On the physical properties of moist air in air heaters
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An air heater is being designed; using ASPEN EDR for calculations, the pressure of the air is 100 KPA and the relative humidity is 76%. Question 1: Should condensation of moist air be taken into consideration? 2. How should the physical properties of moist air be handled?
Question 1: Should condensation of moist air be taken into consideration? First, calculate it in Aspen+, then import it into EDR – the software will take these issues into account. It seems that there’s no such issue here. 2. How should the physical properties of moist air be handled? The software comes out directly.
Asking the original poster. If moist air condenses, the relative humidity must have reached 100%, and latent heat of vaporization is released. How is moist air with a certain relative humidity represented in ASPEN? Is it by calculating the mass ratio of dry air to water vapor separately? Has the original poster solved this problem?
Simply enter the flow rates of dry air and water respectively
This is how I did it. But there is one problem: how to determine whether the water in moist air is water vapor.
Aspen will do the calculations for you, so there’s no need to worry. You can try using a flash tank; if it’s not saturated, everything will exit through the gas phase
Is that so? Set one type of material with components AIR and H2O; determine the moisture content based on relative humidity, calculate the mass ratio of AIR to H2O. Should the overall vapor fraction be set to 1? It is still better to set up two separate streams of material for AIR and H2O, using the MIX module as well as the flash process you mentioned.
Just add air and water to the stream of material; specify the desired temperature and pressure for the flow. The system will calculate the balance automatically, so there’s no need to include a flash tank – simply connect the flow to the module you need. After the calculation, right-click to view the results for that stream of material; if it’s not saturated, the mass fraction will be 1
Got it, thanks~ By the way, for this issue of heat release in wet air, with a temperature range of around 0 to 30°C, components being AIR and H2O, would it work to use the IDEAL property method along with Henry’s law for the components?
The ideal gas law can be used; there’s no need to define Henry’s law constants, and you also don’t need to know things like the solubility of air in water