Placing compressor above evap

[STEvil]

Been working my way through stickies and threads and came across mention of "floodlock" due to refrigerant entering the compressor.. http://www.xtremesystems.org/forums/showthread.php?p=374786#post374786

Would putting a sort of "sump chamber" between the compressor and evap (along the suction line) or placing the compressor above the evap to keep liquid from reaching it be something worth looking into?


Also i'm assuming 9 feet of 0.031" cap tube for the R507 compressor im going to be using should put me at about 215w or so of heat load handling capability?

[pythagoras]

Yes its called an accumulator ;)

Regards

John.

[STEvil]

Darn, thought I was onto something.. lol ;)

any disadvantage of overshooting heatload?

Say tuning for ~250w but only having 160w heatload?

[pythagoras]

Thats where the accumulator would come into effect. Less load means less refrigerant vapourised and so more heading its way to wards the compressor.

250 watts seems way to high a load to tune for, for a single evap system. I believe astek aimed for that, or close to it with the original LS and then they retuned for version 2.

Regards

John.

[STEvil]

anyone tried putting a valve near the evap so you can restrict flow mimicking longer cap tube for lower heat loads?

EDIT

How about multiple cap tubes? Different lengths for different heat loads and use on/off valves near compressor all attached in parallel.

[pythagoras]

Yes, its called a txv :) Two for two tonight Stevil :D

Regards

John.

[Stewie007]

When liquid refrigerant gets into your compressor it causes it to surge. Its pretty hard to get that to happen in these. It should be enough to draw your suction line upwards, and then down into the suction line.

[STEvil]

yay? ;)

running out of questions to ask lol..

EDIT


It should be enough to draw your suction line upwards, and then down into the suction line.

?

[pythagoras]

But you are asking all the right questions! Havnt you noticed that you are actually designing your system here ;)

Regards

John.

[Stewie007]

You can also make an auxilliary evaporator on the outside with a fan blowing over it.. doesn't have to be anything special. It'll just make sure the vapor... is all vapor... Kind of a jury rig though :p

[STEvil]

But you are asking all the right questions! Havnt you noticed that you are actually designing your system here ;)

Regards

John.

Yeah, its been floating in my head a month or so... :p:

EDIT

Stewie - I believe thats the idea of the accumulator.. has anyone considered building the accumulator onto an area to cause subcooling?

[pythagoras]

Hehehehe,

three for three, its called a suction line HX, you wouldnt be taking the Urine now by any chance would you ;)

Regards

John.

[Stewie007]

I know, but I was just saying that you could fashion something, instead of spending money on an accumulator. One thing that I would spend money on though is a back-flow stop valve. When your system shuts down, alot of times liquid can back flow in your compressor. So you place it on the discharge line to prevent that from happening.

@Pythagoras... I don't follow you with the urine thing :p:

[STEvil]

Urine?????

Yeah, i'd build it unless I could pick it up dirt cheap.

[pythagoras]

Ygpm :d

[STEvil]

crazy brits :P

[EMC2]

*hands the Pythy one a cup* :p:

@Stevil... it's a drier :D Oh, wait, never mind... you haven't asked yet :lol:

Some people also wrap the suction line around the bottom of the compressor to insure no liquid is left in the line and as a side benefit to help cool the compressor.

[kayl]

stevil thats a good idiea.
if ya want oit at the bottom and not want to use accumulator just do a dip or a coil so liquid refrigerant has a place to rest and hold for a sec when compressor starts.
capillary line sound about spot on too.

[STEvil]

Putting all the info into a text file, lots of it is usefull in a sticky ;)

[STEvil]

ok, time for another question:

If I used a Chilly1 evap and put the cap tube into the spiral chamber from the top about 1/2" then drilled out the center and attached the suction to the top of that (leaving the walls ~3-5mm thick or so) with 2-4 holes at the base of the center into the spiral chamber, how would this affect performance.

Am also considering chemically etching entire inner surface or roughing it up good with a dremel.. and tapping the center with tap&die set to create turbulence, surface area, etc etc etc....

Thoughts, suggestions, ideas?

EDIT

Here is an image of what I mean.. not sure which direction of refrigerant flow would be optimal really though...

http://www.wcroller.com/los/linkpics/head.jpg

[STEvil]

Bump.

How about "oversized" evaps?

[LostInSpace278]

I think for one you would lose a lot of capacity trying it this way. It's easier for the vapor to rise than it is trying to push it to the bottom. Remember as it goes down/up it is absorbing heat. There for it is at it's coldest near the cap tube. Trying to force the vapor down, IMO is not a real good idea. Drilling out the center is what will cause you to lose capacity. I think maybe the acid etch theory may be a good one though.

[LostInSpace278]

Over sized evaps, as in wide or tall?

[STEvil]

It's easier for the vapor to rise than it is trying to push it to the bottom.
It goes where pressure is the lowest, there are two directions of flow possible in this case (up the spirals, or down).


Over sized evaps, as in wide or tall?
Given the thermal conductivity of copper, either?