Mixing air how much water leaving?

[peet_dk]

I have a situation like this:

Where C is a air stream from a pipe, and A is the sky. Droplet will be made, and there will be fog.

Now I have to calculate the amount of water leaving the air.

In my book I found this equation:

Q_water = Q_dry.air.C * (x_A - x_C)

But do it have to be point C and A? Why not the two points where RH=100% ?

And how do I know how much water that there will be in the air as fog, and how much will raining down?

 

[Mech_Engineer]

I would recommend looking into a psychrometric chart, and modeling processes on that chart: http://en.wikipedia.org/wiki/Psychrometrics

 

[peet_dk]

Thanks for the reply.

Here is the cooling processes into the diagram, A-B and A-C. If you look at the two processes, will they produce the same amount of condense?

 

[peet_dk]

I made a pdf of the diagram, with more details on it.

 

[alphy]

I would like to clarify a few things about the situation you have described. Firstly, the equation you have mentioned is known as the Dalton's law of partial pressures, which states that the total pressure of a mixture of gases is equal to the sum of the partial pressures of each individual gas. In this case, the equation is being used to calculate the amount of water leaving the air.

Now, in order to accurately calculate the amount of water leaving the air, it is important to consider the specific conditions and variables involved. The equation you have mentioned assumes that the air stream from the pipe is completely dry, which may not be the case in reality. Additionally, the values for xA and xC represent the mole fraction of water in the air at point A and point C, respectively. These values are typically determined experimentally and can vary depending on the specific conditions.

As for your question about why the two points where RH=100% are not being considered, it is important to note that relative humidity (RH) is a measure of the amount of water vapor present in the air relative to the maximum amount of water vapor that can be held at a given temperature. In other words, just because the RH is 100% at a certain point, it does not necessarily mean that all the water vapor will condense into droplets at that point. Other factors such as temperature, pressure, and air flow can also affect the formation of droplets.

To determine how much water will be in the air as fog and how much will be raining down, it is necessary to consider additional variables such as the rate of condensation, the rate of precipitation, and the distribution of water droplets in the air. These factors can vary depending on the specific environmental conditions and may require further experimentation or modeling to accurately determine.

In summary, the equation you have mentioned can provide a general estimate of the amount of water leaving the air, but it is important to carefully consider all the variables and conditions involved in order to accurately calculate this value.