1. ETHOS Conference, 2014
Performance Evaluation of Biomass Cookstoves: Bureau of Indian Standard (BIS) Vs. WBT 4.2.2
Rajendra Prasad * Ratnesh Tiwari, Amit Ranjan Verma, Risha Mal, V.K. Vijay
Centre for Rural Development and Technology
Indian Institute of Technology Delhi(India)
* Corresponding author: Cell: ,
January 24-26, 2014

2. BIS Protocol
BIS basically the cold start high power phase of WBT 4.2.2
Fuel size for domestic stoves about 3 cm x 3 cm and 4 cm x 4cm for community stoves , length equal to about half the diameter of the combustion chamber of the stove
Moisture content of fuel 5 (±1) %
Each test-1 hour duration
Fuel burning rate- determined before testing
Test setup similar to EPA-5G method with some modifications to meet the requirements of Indian situation
Test Fuel fed in 10 equal batches during one hour duration of testing
Calorific value of fuel determined with the help of digital bomb calorimeter

3. BIS Protocol
Hood–
Duct Velocity-
Surface Temperature(body, handle) not more than 60°C
Opening adjusted so that no smoke escapes from front
Width 1.0 meter, Height 2.34 meter from the base of the hood where stove placed for testing
Hood to collect all the emissions from the stoves
Appropriate duct velocity fixed as per the size of cook stove and burning rate to maintain the required ratio of dilution air less than 150 kg per kg of fuel consumed
The speed is controlled by a frequency variable drive (VFD)

4. BIS Protocol Thermal Efficiency- Emissions- CO ,CO2 & O2 Measurement-
TPM Measurement
Protocols- mainly cold and hot start high power phase of WBT 4.2.2
The size of the vessel and the quantity of water to be taken based upon the burning rate of the Cook-stove
Temperature of water in pot placed on cook-stove to reach around 95°C and then replaced by a fresh pot of water at room temperature
Lid placed on the pot
Non destructive infra red (NDIR) technique for CO&CO2
Magneto-pneumatic analysis method for O2
Gravimetric method using Glass micro fibre filter,GF/A 47 mm dia
Advanced true Iso-kinetic stack sampler based on USEPA methodologies (EPA Method 17)

5. BIS Standards

6. WBT 4.2.2 Protocol Consists of three phases-
◦ Cold-start high-power phase
◦ Hot-start high-power phase
◦ Simmer phase

7. WBT 4.2.2 Protocol Fuel between 1.5 cm x 1.5 cm to 3 cm x 3 cm
One bundles of fuel of 5 kg for each phase of WBT
Pot capacity 7 litre, 5 litre water for each phase of the WBT,
Pot capacity 3.5-liter, 2.5 liters water for each phase
Tests all stoves with similar vessel size and with similar amount of water leaving the burning rate to the operator of the stove to decide based on experience
Lid-not placed on the pot
Local Boiling Temperature- For a given altitude h (in meters), the boiling point(Tb) of water is:
Tb= (100- h/300) °C

8. IWA Performance Tiers

9. BIS VS WBT 4.2.2
BIS- Cold and hot start high power phase in a continuous manner, no break in between.
-No simmer phase – simmer phase in WBT largely works on the residual heat(charcoal left) in the stove. A good design of stove should not leave much of charcoal in the stove after main (high power) phase of cooking.
-Does not subtract the heat value left in Charcoal from the heat value of the total fuel consumed in calculating the thermal efficiency
Emissions measurement in BIS similar to WBT 4.2.2

10. BIS VS WBT 4.2.2 Hood opening is not defined in WBT 4.2.2, BIS does.
EPA 5G recommends “Adjust the distance between the top of the wood heater stack exhaust and the dilution tunnel hood so that the dilution tunnel induced draft is less than 1.25 Pa (0.005 in. H2O)”
Maximum velocity allowable on the face of hood V2 
1.25 = ½ χ 1.2 V22 or 
V2= 1.44 m/s 

11. BIS VS WBT 4.2.2
EPA 5G recommends – “Adjust the damper or similar device on the blower inlet until the velocity indicated by the pitot is approximately 220 m/min (720 ft/min)”- this means a velocity of about 4 m/s
– “In order to ensure measurable particulate mass catch, it is recommended that the ratio of the average mass flow rate in the dilution tunnel to the average fuel burn rate be less than 150:1”
-Steel duct, 0.15 m (0.5 ft) in diameter shall be used for the sampling section
At 4 m/s, in a duct of 0.15 m, flow would be about 254 m3/hr. For 1 kg of fuel burnt in 1 hour, which is the case with several stoves, there is a contradiction between velocity and dilution rate. WBT has not resolved it, BIS has done it by adjusting the velocity depending upon the burning rate of the stove

12. BIS VS WBT 4.2.2
BIS measures the total particulate matter(TPM) while WBT measures only PM2.5 which is a component of TPM.
BIS, before testing a stove and to determine the size of the vessel as well as the amount of water to be taken for testing, the burning rate of the stove is determined. WBT does not do it, tests all stoves with the same vessel and with the same amount of water leaving the burning rate to the operator of the stove to decide based on his experience
BIS, fuel moisture kept at 5(±1)%. WBT uses fuel with 15-20% moisture
BIS- lid is used on pot, WBT no lid on pot

13. The setup at IIT Delhi

14. Experimental Results
Efficiency-

15. Experimental Results
Emissions- CO & PM

16. References
EPA(5 G Method),Determination of particulate matter emissions from wood heaters (dilution tunnel sampling location),pp Sep 16, 1997,
Bureau of Indian Standards, New Delhi, India, on Portable Solid Biomass Cookstove(Chulha)-First Revision, IS 13152(Part-1):1991,ICS ,
Water Boiling Test Version 4.2.2, version-of-the-water-boiling-test-released-at-ethos-conference.html (2013)

17. Thank You