PEMS)
Indoor Air Pollution Meter
CO Sensor: Electrochemical Cell(Also used in PEMS)
Diagram Courtesy Monox
Indoor Air Pollution Meter
Features Sample speed selection
Fast: Every 10 secondsBattery life: 3 days
Medium: Every 1 minuteBattery life: 2 weeks
Slow: Every 10 minutesBattery life: 1 month
LED indicates meter is on Serial port for live graphing
Indoor Air Pollution Meter
Data Processing Software
Outputs include: Graph of emissions vs time Average concentrations Maximum and minimum concentrations 15 minute average concentrations
IAP Meter
Summary
PEMS Measures emissions:
CO, PM, and CO2 Stove total emissions
Measures pot temp for WBT
Cost: $10,000 USD
IAP Meter Measures emissions:
CO and PM Room concentrations
and personal exposure
Cost: $2,400 USD
More Information
www.aprovecho.org
• Spec sheets• Brochures• Manuals• Data processing spreadsheets
Documentation
www.aprovecho.org/lab/pubs/testing
Download testing protocols
