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Bash1803
19-03-2014, 09:14 AM
Good Morning Gentlemen,

I apologise that something like this may have been posted before, but I am approaching the limit of my experience and could really use some help on this one.

I have a Li Br absorption chiller which has suffered a fractured evaporator bundle. What is strange to me is that the tubes have fractured from the inside with longitudal fractures along the tubes and also more than one out of the 400 or so have gone at the same time; potentially indicating a shock pressure in the evaporator?

So in summary, there are three things that you absorption experts could help me with.....

1) Does anyone have a pdf or any other detailed literature on the absorption cycle, components etc. aside from the very basic stuff in normal RAC text books

2) Specifically any detail on purge pumps i.e. why are they used, what happens if they don't work etc.

3) Any detail on crystallisation i.e. what is it? why does it happen? how do you prevent it?

Any information would be most appreciated, but I am now intrigued as well as stumped, so the devil in the detail so to speak is what I am after.

Kind Regards & Thanks in advance,

Bash

HVACRsaurus
19-03-2014, 09:53 AM
This help? Not many of them beasties about anymore.

http://cgproducts.johnsoncontrols.com/YorkDoc/155.16-EG1.pdf

http://www.gasairconditioning.org/gas_cooling_to_publish/pdfs/how_it_works/155.16-TD1%20-%20How%20it%20works%20-%20Single%20effect.pdf

Bash1803
19-03-2014, 01:21 PM
This help? Not many of them beasties about anymore.

http://cgproducts.johnsoncontrols.com/YorkDoc/155.16-EG1.pdf

http://www.gasairconditioning.org/gas_cooling_to_publish/pdfs/how_it_works/155.16-TD1%20-%20How%20it%20works%20-%20Single%20effect.pdf

Thanks for your reply. Kind of similar to the stuff I have been looking at so far, was more looking into the theory behind my points in the more general sense.

But all information is good information.

I appreciate your time, thanks buddy :-)

marc5180
20-03-2014, 08:36 PM
Hi Bash,


It sounds like you have experienced 'frozen burst'. Caused by volume expansion in the evaporator.
There are a few things that can cause this such as
1) Sticking foreign materials in the water side if the evaporator.
2) Chilled water temperature dropping to low
3) Air in the chilled water side
4) Chilled water contamination which causes a scale on the inside of the pipe work.
5) low load.

To answer your questions ;
The purge pump is used for removing air or non condensed gas out of the chiller. Absorption solution reacts on the internal surface of the main body producing Air or hydrogen gas this reduces performance and does the chiller harm.

Do you have a log of the temperatures on the cooling water and chilled water before the fault happened to check if they have suffered with low/high temps? Also has the flow rates been checked and verified to be correct?

Crystallisation basically means that the absorption solution changes from the liquid state to the solid state and causes a restriction in the flow. Normally in the heat exchanger.

Again there's several things that can cause it
It's caused by the high density or high temperature of the absorption solution.
If the cooling water is too low or too high or low flow
Bad purge (high internal pressure)
If the absorption solution is not circulated properly I.e damper closed too much.

Bash1803
24-03-2014, 01:50 PM
Hi Bash,


It sounds like you have experienced 'frozen burst'. Caused by volume expansion in the evaporator.
There are a few things that can cause this such as
1) Sticking foreign materials in the water side if the evaporator.
2) Chilled water temperature dropping to low
3) Air in the chilled water side
4) Chilled water contamination which causes a scale on the inside of the pipe work.
5) low load.

To answer your questions ;
The purge pump is used for removing air or non condensed gas out of the chiller. Absorption solution reacts on the internal surface of the main body producing Air or hydrogen gas this reduces performance and does the chiller harm.

Do you have a log of the temperatures on the cooling water and chilled water before the fault happened to check if they have suffered with low/high temps? Also has the flow rates been checked and verified to be correct?

Crystallisation basically means that the absorption solution changes from the liquid state to the solid state and causes a restriction in the flow. Normally in the heat exchanger.

Again there's several things that can cause it
It's caused by the high density or high temperature of the absorption solution.
If the cooling water is too low or too high or low flow
Bad purge (high internal pressure)
If the absorption solution is not circulated properly I.e damper closed too much.

Marc, thank you very much for your reply, that is fantastic. I haven't had the chance to go back to the site to review, but I will be soon and I'll let you know the outcome.

For the mean time, I have some of the fractured and good tubes from the evaporator, and I'm going to have a little play to see if I can recreate the same longitudinal fractures; hopefully will give me a better idea of the fault condition....

frozenwonderlan
28-06-2014, 03:12 PM
11595
this is picture waht we did for a hot water fired absorption chiller, but your condition I CAN confirm that your absorption chiller chilled water switch not function, it cause frozen chilled water, so it broken the tube,
2)purage pump is used for keep the chiller inside vacuum was enough for evaporatfor cooling, but the oil need special for absorption chiller.
3)for crystallisation,it has many situation, 1st is the generator temperature is too high,2st it has too much air inside the chiller, it means the vacuum no good, 3st the cooling water temperature is too low,