# Fumes energy

1. Oct 10, 2011

### fantommass

Hi!

I'm working on problem, where I have to estimate energy, lost due to flue gases, i.e. some amount of natural gases burned in some time period, say [t0;t1].
Burning is used for some material heating. I need to find energy, lost by gases (gases, after combustion), which goes out from flue. Heating is performed linearly, for example from point [0;100] to [2;400] (first coordinate is time in hours and second is temperature), so temperature dependence is like this:
T(t)=150t+100​
I was told that I have to calcule specific enthalpy change in order to calculate energy lost by fumes:
Qf=MΔhf
where M is mass of fumes and Δhf is specific enthalpy change.
Also I know that specific enthalpy depends on temperature throuth relation:
hf(T)=0.28T-4.6​

So, for specified heating schedule, enthalpy depends on temperature through this:
hf(t)=0.28(150t+100)-4.6=42t+23.4​

I'm I write, when I calculate change of specific enthalpy by integrating in time interval function hf(t)?:

Δhf=∫(42t+23.4)dt​