ANALYSIS OF THE EFFECT OF FOUR PARAMETERS ON A CHARCOAL STOVE

• André NDECKY PhD Student• Centre d’Etudes et de Recherches sur le

Energies renouvelables (C.E.R.E.R) • Université Cheikh Université de Dakar (UCAD)• Email:cerer@ucad.sn• Site: http://cerer.ucad.sn

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CONTENT• Introduction• How to minimize the effort while studying the influence of

several parameters on stove performance?• Diagram of effect of four parameters at two levels • The experimental design and results• Interpretation of results of total efficient by ANOVA• The optimal levels of total efficiency • Factors or combination of factors that will maximize total

efficiency• Interpretating results of CO emission at the boil by ANOVA• The optimal levels of CO in boiling• Factors or combination of factors that will minimize CO

emission• Conclusion ETHOS 2014

INTODUCTION

This presentation is about a short experience in the stove testinglab of CERER. The objective was to test a Statistical method(experimental design) that reduces significantly the number ofnecessary tests while evaluating the influence of severalparameters on the performance and emissions of a stove.We selected four parameters of interest during the test of a

charcoal stove prototype with secondary air. Those parameters are:

• the secondary air• the type of fuel• the quality of the initial fuel batch• wind, simulated by a fan ETHOS 2014

THE STOVE WITH POT AND FUEL

Carlotta Werner’s photos ETHOS 2014

COMBUSTION CHAMBER OF STOVE WITH THE HOLES FOR SECONDARY AIR

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FUEL USED (BALLS OF TYPHA AND CHARCOAL)

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How to minimize the effort while studying the influence of several parameters on stove

perfomance?We used the WBT for measuring the performance and emissions(CO,CO2, PM) of a prototype “Éclair” stove at as statisticalmethodology a Design Of Experimental (DOE) that is generallyused when you want to:• Maximize the number of independent variables to be

analysed• Minimize the variance of the error • Control certain variables at specific levels. The analysis of variance (ANOVA) is the basic statistical tool used

for this DOE, to understand the effect of several factors. Other tools such as comparative test of Newman Keuls can be used in addition the analysis of variance

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DIAGRAM OF EFFECT OF FOUR PARAMETERS AT TWO LEVELS

1. PERFORMANCE2. EMISSIONS (CO,

CO2, PM)

STOVE (A)

Without secondary air (-1)

With secondary air (+1)

FUEL TYPE (B)

Charcoal (+1)

Typha carbonised (-1)

QUANTITY OF FUEL ©

Filled under holes Ty(730g) Ch(500g)

(-1)

Filled onboard Ty(1000) Ch(730)

(+1)

FAN (D)

Without ventilation (-1)

With ventilation (+1) ETHOS 2014

EQUATION REPRESENTING THE MODEL

Yijklm = U + Ai + Bj + ABij + Ck + ACik + BCjk + ABCijk + Dl + ADil + BDjl + ABDijl + CDkl + ACDikl + BCDjkl + ABCDijkl + ɛm(ijkl)

Yijklm: Response (Efficiency or CO emissions)U: General average of tests.Ai: Effect of treatment of AAbij: Effect of treatment of combinaison ABɛm(ijkl): Error due at random

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THE EXPERIMENTAL DESIGN AND RESULTSETHOS 2014

EXAMPLE OF CALCULATION

Source of variation

Degrees of freedom (Df)

Sum of Squares (SS)

Mean of Square (MS)

Fexp Fthe

Treatment(A)

ErrorTotals

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INTERPETATING RESULTS OF TOTAL EFFICIENCY BY ANOVA

SOURCE DF ALIAS SS MS Fexp Fth

A (Stove) 1 BCD 0,00124 0,00124 4,06 4,54

B (Fuel type) 1 ACD 0,00572 0,00572 18,72 4,54

C (Quantity of fuel)

1 ABD 0,00498 0,00498 16,30 4,54

D (Fan) 1 ABC 0,00005 0,00005 0,15 4,54

AB 1 CD 0,00148 0,00148 4,83 4,54

AC 1 BD 0,00098 0,00098 3,20 4,54

AD 1 BC 0,00075 0,00075 2,45 4,54

ABCD 1 (1) 0,00000 0,00000 0,00 4,54

ERROR 15 0,00458 0,00031

TOTAL 23 0,01977

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HOW TO FIND ALIAS?Alias with I = ABCD

A*ABCD =(A2B1C1D1)mod2 = BCA

B*ABCD = A1B2C1D1)mod2 = ACD

C*ABCD = A1B1C2D1)mod2= ABD

D*ABCD = (A1B1C1D2)mod2 = ABC

AB*ABCD = (A2B2C1D1)mod2 = CD

AC*ABCD = (A2B1C2D1)mod2 = BD

AD*ABCD = (A2B1C1D2)mod2 = BC

(1)*ABCD= (A1B1C1D1)mod2 = ABCD

To say that a factor and a combination of factors are aliases, if it is equal with the mode of his product with the total.Example: : AxABCD = A2BCD so the mod (A2BCD) = BCDThen A is alias of BCD, which means they have the same significant effect in the expected response

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THE OPTIMAL LEVELS OF TOTAL EFFICIENCY Combination of factors (AB) Average

WITHOUT SECONDARY AIR-BALLS OF TYPHA

24,4%

WITHOUT SECONDARY AIR-CHARCOAL 25,9%

WITH SECONDARY AIR-BALLS OF TYPHA 24,2%

WITH SECONDARY AIR-CHARCOAL 28,9%

Combination of factors (CD) Average

UNDER THE HOLES-NO VENTILATION 27,9%

UNDER THE HOLES-WITH VENTILATION 26,6%

FILLED ONBOARD-NO VENTILATION 23,5%

FILLED ONBOARD-WITH VENTILATION 25,3%ETHOS 2014

FACTORS OR COMBINATIONS OF FACTORS THAT WILL MAXIMIZE TOTAL EFFICIENCY

STOVE With secondary air

FUEL TYPE Charcoal

QUANTITY OF FUEL Under holes

FAN With Without ventilation

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INTERPETATING RESULTS OF CO EMISSION AT THE BOIL BY ANOVA

SOURCE DF ALIAS SS MS Fexp Fth

A (Stove) 1 BCD 3273,4 3273,4 0,85 4,54

B (Fuel type)

1 ACD 1183,2 1183,2 0,31 4,54

C (Quantity of fuel)

1 ABD 104917,9 104917,9 27,32 4,54

D (Fan) 1 ABC 19175,5 19175,5 4,99 4,54

AB 1 CD 4072,9 4072,9 1,06 4,54

AC 1 BD 142,4 142,4 0,04 4,54

AD 1 BC 13731,5 13731,5 3,58 4,54

ABCD 1 (1) 0,0 0,0 0,0 4,54

ERROR 15 57594,6 57594,6

TOTAL 23 204091,5 ETHOS 2014

THE OPTIMAL LEVELS OF CO IN BOILINGUnder the holes 156,04

Filled onboard 288,27

Without ventilation 250,42

With ventilation 193,89

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FACTORS OR COMBINATIONS OF FACTORS THAT WILL MINIMIZE CO EMISSION

STOVE Without Secondary air

With secondary air

FUEL TYPE Typha Charcoal

QUANTITY OF FUEL

Under holes

FAN With ventilation

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CONCLUSION

The objective is achieved as only 24 tests were enough to study the effect of four parameters simultaneously. The best combinations were found to maximize performance and minimize emissions.

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THANK YOU FOR YOUR KIND ATTENTION

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