Paging Engineers - Good Now!

[sn4cktimes]

Anybody know any good reading/video material on trying to understand Lithium Bromide Chiller Units. I'm studying it for my Millwright ticket and this one is working over my brain.

I'd like to think I'm not too dumb... but this one might be above my pay grade a bit.

[Snuze]

I'll throw myself under the bus here... I'm an engineer, I even spent 3 years designing HVAC systems (ducting/airflow side), and I even rebuilt the AC system in my Volvo, and I still don't really understand this stuff.

So unfortunately I don't think I can be of much help short of suggesting Googling and looking on YouTube.

Now if you want to talk vinrations ans acoustics, lets go!

[Snakesm13]

@sn4cktimes Not an engineer by any means but I program controls for stuff similar to this all the time. Mostly off P&ID drawings though.

What specifically are you trying to understand?

[Exage03040]

What do you need to know?

I think this picture explains it better (more simple). Are you familiar with refrigeration cycle?

https://thermaxcooling.wordpress.com/2015/09/03/how-do-absorption-chillers-work/comment-page-1/

[sn4cktimes]

@snakesm13 I think just the multiple things going on at the same time is a bit much for me to grasp is all. There's just a lot of stuff being moved around, and I'm having trouble understanding the "sections" so to speak.

[sn4cktimes]

@exage03040 That is a more simplified drawing. I understand the basic refrigeration cycle. And even things like a chilled water circuit for a building's AC is within my grasp. I think one of the biggest issues I have with this cycle is which vapour is going where, condensing where, and doing what vs what the liquid is doing. Seems to be a few too many simultaneous loops.

[TheBarber]

@sn4cktimes This

has a nice series with good animations.

[sn4cktimes]

@thebarber I've been hitting that channel HARD over the last couple of days. Sadly in that particular video he clips along pretty quickly.

I feel like I'll get it. I'm just trying not to waste time. For all I know this could be a huge component of my exam, or like 2 questions.

[TheBarber]

@sn4cktimes I get that feeling. For some things I can stare at a diagram and figure it out and sometimes for the life of me I just can't figure out the relationships. It helps me to look at a theory of operation and make a map stage by stage on how something works and then I'm able to look back at the big picture and be like "ok, I think I can understand it now" lol. Sometimes it just helps spelling it out on your own terms if you will.

That's my fear of going into any trade. Taking an entrance exam for apprenticeship under the gun.

[Exage03040]

@sn4cktimes said in Paging Engineers:

@exage03040 That is a more simplified drawing. I understand the basic refrigeration cycle. And even things like a chilled water circuit for a building's AC is within my grasp. I think one of the biggest issues I have with this cycle is which vapour is going where, condensing where, and doing what vs what the liquid is doing. Seems to be a few too many simultaneous loops.

It would be like 1000X easier to explain if they had pressures and temps for each drum.

From what I gather.

Basically they're using (green) water as the refrigerant via vacuum (boiling point 3.7C for example). It goes from the condenser as a liquid and evaporates in the vacuum drum. The state change from liquid to vapour is what draws the heat from the lighter blue chilled water. LiBr (red is mixture with water) is the absorbent to quickly transfer the water as condensation collected under vacuum with help from cooling water.

The LiBr and water (red) pumped to a drum and is heated to release the water (back to green in the condenser) and make the LiBr (brown) a concentrate reabsorb the water.

Your drawing is more technical with the control elements shown but I get what's going on.
The only significant difference in the loop is your drawing has a refrigeration pump to catch condensate and pump it back to the spray bar to vaporize, increasing efficiency

[sn4cktimes]

@thebarber The trades are pretty forgiving for the first year, most focus on safety so all the apprentices aren't killed on the job... I'm in 3rd year of 4 and the learning required with this trade is pretty steep. I could challenge the lower level power engineer tickets after my 4th year course and likely pass.

Most trades in Canada start with you getting a job, vs getting the education first. There are pre-employment courses, but they're less common, and usually available if there's a huge amount of people in that trade required. Example, I did pre-employment for my welding ticket in 2007 (I think, maybe started earlier, I can't recall) as Welders were desperately needed in Alberta for the oil/gas sector. Dime a dozen now.

[Snakesm13]

@sn4cktimes said in Paging Engineers:

@snakesm13 I think just the multiple things going on at the same time is a bit much for me to grasp is all. There's just a lot of stuff being moved around, and I'm having trouble understanding the "sections" so to speak.

Got ya, well I’m on my phone and it looks like you are getting great responses. Once I get in front of a computer tomorrow I’ll catch up on this discussion but hopefully you’ll have your answer by then!

[TheBarber]

@sn4cktimes I wish apprenticeships were more popular in the States. Im planning on working with my new service manager on partnering with our local community college and their auto-tech program to get more bodies in the shop.

I think a lot of kids don't realize that you can make damn good money in the skilled trades and it doesn't require going to college for 4+ years right off the bat.

Just don't get comfortable and get stuck like I am lol.

[sn4cktimes]

@exage03040 The vacuum part helps a bit to understand why things are moving about as they are. I'm assuming the "cooling" water is going to like a cooling tower, the "chilled" water is the "product" here, and the driving heat source is from like steam or something like that.

I think the concentration part might be a big key I'm not getting. Or maybe I just did... the bromide solution stays concentrated as water vapour is ejected from the hot bromide and moseys over to the condenser. Thereby explaining how it can absorb the water in the vacuum portion....

It does seem needlessly complex though, pumping to towers to release the heat you just added to drive the cycle to cool another loop.

[sn4cktimes]

@thebarber Well, that's why I'm working on a second ticket that is pretty multi-disciplinary. It is the jack of all trades ticket. Gotta know pretty much something of everything, until it's what you're working on, then you need to know everything about it. Some guys stay pretty general, some get pretty specialized. My current job is pretty random. Sometimes I'm fixing overhead doors, sometimes I'm machining a new coolant spider nozzle, sometimes I'm repairing electrical, pneumatic, hydraulic, mechanical thingamabobs.

[ClassicDatsunDebate]

@sn4cktimes here’s a good basic explanation of the condenser/evap cycle...

It answered your question about how the generator seprates the LiBr from the water.
I work on specific parts of the large Trane chillers, the circulation pumps mostly so I only know enough of the actual cycle to be dangerous.
Fun fact, the generator pump and the condensate pump are actually one pump with two impellers driven on the same shaft. It’s a weird design but kinda cool.

[Exage03040]

@sn4cktimes said in Paging Engineers:

@exage03040 The vacuum part helps a bit to understand why things are moving about as they are. I'm assuming the "cooling" water is going to like a cooling tower, the "chilled" water is the "product" here, and the driving heat source is from like steam or something like that.

I think the concentration part might be a big key I'm not getting. Or maybe I just did... the bromide solution stays concentrated as water vapour is ejected from the hot bromide and moseys over to the condenser. Thereby explaining how it can absorb the water in the vacuum portion....

It does seem needlessly complex though, pumping to towers to release the heat you just added to drive the cycle to cool another loop.

Yeah, so the cooling water is just cooling water to condense the vapours.

The chiller water is the low temperature brine circuit water and is what you actually use for your localized Air Conditioning or Refrigeration systems.

I did a quick colour shop to correspond with that simplified drawing... Maybe it helps?

[TheBarber]

@sn4cktimes Sometimes it's just fulfilling enough to know a bit about everything. Other times it's nice to be a master at something. I wish my job allowed specialization but we are trained to be masters at nothing really.

[TheBarber]

@classicdatsundebate said in Paging Engineers:

Fun fact, the generator pump and the condensate pump are actually one pump with two impellers driven on the same shaft. It’s a weird design but kinda cool.

Yes, turbos are very cool.

[ClassicDatsunDebate]

@thebarber actually it is designed similar to a turbo now that you mention it. Only, both impellers are driven by a 60 HP electric motor.

[sn4cktimes]

@classicdatsundebate Besides the overly repetitive narrator, that was by far the best so far. I get it much better now. That was terribly oversimplified, but I think I needed that level to work on the more complex bits.

[sn4cktimes]

@exage03040 That helps immensely! Thank-you!

[frinesi2]

It appears to run on some form of electricity.

[Exage03040]

@sn4cktimes said in Paging Engineers:

That helps immensely! Thank-you!

Okay good. I can keep my marine engineering license for another 3 years. Back to goofing off.

[sn4cktimes]

I was feeling pretty worried about this unit, but on a second pass through the material, about 80% now seems quite simple. And not rote data memorization, like some units seemed to be. I usually do best on the math/blueprint/comprehension parts of tests anyway. The blah blah blah which size/number/pitch/etc type questions is usually where I'm a little weaker. Which I'm also personally fine with, that's what charts are for, to save my brain space for better things.

Thanks a bunch everyone who chimed in. That was very helpful on the thing I understood the least for my upcoming test.!