Dehumidifer Size?

[aenigma]

BrianH:
Yeah frost on the compressor is a definate sign of liquid slugging.Just frost on the suction line near the compressor can indicate liquid slugging.
You could use a heater wrapped around it to boil off the remaining liquid.

[BrianH]

Thanks Brians256 and aenigma


I will keep an eye on the frost after I get everything assembled and working with water/anti-freeze and heat load. Are there specially designed heater wraps just for this or what should I look for?

Never thought about cool loss thru a system. I do plan to insulate very well. I have a ~1/2 HP compressor which should be good for 1200BTU's. Should be eqough to cool anything I throw at it. This is my first attempt at extreme cooling!

[bikr]

dehumidifier + pump + some tubing + inline with toilet = solved problem of emptying.. --Josh

[BrianH]

dehumidifier + pump + some tubing + inline with toilet = solved problem of emptying.. --Josh

??huh?? .... I don't understand .....

Did you flush anti freeze down the sewer .... What about out planet??

[bikr]

flush the water the dehumidifer catches --Josh

[bikr]

i'm stupid , i obviousley didn't read the entire thread.. sorry.. I was under the impression you were actually using it as a dehumidifier to reduce condensation .. my bad.. --Josh

[BrianH]

!!!!!!!!!!!

I didn't know whether to flame or explain!

[aenigma]

BrianH:
Well I am not sure exactly where to get a heater, you could find one at a hardware store but they seems spendy(about 23 bucks is the cheapest I saw).

[Brians256]

You aren't going to get something much cheaper than that $23 unless you go dumpster diving and strip out heating elements from junk.

The more that I think of it, though, I'm convinced that a better solution is to use a TXV in series with a capillary tube. The problem with TXV's is that they don't have the ability to finely control high constrictions. But, restrictions can be summed. So, if you add a restriction after the TXV, you should be able to have the best of both worlds.

I can think of another (really interesting!) way to do it, but, it would require some really hefty microcontroller work. Basically, you could PWM the TXV valve based upon superheat feedback. This way, you could overcome the inability of the TXV valve to fine-tune it's constriction. Basically, you could do the same thing that fuel injectors do in a car. Squirt a little bit every time slice, and regulate the time period based upon the load. I wonder if the idea is patentable! It's better for our purposes than using a variable speed DC motor on the compressor (which the refrigeration companies are moving towards for energy savings).

[aenigma]

Well I don't think he want's to do any real heavy work to it, just basic stuff.If he did want to do some real work, he could just change some things and get -40f easy using.
Just use some spiraled copper pipe for the evaporator(for ease of use and making it a little more compact) and just charge it for a lower load.

[BrianH]

Absolutely correct aenigma

I do not have the knowledge or the tools to do those kind of mod's.

I can bend pipes, fill the container, insulate, etc


Now if you need mainframe programming done.....

[Brians256]

Simple is good! I just like to daydream about what someone COULD do. If I had the time, I'd be doing it myself!

[BrianH]

Here is another problem with using a dehumidifier ... the evapourator in my is aluminum (I am pretty sure). My blocks are copper. Will corrosion be a problem with these setup?

If so, how do we prevent it or slow it down? Will the anti-freeze help a lot? If so, what type of anti-freeze should we use? What water to anti-freeze ratio should we be aiming for? May the aluminum coils can be coated with something to prevent corrosion?

[Brians256]

There *might* be corrosion where they meet, but refrigerant is not like water. So, you wouldn't get charge carriers that help galvanic corrosion. You have to have water (or something else that can complete an electric circuit with dissolved ions being moved from one point to another) in the system between the dissimilar metals to get galvanic corrosion.

If you do it right, there won't be any water inside the refrigerant loop at all.

If you have copper and aluminum both in water, then you have to worry about galvanic corrosion.

[aenigma]

Yeah that is what he is talking about, submerging his aluminum evaporator in a res while using copper blocks.
One sure fire way to stop that is painting the evaporator.

You could make a heat exchanger, tie strap some copper pipe directly to the aluminum evaporator(I am assuming it is flat aluminum pipe wound up) and then insulate it.

[BrianH]

aenigma has it correct, the evaporator coil will be submergered in water.

Any idea what I could paint is with? Would a plastic based paint or spray work? Will it be damaging to the coils?

[Brians256]

Just use some methanol or antifreeze. If you are going cold, you might need the frost protection anyway.

As for damaging the evaporator, I don't think so. Paints are very inert. The only drawback is that they form a thin insulation layer.

[BrianH]

I think I may have found some really good stuff to prevent corrosion. It's Valvoline Zerex ExtremeLife 5/150 . It's product testing indicates VERY little corrosion will occur as shown here .

So far, this looks to be the best bet for corrosion protects.

[Pug]

Just to add...
My dehumidifier had aluminium vanes on the evaporator but the pipes were copper.
I ended up removing all the vanes (as they are designed for channeling air anyway, not fluid) leaving just the copper element to be submerged.

[jhurliman]

Originally Posted by BrianH

Here is another problem with using a dehumidifier ... the evapourator in my is aluminum (I am pretty sure). My blocks are copper. Will corrosion be a problem with these setup?

If so, how do we prevent it or slow it down? Will the anti-freeze help a lot? If so, what type of anti-freeze should we use? What water to anti-freeze ratio should we be aiming for? May the aluminum coils can be coated with something to prevent corrosion?

In the HVAC industry we use brass dielectric unions between dissimilar metals. But for galvanic corrosion to exist, two dissimilar metals must be in contact with a flow from the anodic to the cathodic metal. Since there is vinyl tubing separating the radiator from the block, that's not an issue but you do have to deal with the evaporator coil itself, which is copper piping wrapped with aluminum fins. I'm looking in to anti-galvanic additives for coolant, will post later.

[jhurliman]

Originally Posted by Pug

Just to add...
My dehumidifier had aluminium vanes on the evaporator but the pipes were copper.
I ended up removing all the vanes (as they are designed for channeling air anyway, not fluid) leaving just the copper element to be submerged.

Be careful, generally when the copper piping is extruded through the aluminum fins a layer of aluminum is left on the copper piping. On my evaporator coil all the pipes are covered with an aluminum layer. It's not hard to tell the two metals apart so just make sure that you're using only copper.