Making a refrigerated compressed air dryer-crazy thoughts?

[signcrafter]

Having some coffee this morning surfing the web and had a thought pop into my head. I run into a lot of commercial refrigeration equipment so have access to all sorts of stuff and love to tinker with projects and make something out of nothing. I don't have any experience with how refrigerated air dryers work but guessing it's a compressor, condenser, and evaporator/heat exchanger or some sort. Is it a crazy thought to piece together a system to cool and dry the air coming out of my compressor? Not talking about running a copper coil in a fridge like some I have seen. But more of the industrial type of dryers that cost big bucks. From the little bit of googling I did this morning it sounds like these dryers use the cool air coming out of them to pre cool the hot incoming air and then that incoming air goes into a heat exchanger to cool the compressed air to 35-40 degrees. But that's my limited knowledge of things so far until I dig into it more. Anyone familiar with the workings of these air dryers? Is it possible to piece together a system like this? I'm familiar with automotive ACs and have all the stuff to repair them and have my 609. But not familiar with the heat exchanger or evaporator in a system like this would work.

 

[PCustoms]

How much air do you use and what for?

I bet those dryers are big energy user..

 

[Dig Doug]

I’ve seen a lot of these type of set ups

How much air are you needing ?
you’ll need to size the system accordingly

 

[signcrafter]

How much air do you use and what for?

I bet those dryers are big energy user..

I’ve seen a lot of these type of set ups

How much air are you needing ?
you’ll need to size the system accordingly

Right now, not much since compressor isn't hooked up after the move. I don't use a ton of air, use mostly cordless. I do have a tire machine that uses air, looking at smaller sandblaster cabinet that will get used every now and then. Every great once in a while I have a ALC pressure pot sand blaster and paint spray gun. Then the usual blow guns, tire inflators, things like air fluid evacuators and brake bleeders, air hammers and die grinders when need something more then the m12. Nothing too crazy and the stuff that draws a lot of air is only used once in a while. Compressor is a rolair that puts out somewhere around 15CFM.

This isn't something I "need" but more of a thought that popped into my head and if I can put one together as a project with parts I can get for next to nothing it would be a fun project and have nice dry air at the same time. Compressor is shut off probably 95% of the time so not too worried about power consumption, guessing it won't be much more energy then a 2nd fridge since it's using mostly the same parts.

I'm sure one of those aftercooler setups like in the video would be fine for me. But just had the thought that since I run into a lot of refrigeration equipment if it would be possible to make a project that uses that stuff to make an air cooler it might be a fun project to do. If it's not possible or going to cost a bunch of money it's not worth it to me. But like I said I enjoy projects like these.

 

[signcrafter]

Video of what I'm thinking,

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The heat exchanger is the part that makes this project more then just a fridge cooling system. Looks like they use a heat exchanger and flow the air over an evaporator inside a tank. More to it then that but that's the basics. I don't think I'll be able to do something like that and not sure I can find an already made exchanger like this for a decent price. But, if I was able to do something like use a heat exchanger like in the video above mounted in an enclosure next to an evaporator it may be able to cool the air fast enough to achieve results similar.

 

[cvairwerks]

Buddy did a dirt cheap cooler for his shop...50' of 1/2 tubing coiled in a plastic trash can set inside an old fridge. Filled the can with water and plugged it in. Cut two holes in the side of the fridge for inlet and outlet. He vented the tubing at full pressure every once in a while to blow any accumulated condensate out. Replaced it with a commercial dryer unit when he moved to a screw compressor.

 

[RTM]

There have been several threads on this

Choosing refrigerated air dryer for air compressor

These units seem pretty small, and not overly expensive, and a lot less hassle than building copper pipes, radiators etc. My air compressor is 80 gallon 2 target, 17 cmf at 90 psi. I'm looking at these 2 dryers, but can't seem to figure out any difference...

www.garagejournal.com

Refrigerated air dryer question

I just picked up an Eaton 52-dry air drier for a couple hundred dollars. It appears in good condition, I’ve not gotten it plumbed yet but my question is there are two valves ******* sticking out of the side with what I think is a very bad English translation that says “ Pollutant outlet. Daily...

www.garagejournal.com

 

[engineer2]

I used to build them during breaks from college. My dad designed them.
IMHO, best to find a nice used one. SCFM can be bigger than your compressor, but too big is a waste of electricity.
Small ones like 5 SCFM often use 1/4 " tubing for connections.
Real old ones used R12 or R22. Newer ones use 134a
Best to get one with a 35F dewpoint or so. Some only go to a 50F dewpoint.

Basically (as you have figured out):
Moist air goes into the air-to-air heat exchanger.
Then it goes to the refrigerant-to-air heat exchanger where it is chilled, water is condensed out and drained. The water drain trap has a serviceable bowl with a float valve.
The treated cold air goes through the air-to-air heat exchanger to re-warm it. This increases thermal efficiency.

Basically 2 refrigeration types, cycling and non-cycling.
Cycling: the refrigeration system turns on and off depending on demand.
Non-Cycling: the refrigeration system runs continuously. Used in plants where there is constant use of compressed air.

The expensive part of building one will be the 2 heat exchangers. You can build tube-in-tube heat exchangers using copper pipe, but it won't be any cheaper than store-bought heat exchangers. Internally finned copper pipe works well for building your own.

Another method is using a desiccant air dryer. You can get very low dew points with this type, but they have to run all the time because of the desiccant drying cycles for the two desiccant beds. One dries the other. They are suitable for 24/7 factories.

 

[Damon L.]

I just did the oil cooler aftercooler on my setup. I remote mounted the cooler above my compressor room, and will have a box fan start when the compressor runs. I haven't got the wiring done yet on the fan, but I can hold the tube going into the tank with my bare hand when it is running.

Another method is using a desiccant air dryer. You can get very low dew points with this type, but they have to run all the time because of the desiccant drying cycles for the two desiccant beds. One dries the other. They are suitable for 24/7 factories.

I also have a pair of dessicant dryers salvaged from my employer when we did a compressor swap and new dryers came in the package.. I have not yet plumbed them in, as I wanted to see how dry I can get with just the aftercooler. Based on your statement, is it even worth plumbing them in if my air system sees limited use?

I do blast and do body work, so sanders, paint guns, etc. are happening, so I may use more air than half of the board or so.

 

[Shoreline_]

Did you start making anything yet? I work with compressed air dryers everyday. The best kind to design for your application is a thermal mass type. I got one for free from a customer. The ***** is heeeaaaavvvvyyyy filled with glycol.

 

[Shoreline_]

I just did the oil cooler aftercooler on my setup. I remote mounted the cooler above my compressor room, and will have a box fan start when the compressor runs. I haven't got the wiring done yet on the fan, but I can hold the tube going into the tank with my bare hand when it is running.



I also have a pair of dessicant dryers salvaged from my employer when we did a compressor swap and new dryers came in the package.. I have not yet plumbed them in, as I wanted to see how dry I can get with just the aftercooler. Based on your statement, is it even worth plumbing them in if my air system sees limited use?

I do blast and do body work, so sanders, paint guns, etc. are happening, so I may use more air than half of the board or so.

Desiccant dryers are super inefficient and we only sell them in places they need air dryer than freezing. Ie a compressor room sends air outside to another building in the winter. The dewpoint of 35f on a refer dryer won't get the water out and the pipe outside at 15f will condense the water out of the air even more and it'll freeze. To put it in perspective we have a customer with (2) 75hp screws. In the summer with a refer dryer they can run 1 screw at 60% capacity. In the winter both 75s have to run when the dessi dryer is running.

 

[MacMcMacmac]

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