Calculation of the temperature of mixed gases
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I would like to ask fellow sailors: when two gases at different temperatures are mixed together, how should the temperature of the resulting mixture be calculated? Which physical property parameters are related to it?
It is necessary to determine whether the heat effect of mixing these two gases is endothermic or exothermic; the enthalpy of the gas after mixing equals the sum of the enthalpies of the two gases before mixing, plus the heat effect.
Reply to 2# ilikec5426: Thank you for your answer. If the two gases do not react when mixed, does that mean there is no heat effect?
Reply to 2# ilikec5426: I’d like a specific example – what is the temperature when saturated steam at 200 degrees and natural gas at 300 degrees are mixed together under a pressure of 15 kilograms? At the same pressure of 15 kilograms, what is the temperature when superheated steam at 260 degrees is mixed with natural gas at 300 degrees? Thank you!
This calculation also requires the values of the two fluids
Reply to 3# perfectf: The two gases do not react with each other, but there is still a thermal effect; just like in solutions, mixing them results in a thermal effect. It’s the same principle as when NaOH is added to water – a thermal effect occurs in that case as well. However, there is an exception: if these two gases are ideal gases, then the heat effect is 0.
Reply to 4# perfectf: This can be calculated using the Aspen simulation software – it’s quick. If you try to do it manually, it’s very tedious! !
So, is the temperature after mixing of hot and cold fluids also calculated by setting the sum of the enthalpies before mixing equal to the enthalpy after mixing? For example, consider two streams of water with temperatures ranging from 0 to 100°C, whose flow rates and temperatures are respectively m1/T1 and m2/T2. Then the temperature of the mixed fluid is T = (m1T1 + m2T2) / (m1 + m2), right?