1. The document describes a scratch test conducted to measure bio-tar and carbon-soot (BTCS) deposits on cooking utensils when used on a MAGH CM series wood combustion stove. 2. The test involved using matchsticks to scratch radial lines on the bottom of an aluminum vessel after burning 1kg of wood fuel. The weight gain of the matchsticks provided the BTCS deposit measurement. 3. The results showed an average BTCS deposit of 1.78 mg per matchstick, corresponding to a total deposit of 782.88 mg per kg of wood fuel burned.

1. Scratch Test: To establish Bio-Tar and Carbon-Soot (BTCS) deposit on cooking utensils when used on wood combustion stoves of MAGH CM series.<br />Aim of the Test: To establish bio-tar and carbon-soot (BTCS) deposit, (weight basis) on cooking utensils.

2. Requirements of the Test:Stove under test: MAGH CM Series-1<br />Burner Size, diameter:<br />Fuel Wood Material:<br />Fuel Wood Size, Diameter:<br /> Length:<br /> Weight:<br /> Moisture Content:<br />Material of the Vessel: Aluminum<br />Vessel Size: Diameter (at base): 140 mm <br /> Height:<br /> Weight of Water in the Vessel: 5 kg<br />Ambient Air Temperature: 37oC<br />Bulk Water Temperature in the Vessel, initial, at intervals of 1 minute, till 1 kg fuel is burnt to ash:<br />Size of Scratch-Test Match-Sticks: cross section 2 mm x 2 mm, length 35 mm<br />Number of Scratch-Test Match-Sticks (of cross section 2 mm x 2 mm, length 35 mm): 8 when the number of vessel supports on the stove are 4, 6 when the number of vessel supports on the stove are 3.<br />Weight of each Match-Stick before scratching: 14 mg<br />Weight of each Match-Stick after scratching: 15.6 mg<br />Net Average Weight of deposit per Specimen-Match-Stick: 1.6 mg<br />Instant when the scratch test is performed and scratched specimens are collected: on complete combustion of fuel (fuel converted to ash)

3. Test Procedure:

4. Weigh the match-sticks before scratch test individually.

5. When the 1 kg fuel is completely burnt, remove the vessel from the stove, drain the hot water and put the vessel in the bottom-up position.

6. Using Scratch-Test Match-Sticks, scratch 8 radial lines starting from the center of the bottom to the periphery of a circle of diameter equal to burner diameter located on the bottom surface of the vessel, if the number of vessel supports on the stove is 4 or if there are no vessel supports. For each radial line scratch, use new match-stick removing tar-carbon soot along with the match-stick.

7. Weigh the match-sticks after the scratch, each individually. Find the net weight of tar-carbon deposit from 8 specimens. Compute the average, wt.

8. Estimate the total Bio-Tar-Carbon-Soot deposit, using: BTCS = Wtotal =[(2πd)/t] wt mg/kg fuel burnt

9. Precautions:

10. All Tests must be done on vessels of same composition (Al), same size (diameter and Height), containing a standard bulk weight 5 kg of water, water having same initial bulk temperatures, same ambient temperatures; same material, size and weight of the fuel, and finally the same diameters of the burners for various stoves under test.

11. While scratching, enough finger pressure must be put on the match-stick to extract both carbon soot and oily tar.

12. Scratch the vessel when hot to get good results. Ensure that the scratched material is deposited to the match-stick, else collect the loose scratched material carefully without any loss of material for weighing purposes. Note: The Scratch-Test Match-Sticks have to be cut to 35 mm length removing the ignition-paste part.<br /> 5. Table of Observations:<br />Stove under test: MAGH CMC<br />Burner Size, diameter: 140 mm<br />Fuel Wood Material: Custard Apple Wood<br />Fuel Wood Size, Diameter: ¾ inches<br /> Length: 3 inches<br /> Weight: 1 kg<br /> Moisture Content: 15% (dry)<br />Material of the Vessel: Aluminum<br />Vessel Size: Diameter (at base): 9.5 inches <br /> Height: 5 inches<br /> Weight of Water in the Vessel: 5 kg<br />Ambient Air Temperature: 37 oC<br />Initial Bulk Water Temperature: 33 oC<br /> Table1. Time-Temperature history<br />Time in minutesTemperature, oCRemarks133.2233.9335.2436.9537.8639.2740.7841.8943.01044.41145.11246.31347.21447.91548.21649.51749.71850.21950.92051.82152.82253.92354.52455.22556.82657.62758.72859.82960.83061.23161.63262.03362.33462.53562.93664.23765.53866.23967.14068.04168.24268.14368.34468.54568.74669.24769.84870.0<br />Table2. Scratch Test data<br />Diameter of the burner, d = 140 mm; Thickness of the Scratch-Test Match-Stick: t = 2 mm<br />Specimen No.Initial Weight , wiBefore scratch, mgFinal Weight, wfAfter scratch, mgNet Weight, w = wi - wfmg11415.61.621617.81.831415.61.641618.02.051615.61.661416.22.271617.61.681819.81.8<br /> Average Weight, wt = w/8 = 1.78mg<br />Estimate the total Bio-Tar Carbon-Soot deposit, using: BTCS = Wtotal =[(2πd)/t] wt mg/kg fuel burnt = 782.88 mg/kg fuel burnt<br />Table3. Bio-Tar Carbon-Soot deposit per Unit Energy abstracted by the Vessel<br />S. No Test Stove ID BTCSmg/kgEnergy Abstracted by the Vessel, kJ BTCS/Energy Abstracted, mg/kg/kJ1MAGH CMC782.88823.080.9523<br />Energy abstracted by the Vessel = Energy abstracted by water + Energy abstracted by Vessel<br /> = (5kg)(sp.heat of water)(70-32) + (0.75)(sp.heat of vessel)(70-32)<br /> = (5 kg x 4.2 kJ/kg K x 38 K) + (0.75 x 0.88 kJ/kg K x 38 K) <br /> = 798 +25.08 = 823.08 kJ <br />V. Ashwini Kumar<br />Email: ashkum_veera@yahoo.co.uk<br />16 March 2010<br />