[gafoorcp]

hiii.....
In AVL we are getting the emission parameters as mass fractions only....can anybody suggest me the procedures to convert this mass fraction into g/kg of fuel or g/kWh units.....
thanking you
gafoor

[mfarhad03]

Calculate the total number of moles in the exhaust gas from the volume flow rate(m3/hr) of exhaust gas using the ideal gas law PV=nRT.

Number of moles in the exhaust gas flow, n =RT/PV, where R (R = 8.3145 J/mol·K) isideal gas constant, V is exhaust flow rate in m3/hr, P is pressure in N/m2 and T istemperature in K.

2. Multiply by the ppm value (y*10-6, assume y is measured ppm of gas) for eachspecies of pollutant to get the moles per hour of that species

3. For each pollutant species, multiple by the molar mass (molecular weight) to getgrams per hour. Divide by power output in kW to get grams per kiloWatt-hour

I have also attached a calculation file for your understanding.

[gafoorcp]

thanks a lot for your valuable information.....

regards
gafoor

[mfarhad03]

Hi gafoor
Do you help me about AVL Fire Spray and Combustion program?

Best regards
farhad

[gafoorcp]

hii...
i am also very new in AVL and also in CFD.
though i will try my level best to help you..
feel free to ask me about your problems and we will discuss....
my mail ID is gafoorcp@yahoo.com

regards
gafoor

[muhammet]

Hi all,

i am using AVL fire but i am doubtful about the results of emissions. i did some simulation and tuned the cylinder pressure with exp. but the emissions did not tuned.

i use extended zeldovich model for NO

and one more; when i use the other model for NO, it gives different resuls at same temperature curve.

could any one help me?

thanks.

[muhammet]

i thing you can get total mass curve (or data) and then if you multiply the total mass with mass frac. you will get the mass of i species( for ex. NO ). then you must find the value of mass per hour ( with using the engine speed ). then devide it with power.

TM = total mass* injector hole number (because it gives total mass results for only per hole)
NO mass = NO mass frac.*TM

NO [g/kWh] = {(NO mass)*(n/2)*60} / power

! engine speed must devided by 2 if it 4 strokes
! 60 is represent the minutes in hour.

[rajeev50588]

Originally Posted by muhammet

i thing you can get total mass curve (or data) and then if you multiply the total mass with mass frac. you will get the mass of i species( for ex. NO ). then you must find the value of mass per hour ( with using the engine speed ). then devide it with power.

TM = total mass* injector hole number (because it gives total mass results for only per hole)
NO mass = NO mass frac.*TM

NO [g/kWh] = {(NO mass)*(n/2)*60} / power

! engine speed must devided by 2 if it 4 strokes
! 60 is represent the minutes in hour.

Paste the following code in a notepad and change the file extension from *.txt to *.frml
(frml is the extension which works as a formula file for AVL FIRE)

Upload this formula and you will get the NOx values in ppm directly

// --- NOx_ppm.frml ---
// Must be used with cell-selection only!
// Computes the average NOx concentration in [ppm] according
// to the specified assumed molar mass of NOx as fl2 result;
// molar mass of NOx in g/mol
#define REAL_assumed_molar_mass_of_NOx 38.0

$$init
double ppm_nox = 0.0;
if(!init){
if(divisor > 0.0) ppm_nox = sum / divisor * 1.0e6;
if(IAMPRO < 2){
print "NOx_ppm.frml: avg NOx concentration in", name, ":", ppm_nox, "[ppm]";
}
sum = ppm_nox;
divisor = 1.0;
}
$$formula
divisor += ap * vol / (8314.4 * temp);
return YNOXMF[index] * den * vol / REAL_assumed_molar_mass_of_NOx;



Once you get the NOx ppm values from above formula use the following:

NOx (gm/hr) = 0.001587 * NOx (ppm) * Exhaust Flow (kg/hr)
and NOx (gm/kWhr) = NOx (gm/hr) / Power (kW)

Since ESE diesel calculates BSFC (gm/kWhr) , Power (kW) and AFR, you can get following

a) Fuel Flow = BSFC (gm/kWhr) * Power (kW) = Fuel Flow (kg/hr)
b) Air Flow (kg/hr) = AFR * Fuel Flow
c) Exhaust Flow (kg/hr) = Air Flow + Fuel Flow

Please note all the above calcluations do not contain the NOx correction factor which is dependant on humidity, ambient temperature etc which of course cannot be determined by AVL FIRE.
Usually the NOx correction factor is 0.94 to 0.95 which will be further multiplied to the above NOx (gm/kWhr) value giving the final answer

This is taken from ISO 8178 emission calculation standard
In this standard the engine power has weightage factors which I have not considered here.. (for simplicity )

[amin_u50]

I used this formula but it does not work. could you please send me the .h file?
amin_u50@yahoo.com