The Water Boiling Test (WBT ) with ISO/IWA Metrics and ARC Equipment

1. The Water Boiling Test (WBT)withISO/IWA MetricsandARC Equipment July 30, 2012 Stove Camp Updated by Abraham Mooney

2. 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

3. Stove Testing Continuum WBT Increasing control of variables Increasing isolation of stove performance Increasing quantification of emissions Increasing intervention of testers Lab CCT Field Increasing cost Increasing sample size and variability Increasing measurement of in-home use Increasing relation to WHO air quality guidelines KPT

4. Purpose of WBT • Effective design tool to evaluate design changes of a stove • Stove Improvement through comparison (High Accuracy equip.)

5. Advantages of the WBT • Reproducible, standardized • Stoves from around the world can be compared • Stove design changes observed clearly and quickly • Benchmark evaluationand comparison

6. Disadvantages of the WBT • Not always reproducible Fuel irregularities, and “to error is human.” • Not representative of field use Only one simulated cooking task • Hard to do for some stoves Batch-loading stoves: TLUD’s, charcoal

7. WBT Procedure

8. WBT Procedure  45 min. SIMMER  COLD START HOT START Tboil Tboil-6degC Water Temperature Fresh Water Troom Time

9. 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)?

10. WBT – Preparing for the Test Gather Supplies Scale - 6000g range, 1g resolution Temperature sensor – waterproof Fixture for suspending temperature sensor Wood moisture meter or oven for fuel MC

11. WBT – Preparing for the Test Gather Supplies • Timer or watch • Pot – standard or dedicated, no lid • Heat resistant pad for scale • Charcoal scooper/tongs • Char tray • Heat resistant gloves • Water – room temp, • - at least 10 liters • Fuel – air dried, uniform • - 2 bundles ~ 2kg each

12. 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

13. 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

14. 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.

15. WBT – Conducting the Test Phase 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

16. WBT Results Three test phases, real-time measurement (CO2, CO, PM)

17. THE NEW DEAL

18. 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

19. WBT Results Low Power Specific Consumption (MJ/min/L) *IWA Metric

20. WBT Results High Power CO (g/MJd) Low Power CO (g/min/L) *IWA Metrics

21. WBT Results High Power PM (mg/MJd) Low Power PM (mg/min/L) *IWA Metrics

22. WBT Results Indoor Emissions CO (g/min) Indoor Emissions PM (mg/min) *IWA Metrics

23. WBT Results Temperature Corrected Specific Fuel Consumption (g/L) wood mass that was consumed to evaporate the moisture in the wood equivalent mass of wood stored as char Eq. dry wood consumed = dry wood mass – -- Best indicator of fuel consumption

24. WBT Results Average Firepower (W) How big is your stove

25. WBT Results Turndown Ratio

26. 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

27. Aprovecho Emissions Equipment PEMS & LEMS Portable (or Lab) Emissions Measuring System IAP Meter Indoor Air Pollution Meter

28. PEMS • Collection hood collects stove emissions • Sensor box measures: • CO • CO2 • PM (laser) • Flow rate in duct • Temp in duct • Pot temp • Uses: • Measure stove emissions (WBT, CCT) • Stove design tool

29. PEMS PM Sensor: Scattering Photometer

30. Diagram Courtesy Monox PEMS CO Sensor: Electrochemical Cell

31. PEMS CO2 Sensor: NDIR

32. PEMS 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

33. LEMS and Gravimetric

34. LEMS 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). With gravimetric we move to… Categorization studies (e.g. Tier 4)

35. PEMS Laser vs. gravimetric • Photometer • Output = scattering coefficient (1/m) • Physical meaning: fraction of light scattered away for every meter a light beam travels Mass concentration estimated by:

36. 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

37. PEMS Why use gravimetric? • Gravimetric • Particles are collected on a filter and weighed.

38. Indoor Air Pollution Meter PM Sensor: Scattering Photometer(same as PEMS)

39. Diagram Courtesy Monox Indoor Air Pollution Meter CO Sensor: Electrochemical Cell(Also used in PEMS)

40. Indoor Air Pollution Meter Features • Sample speed selection • Fast: Every 10 seconds Battery life: 3 days • Medium: Every 1 minute Battery life: 2 weeks • Slow: Every 10 minutes Battery life: 1 month • LED indicates meter is on • Serial port for live graphing

41. IAP Meter Data Processing Software • Outputs include: • Graph of emissions vs time • Average concentrations • Maximum and minimum concentrations • 15 minute average concentrations

42. 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

43. More Information www.aprovecho.org • Spec sheets • Brochures • Manuals • Data processing spreadsheets

44. Documentation • www.aprovecho.org/lab/pubs/testing Download testing protocols