Attention physics fans...

[ChesterBrew]

So, is it better for the coolant (in this case, water) output to running out of the HX colder or warmer? I have a lot of water pressure so I can run it fast or slow and have the output spit out hot or cold water. I can't really figure out which is more optimal and why?

Optimal heat exchange is making the water hotter and the wort cooler as quickly as possible. As yap says, you're best served getting the wort cooled as quickly as you can once the boil terminates to reduce problems with the end product. This partially depends on volume of the end fermentation volume. This will happen optimally by having the hot material (wort) in controlled contact with the cold material (water) as as to exchange heat from one to the other as quickly as possible. Heat transference can only happen if a hot surface is in contact with a cool surface and they have enough time to make it happen.

You can throttle the water supply to make this happen (at the expense of lengthening the wort cooling process) or throttling the wort supply (at the expense of using up more water in the cooling process.) Personally, I'm still working on a pre-production pilot system and extending the cooling process given the volume doesn't matter. But, for others in a true production environment, the opposite will be true.

[gitchegumee]

Check again to make sure that your water flows in where the wort flows out. Sure sounds like you have it backwards. Other than that, you could take the heat exchanger apart and make sure the plates are in correctly.

[fa50driver]

Your water temp is the likely culprit

any thoughts on how much i might be able to increase flow if i can drop the city water from 74 F down to say 50 F (or less)...?


Pose that question to whomever designed/modified your HX. They should be able to give you an answer fairly easily. There are lots of variables (H2O flow rates, number of plates, etc)

No matter how many plates you have or how much H2O flow, the fact that your input water is 74 decreases the effectiveness of your HX tremendously. My water temps range from low 50's to high 40's depending on the season. The difference in knockout times between those temps is about 20 min. (1bbl/min in winter compared to .5bbl/min in summer).

Alternatively, add a secondary HX using glycol. Bottom line is that your 74 F city water is too warm to be effective without either pre-chilling it or adding a secondary HX with glycol.

[ParishBrewingCo]

Sounds like you have 2 potential issues. Your water out temp should be pretty frickin hot if you are counter-current flow. Your likely issues in my opinion (as a degreed chemical engineer with 10 yrs experience designing and operating all kinds of heat exchangers) are either:

1.) Your heat exchanger is really small and/or you have no heat transfer surface area (plates installed incorrectly and you are only flowing water through a fraction of the heat exchanger before it exits) or

2.) You are flowing the water co-current with the wort. If your outlet water is the same temp or only slightly warmer than the wort outlet, you very well are flowing your water in the wrong direction.

In a properly sized heat exchanger, even with 75F water in, the outlet water should be upwards of 160F when cooling a 210F hot side liquid. Your outlet wort temp should be at least 10 deg higher than your water in temp at decent flow rates so don't expect it to get to 75F at decent knockout speed if your cooling water in is at 75F. You get diminishing returns regarding heat exchange when you get closer to the cooling water inlet temp as the delta T is getting smaller and smaller. Difference in temp is what drives heat exchange.

[yap]

I thought I found the problem...

but I was wrong...

Turns out this HX was set up for a multipass arrangement. A multipass is supposed to be for low flow rates or close approach temps, neither of which is valid in my case. I just pulled the thing apart (again) and removed the turning plates. Hooked it all back up and am re-testing with hot water out of the kettle. Now its worse than it was before...much worse.

Pumping 74 degree water against 200 degree "wort" and I can only get about a half a gallon a minute of "wort" at 100 degrees. that is a greater than 25 degree difference in water in vs wort out temp at almost no flow. the water coming out of the exhaust is still just above room temp. If i increase the outflow to get 2-3 gallons a minute the "wort" comes out at about 120+ degrees.

I realize that dropping the incoming water temp through glycol assist will help, but I feel something else is going on here. I am getting a bigger chiller in order to glycol assist this process but it seems I am so far off right now that I don't know if it will completely fix my issue. I still think I am missing something somewhere. Seems like dropping the water temp 20-30 degrees won't be enough to drop the wort temp 50 degrees or will it?

I ABSOLUTELY POSITIVELY have the flow going counter current. The plates ARE 100% installed correctly. I don't believe the HX is undersized based on my calculations but of course my math has failed me before. It has 50 plates 20" x 5". It originally only had 30 and I added another 20 which did nothing to help...

My water flow rate is up to 6 gallons a minute. I'd settle for 3 gallons a minute wort output, but as i said i can only get about .5 and now that i took the turning plates out i can't get below 100 degrees.

i will be on the phone with the people who rebuilt the unit for me tomorrow to see what they have to say....

thanks again everybody...

[yap]

btw...

based on the overwhelming response that i must be flowing concurrent instead of counter-current, i decided to switch the water in and out. apparently it doesn't make any difference...!!?? no matter which direction i flow the water, the results are the same....

now i'm really confused...

[fa50driver]

Very strange indeed. If you contact the original manufacturer, they will likely have the specs that the HX was built around. (input/output temps and flow rates)

The part that seems the strangest is the outlet H2O temp - with the low flow rates and low outlet H2O temp, it definitely seems like the plates aren't put together correctly.

Even with a correctly sized HX, you will probably still want to pre-chill that 74 degree H2O (or have a secondary glycol HX) in order to knock out within a reasonable time limit. (I think 15 bbl in 30 min's is about as long as I like to wait)

let us know what you come up with...

[yap]

Very strange indeed. If you contact the original manufacturer, they will likely have the specs that the HX was built around. (input/output temps and flow rates)

unfortunately it is a vicarb and they are no longer in business. I am going to make some calls tomorrow and see what kind of advice i can get..


thanks again..

[Scott M]

You might try calling these people as well, C. J. Mulanix Company, Inc. http://www.cjmulanixco.com/Vicarb/index.php

Not an endorsement, just someone I found on the web....

"C. J. Mulanix Company, Inc. is a stocking distributor of Plate Heat Exchanger Gaskets, Plate and Frame Heat Exchangers or for Plates for Plate and Frame Heat Exchangers. We also engineer, thermal rate, expand, clean, and sell plate and frame heat exchangers. We have been stocking and selling plate heat exchanger gaskets and heat exchangers for nearly 15 years."

70 Leddy Street
Buffalo, NY 14210

Phone: (716) 822-5006
Fax: (716) 822-1648

[Natrat]

unfortunately it is a vicarb and they are no longer in business. I am going to make some calls tomorrow and see what kind of advice i can get..


thanks again..

Sure they are. Only now they're called Alfa Laval Vicarb!

I had a similar problem with a vicarb, once. Took it apart a bazillion times trying to figure out why it wouldn't cool.

Turned out on that model (an old one) the gaskets alternated in a weird way. I had to turn every second plate upside down. Take a close look at your gaskets...it was very counter-intuitive...but once fixed, the thing rocked!

I ended up marking all the plates with a file to make sure they went together correctly after that.

Good luck. I hope that helped in some small way...

Nat

[yap]

Sure they are. Only now they're called Alfa Laval Vicarb!

I had a similar problem with a vicarb, once. Took it apart a bazillion times trying to figure out why it wouldn't cool.

Turned out on that model (an old one) the gaskets alternated in a weird way. I had to turn every second plate upside down. Take a close look at your gaskets...it was very counter-intuitive...but once fixed, the thing rocked!

I ended up marking all the plates with a file to make sure they went together correctly after that.

Good luck. I hope that helped in some small way...

Nat

Natrat, would you mind if i sent you a picture of the plates to see if it is similar to your scenario? The plates have a N and S (north and south i assume) marking on opposite ends and it is set up so that they alternate. This seems like the only way it should go together but...

[Natrat]

Send 'er here! I still have pix of the one I rebuilt on one of these old hard drives. Let's see if we can match them up!

Nat

[yap]

heres a link to pics.

http://www.flickr.com/photos/blank_slate_brewing_company/sets/72157630299889550/

the plates are about 20"x5". the plate pics are the multipass turning plates thus the two closed holes. all other plates have 4 holes. i have added 20 plates since these pics were taken so the pack is bigger now.

thanks

[rudge75]

Contact CJ at the address and phone someone gave above. Your plates look nothing like mine that vicarb built in '95 - almost like every second one was reversed.

If your system is set up for a two pass, it might be that both passes are happening at the same time instead of the cold water cooling first, THEN the glycol loop as per standard practice.

I'll try emailing you some photos.

Edit:
Just to clarify: I will endorse CJ's work because he was able to get us new seals and extra plates for a 16 year old vicarb HX that we just rebuilt ourselves. Works wonderfully now, no leaks, holds pressure and new style gaskets he sent were a cinch to put in right. Our old gaskets were held in place with this odd steel BB ball arrangement, the new gaskets just clip in over the edges of the plates after we nipped off all the old BB's on the plates.

[Natrat]

Ok,

those are a mini-version of the plate/gaskets I had to deal with.

I'm not finding my assembly pictures, but I did compare them, and they are the same.

So you need to get 4 plates, and look at them very carefully...you want the flow from the left to through the plate, then up to the top..then through TWO plates, then down to the bottom.

From the right you want the flow to start at the top, go through the first plate, then down...then through TWO plates, then up.

From what I remember, there will be two different plate types...one has the gaskets right side up, the other is "upside down." Well, flipped over. Whatever...I need to find those pix. They will make everything clear! But I would bet dollars to donuts that the problem is with plate orientation, and you're jumping plates and creating airspaces, getting only 20-25% of the cooling you should get.

I'll search the other harddrives for those photos. Sorry for the delay.

Nat