[Open Source Design Project] - Falling Film Evaporator



This is great, I’m working on a model of the exergy heat exchangers for TD simulation, can you make the part file available to add to the model? I realize it’s likely just a first iteration, but we can easily swap it out later when changes are made. Also, I must agree that ASME vessels are the right choice to start, but they become unnecessary if you use peristaltic or dosing pumps to facilitate continuous throughput.


Here are some cutaways of distribution solutions. Your design is similar the the second one here, but adding the bowl above the distribution tubelets ensures fluid is introduced around the edges and floods the plate evenly.


Yeah, I considered using a trough-drain system above the plate/tubes for that reason. I have a busy day but when I get back to the computer I’ll attach the .iam assembly.


Know anybody capable of welding something like this? @PinnacleStainless can you?


@indofab and I can do the fab/welding, we have tig welders, rotery tables, and stuff for electropolishing the welds. Add some Numbers to that drawing you have and we can make the part.


Yeah !!! Lol


So you guys could build a shell and tube where the tubes extrend past the plate on one end?


I can see the welding on that getting tricky fast…but with short enough extensions is shouldn’t be impossible.

my TIG is pretty rudimentary, so I could be way off :wink:


Agile said no, as did several shops in the Portland area. Having raised tubes and flooding the side would be the easiest way to evenly fill


I have a qpump milton roy that tops out at 28L/h but it is two slow so i need either a couple or a higher out put metering pump.


The feed solution is projected onto the evaporator in streams vs. a spray and that has helped with it being pulled over. I run the hot side around 170f and and it seems to run down the walls pretty well.


My pops has a couple patents on laser welded steel beams…pretty sure he has a steady relationship with both small shop and commercial type companies that can do it. Won’t be cheap though! Haha

Why can’t the tubes be inserted into holes and welded? Someone talk me through the welding of the tubesheets please, because I’m clearly missing something. The bottom side is flush, just like any other tube/shell heat exchanger.

@HempBaker interesting. I’d like to see that thing run. I can’t say I would personally do it like that - but if it works, it works…


Because of the physical dimensions of the torch, getting the arc in to the joint becomes harder as you go. Or you have to space the tubes further apart.

Not having spent hundreds of hr swinging a tig torch, my grasp on the issue may be flawed


Right, I understand that much, but then how are welded tube/shell heat exchangers typically done?

The alternative would be a gasketed instead of welded exchanger. They’re nice because you can take apart and clean easily, though tube/shell is usually CIP anyways. Maybe someone can offer an opinion on that. I’ve got some gasketed ones being fabricated right now, so we’ll see how they do…praying for no cross contamination of fluids.


Going in a tight circle at the end of a tube, over and over, works. Beyond a certain length extension, you just can’t get the angle on the dangle.

Gasketing makes more sense than the press or thread in extensions I was going to suggest…


yeah, no problems! shoot me or @Indofab the drawing.


That’s where the gas lens and purge welding come in. Elecrtrodes can be bent at angles to get in there further.


I’d probably just cut the holes to the proper size to press fit the tubes with a little shoulder to rest on the plate when fully seated into the plate. Welding it would be damn near impossible. You could also have it milled from a thicker chunk of metal.


Starts getting questionable when steam is factored in


That was where I was at with it with agile, was planning on having @Lilibel make me a bunch of little PTFE inserts to stick in the tubes