[elestudent]

Hi guys,

I'm an electronics student and I'm working on a project where I'm using a MQ7 CO gas sensor to mesure car CO gas emission, the output of this sensor is in PPM, I'm updating the measure of the car emission every 4 to 6 seconds, and I'm getting a chart like this (see the chart attach), ok now I want to get from this chart the rate flow (every second) and the whole quantity of emission, I want to get it as precis as possible.

To get the flow, there're two ideas in my mind and they both gives me a diffrent results, either I do the output of the sensor (Y(i)) divided by the time between this value (d(i))and the previous value (d(i-1)) or should I do the value of the output minus the previous value of the output divided by the time between the two value.

so in nutshell :

either I do this : Y(i)/[(d(i)-d(i-1))]

or : [Y(i)-Y(i-1)]/[(d(i)-d(i-1))]

if there're any other physical equation or way to get this I will be very happy to learn!

Thank you so much for your time & sorry for my English.
 

[chenbeier]

I would  calculate  [Y(i)+Y(i-1)]/2*[(d(i)-d(i-1))]. So you get an average.

[Enthalpy]

ppm is dimensionless.
What is the unit of the sought "rate flow"?
What is the unit of the sought "whole quantity of emission"?
My guess is that you need something completely different, involving the complete exhaust throughput. Just dividing by a time doesn't look like the answer.

By the way, are these ppm by volume or by mass?

And since the output of the sensor is not an accumulation, I would not make a difference of the samples.