Physics Help Forum Real Life Thermo/Fluids problem: Moisture transfer between two streams?

 Jun 19th 2015, 07:51 AM #1 Junior Member   Join Date: Jun 2015 Posts: 2 Real Life Thermo/Fluids problem: Moisture transfer between two streams? This isn't a university question, but a real life one, and I was hoping to get some help with this problem. There are 2 streams from 2 pipes merging into one:Air @ 60C with 0% RH Wet DSG (10% Water Content) Info: When the two streams merge into one, the volumetric flow rate is 5000m3/h of material and air at 60C and there is 14 kg/h of water vapour. The pipe diameter is 300mm. The streams merge into one (with the above properties) and then travel along an insulated pipe for 25meters. What I would like to calculate is whether the air can suck up all the moisture from the wet DSG and spill out air dry DSG and wet air at the end of 25 meters. I am completely stumped by what I figure to be quite a simple problem. Here are my attempts at solving it: I first tried idealizing the situation, using basic thermo principles such as Q=MC(T2-T1), taking away the fact that the streams were moving and realized that moving streams do contribute a large part. I also tried adiabatic mixing, but that didn't pan out either because this process is non-adiabatic. Any ideas? Thanks
Jun 19th 2015, 08:26 AM   #2
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This is a chemical engineering issue, but considerbly more detail is needed to make any sense of what is happening.

In particular a proper description of the phases present in the mixing tube and what you mean by the exit conditions

 whether the air can suck up all the moisture from the wet DSG and spill out air dry DSG and wet air at the end of 25 meters.
Obviously you cannot expect the air to remove all the mositure.

Are you trying to find the optimum air to particulate? ratio

 Jun 19th 2015, 10:10 AM #3 Senior Member     Join Date: Apr 2008 Location: Bedford, England Posts: 668 It is a little bit unclear what is going on in your post, From the linked document on DSG, I assume the DSG is in powder form. Is the DSG powder cold, with initial water content in the liquid phase, Or is the DSG powder hot, leading to the initial liquid phase to be vapour? If you assume all the water is converted to vapour, and distributed evenly (volumetrically) through the mix, I think that would give you an upper, best possible, boundary limit to the problem. Your actual/real solution must be WORSE than this, but will at least indicate if there is a ballpark in the field... __________________ You have GOT to Laugh !
Jun 19th 2015, 10:22 AM   #4
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 Originally Posted by studiot This is a chemical engineering issue, but considerbly more detail is needed to make any sense of what is happening. In particular a proper description of the phases present in the mixing tube and what you mean by the exit conditions Obviously you cannot expect the air to remove all the mositure. Are you trying to find the optimum air to particulate? ratio
This process can be completely idealized. And what I'm looking for is not a detailed solution, but a very high level step by step of what I should do to solve this problem.

Jun 19th 2015, 10:26 AM   #5
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 Originally Posted by zijincheng This process can be completely idealized. And what I'm looking for is not a detailed solution, but a very high level step by step of what I should do to solve this problem.
You should start by answering the very reasonable questions, without answers to which, it is impossible to make any other worthwhile comment.

MBW has amplified my request for much more detail about the properties of the streams.

 Tags life, moisture, problem, real, streams, thermo or fluids, transfer

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