Continue to Site

Eng-Tips is the largest engineering community on the Internet

Intelligent Work Forums for Engineering Professionals

Register Log in
  • Congratulations waross on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Mounting of Additional Heat exchanger

Status
Not open for further replies.
FoolFreshOuttaSchool

FoolFreshOuttaSchool

Mechanical
Jul 8, 2009
6
Hey fellas,

I'm new on the job and my first assignment is to finish up a half completed project. The guy I replaced ordered a heat exchanger to install on an existing cooling system in order increase cooling capacity. Now I have to figure out how he planned on installing it. See pictures below to get better idea of what I'm talking about. My thought was to bolt the new heat exchanger directly onto the existing unit but there will be no room to get nuts and bolts positioned. Any help would be appreciated.

10fxszr.jpg

21cib2e.jpg
 
Replies continue below

Recommended for you

Sort by date Sort by votes
Well, I think that somehow you are going to have to find out what the guy had in mind. The cooler manufacturer may be able to give you the design conditions so that you know what the flow arrangements are for both air and water(?). Get that wrong and your new cooler won't do you any good.

Regards,

Mike
 
Upvote 0 Downvote
You may use a table on a table scheme to get akin support to the new heat exchanger. You may use new attached (even if at some distance) columns to the existent ones, then produce the table outfit above. The columns seem fairly sized and able to stand such scheme. A supplementary stub of column acting as bracket may tie old and new colums, with maybe some rigidization; this might be bolted.

Some lateral extension of the thing will appear in this case and maybe some risk of injury to uncaring workers knocking the bracket.
 
Upvote 0 Downvote
As SnTMan said, who need to know from the heat exchanger designer and/or manufacturer where it should go.
If there is no new fan then the 2 HE's may need some ducting joining them.
 
Upvote 0 Downvote
OK, I understand that to maintain the flow arrangements of air over the new heat exchanger, ducts will be required to direct flow up and through the new unit. ishvaaag, Can you elaborate on the table on table scheme you speak of? I am looking for specifics on how to tie into the existing structure.
 
Upvote 0 Downvote
FoolFreshOuttaSchool, are you SURE these are in series on the air side?
 
Upvote 0 Downvote
No, honestly I'm not. I need to perform a heat balance to determine if stacking these two is the right decision, otherwise like you said, the second heat exchanger could end up a huge paper weight. Obviously the air reaching the second heat exchanger will be at a greater temperature than ambient, lowering said HE's ability to do its job. Any tips on what direction I should take with my calculations?
 
Upvote 0 Downvote
He didn't mean to outright replace the existing bundle, did he? Possibly due to the existing united fouled, tubes plugged due to corrosion, hail storm ruined the fins, .....?

(maybe this is why the fellow is no longer there ;)
 
Upvote 0 Downvote
I've made an attempt to get a hold of him with no luck. I will continue trying. I don't even want to begin bad mouthing this guy... Thanks for the help guys
 
Upvote 0 Downvote
FoolFreshOuttaSchool, if the rating information is available for the new cooler, you should be able to confirm the inlet air temp. If it is above ambient (the exit air temp of the existing cooler), you could feel pretty confident the air sides are in series. You could similarily check the tubeside tmeperatures to see if the tubesides are in parallel or series.

I am kind of assuming here that the units are cooling the tubside fluid. If not, the same concepts would apply.

AllHandlesTaken has a good point, maybe it is a replacement bundle, I am not sure how you would confirm this. You might end up doing a heat balance anyway.

Regards,

Mike
 
Upvote 0 Downvote
Start with Step 1: Understand the problem.

What is the problem with the existing system?
 
Upvote 0 Downvote
The existing unit cools the sewer discharge water coming from various systems of a power plant. Initially, the cooler was adequate, but over time, modifications to the plant have caused an increase in discharge water this cooler sees, in turn, causing the discharge temp to increase to levels that are close to the maximum allowed by the utilities company. The second cooler is intended to increase the rate at which the discharge water can be cooled, thus avoiding potential fines associated with exceeding the max discharge temp. Let me know if this needs further clarification.
 
Upvote 0 Downvote
The concept is easy to understand by thinking on one bigger structural table over the existent. To gain clearance on the projections of the equipment you may need to separate somewaht the legs of the upper table from those of the existing one, hence an interface may be needed betwen them. Since you have H legs, you may use a scheme

H H H

where the left H is the existing leg, the middle H is a sutb between legs, and the right H is the leg of the new bigger table above. By this arrangement you may have the legs of the bigger table upwards from the soil, if structurally correct. If not, simply use a table in table scheme like inpackaging sets of tables of different size, that is what above but with the legs of the bigger table directly supported at ground level.

Respect air temperature you may gain some advantage including a deflector above the entry to the now owershadowed heat exchange unit. This can also be supported by the legs of your new table.
 
Upvote 0 Downvote
Well, there are only so many ways to hook this stuff up.

Water side either in series or parallel.

Air side either in series or parallel.

Since it seems no new fans were ordered, I'll have to guess that your predecessor intended to install the new coil on top of the old coil - placing the air side in series.

As you have already noted, that gives high air-entering temperature to the new coil.

Also, with the two coils in series the airflow will go way down. This seems like a significant oversight.

No way to guess what he might have had in mind for the water side.

I also find myself wondering why one of the water lines to the existing coil is insulted.

 
Upvote 0 Downvote
MintJulep,

You're correct, the air side will have to be placed in series, my boss is not giving me the option to build a new structure to mount the second HE. Any yes, the airflow will go way down, which is a significant oversight but I have no choice. As far as water side, will I gain anything more by running in parallel as opposed to series? The person originally in charge of this project intended to pipe the water side in series. Flow in the top HE and out the bottom HE. I'm questioning his educated guess.
 
Upvote 0 Downvote
Series on the water side will give you the highest delta-T between water and air in both coils.

It makes the best of a poor situation.
 
Upvote 0 Downvote
the new bundle might have bigger/more tubes and as stated the tubes in the old bundle might have had some plugged due to a leak or all the fins are flat/plugged
 
Upvote 0 Downvote
Status
Not open for further replies.

Similar threads

mrmalcolm
  • Locked
  • Question
Effect of post-weld heat treatment on mechanical properties
Replies
9
Views
462
mfgenggear
mfgenggear
Laishetti
  • Question
Feedability of MIG wire 2
Replies
6
Views
983
IFRs
IFRs
mte12
  • Solved
What type of weld is this 9
Replies
14
Views
4K
kingnero
kingnero
P
  • Question
Welding a member on top of an existing weld
Replies
7
Views
4K
pinaki_stahlbau
P
mechengineer
  • Locked
  • Question
Strength weld joint between SA-266Gr2 of TS and SA-312TP316L of tubes
Replies
1
Views
181
EdStainless
EdStainless

Part and Inventory Search

Sponsor

Back
Top Bottom