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Crane paper, exchanger
5

Crane paper, exchanger

Crane paper, exchanger

(OP)
Hi, Where can I find the Crane Technical paper Nº 410?
Thanks

RE: Crane paper, exchanger

See that google seach box near the top of this page?

Type "crane technical paper 410" in that box.  Click the Web radio button and click on "search".

RE: Crane paper, exchanger

(OP)
Yes, I know serach in google, but if I do it, I find many websites where the Crane paper is used by reference but I need to know what "say" the paper about K factor for exchanger calculation.

Thanks.

RE: Crane paper, exchanger

(OP)
You're rigth IRstuff (TTFN). I don't want to pay for.

Thanks.

RE: Crane paper, exchanger

Well, you've probably burned a couple of hours of engineering time already.  At $20/hr, your investment is already more than the cost of the paper.

TTFN



RE: Crane paper, exchanger

I don't think it is in there.  I just looked in my copy, and did not see any chapter on "K factor for exchanger calculation".

RE: Crane paper, exchanger

I second Monkeydogs comment.  It will not help you design an exchanger.   Look in Kern.


Regards
StoneCold

RE: Crane paper, exchanger

Lblopez

Are you really trying to ask "When I'm calculating the pressure drop in a line, what K-value do I use for a heat exchanger?"

If so, the answer is "This is not found in Crane Technical Paper 410, which looks at flow through valves, fittings, and pipe.  You would obtain the pressure drop across the heat exchanger from the manuafacturer's data sheet or by doing a separate calculation for pressure drop."

By the way, I recommend spending the money for the Crane manual.  It comes in either English or metric units, is reasonably cheap, and is well worth it!  Some companies will even pick up the tab for it.

Patricia Lougheed

Please see FAQ731-376 for tips on how to make the best use of the Eng-Tips Forums.

RE: Crane paper, exchanger

Lblopez,

FYI, there are some useful heat exchanger affinity laws in the GPSA Engineering Data Book under the heat exchanger tab. If you have a spec sheet (or field data) for one set of flow conditions (mass flow, density, viscosity, thermal conductivity, etc), the heat transfer performance and pressure drop can be estimated for other conditions. Relations are given for both the shell and tube side. Some geometry changes (baffle spacing, tube diameter, etc) are accomidated as well. There is even a worked out example. Obviously some judgement on applicability is required (for example if new conditions involve a phase change), but these are still very useful quick calculations.

About all Crane 410 will be useful for relative to exchanger work is as a reference for basic formulas- i.e. once the pressure drop is known at a given flow rate and density, Crane will show you how K can be calculated from your data. Of course due to the nature of heat exchangers, K may not neccessarily be a constant for other operating conditions.

best wishes and good luck,
sshep

RE: Crane paper, exchanger

Patricia, good to see you back!!!

RE: Crane paper, exchanger

Welcome back, Patricia!

TTFN



RE: Crane paper, exchanger

(OP)
Ok, I didn't explain good

I'm doing a cooling water system evaluation, becouse there have some troubles. We  doing a Visual flow simulation, in the exchanger window, the pakage need a K value wich is assosiated with pressure drop. I dont know how I can calculate this K for make a better simulation. This K factor produce a change in the pressure drop by each change in the flow.
I can do a simulation without use this K but this would be erroneous, becouse I think, that some troubles that have the plant in study, is that the pipeline have a big pressure drop and the water in not come in to the exchanger in High vacuum distillation and Delayed Coker unit.

The Visual Flow's manual say that this K factor equation is reported in the Crane Technical paper 410.

Thanks everybody.

P.D.: Here US$ 35 is a considerable amount of money and I can't buy it.

RE: Crane paper, exchanger

Lblopez

I understand your difficulty.  However, having in hand my Crane manual, I still don't have enough information to provide you an answer.  There are different formulae and values of K, dependent upon the component.  For example, a full bore gate valve has a K of 8fT where fT is the friction factor.  However a tapered bore gate valve has an entirely different K, depending on the amount of the taper.

The pressure drop across a heat exchangers (which is how I am interpreting "exchanger" in your posts) is not discussed in Crane.  It has values for straight lengths of pipe, both gradual and sudden changes in pipes, and for various types of fittings and valves.

If you are wanting the K value for piping leading up to a heat exchanger (and not across the heat exchanger itself) then you need to get the K value for each length of pipe, each change in pipe diameter, each elbow, tee, valve, etc.  This is a considerable amount of work.  

I realize that US$ 35 might be a lot of money; however, I question what was spent on the Visual Flow software and how important the results are.  If you are wanting more accuracy than just ignoring the K factor completely, then you need to have some basis for the values used.  At least try and convince your management that this information is necessary to run the program.

Patricia Lougheed

Please see FAQ731-376 for tips on how to make the best use of the Eng-Tips Forums.

RE: Crane paper, exchanger

Lblopez,

Hey, you, with the "asno barato" company!

If you would describe this heat exchanger in detail, and describe the fluid and flow through the side of the heat exchanger you want pressure drop estimates for, we MIGHT be able to help you!

What kind of heat exchanger is it?
Shell and tube?  Plate and frame?  Other?
Are you interested in the pressure drop in tube side or the shell side?
Is it 1 pass, 2 pass, 4 pass?
Describe the baffles?  20% cut?  25% cut?
Baffle pitch?
How many tubes per pass?
What size O.D. tubes?  Wall thickness?  I.D.?
Tube length?
What's the fluid?  Water?
What's the flow rate?
Inlet T?
Outlet T?
Etc., etc., etc.?

Good luck,
Latexman

RE: Crane paper, exchanger

I think I speak for most people here when i say that this site does not endorse distrubtion of illegal copies of software or books e.g.

However i think that many publishing companies have special prices for 3. world countries and sometime the opertunity to buy issues printed with slightly lower quality at significantly reduced prices. This will however require that you investigate this locally.

Best regards

Morten

RE: Crane paper, exchanger

MortenA,
Interesting ethics question.  If the Lblopez were to ask for someone to post or e-mail a page of the Crane paper, that would be illegal (easy ethic answer).  But if he asks for the K factor for a particular fitting, I don't think that is illegal or unethical.  
It is not clear what Lblopez needs yet.
If your collegue across town called on the phone, and asked for the K factor, wouldn't you give it to him?  Or would you tell him to go buy his own paper?

RE: Crane paper, exchanger

Lblopez

K = ft*L/D, where ft is the fully turbulent flow friction factor, L is the equivalent length of pipe and D is the pipe diameter (in L units.)  If you can approximate the equivalent length and the friction factor and if you know the pipe diameter, you can approximate the K value.

It seems you are looking for an overall K value for the heat exchanger.  Perhaps the Wolverine Engineering Data Book II might help, it gives a compressive look at heat exchanger calculations, including pressure drop calculations.  
http://www.wlv.com/products/databook/databook.pdf

MortenA,

You raise a good point regarding the distribution of illegal copies of software or books, but I think copyright law (in the US) allows for information shearing within reason:

Quote (Encarta):

A very important exception to the rule of copyright infringement is the concept known as fair use. Under this principle, the law permits the use of portions of copyrighted works for such purposes as criticism, comment, teaching, and research, even without permission of the copyright owner. In deciding whether a use is a fair use, courts consider such factors as the purpose of the use, the nature of the work, the amount of the work taken, and the effect it will have on the value of the original work. Some examples of fair use include quoting excerpts from a book in a review, scholarly article, or term paper; copying and distributing a newspaper article to illustrate an educational lesson; and using portions of a work in a parody of that work, such as a spoof version of a song. The Supreme Court of the United States has held that it is also fair use to use a home videocassette recorder to make copies of television programs and movies for later viewing.
http://encarta.msn.com/encyclopedia_761570404_2/Copyright.html#S17

RE: Crane paper, exchanger

Here's an approach I've used before that basically summarizes the suggestions from a number of the previous posts.

For a single phase, incompressible fluid, the head loss through a fitting is directly proportional to the flow squared assuming the friction factor does not change appreciably...
dP = f(Q^2)

From Crane's TP410 or any other of your favorite fluid flow references

dP = 0.00001799 * K * rho * Q^2 / d^4
dP = head loss, psi
K = resistance coefficient
rho = density, lb/ft3
Q = flow, gpm
d = inside diameter, inches

Rearranging...

K = dP * d^4 / (0.00001799 * rho * Q^2)

Now you still need to have some data to start with such as the manufacturers's calculation results indicating the pressure drop for the designed flow rate or you will have to perform those calculations yourself unless you can actually measure the pressure drop and flow in the plant.

The only part that remains is the diameter but I would just pick that equal to the piping run where the exchanger is located which allows you to sum the resistance coefficient of the exchanger directly with the piping.  Otherwise, the resistance coefficient for a given component in terms of other diameters is related by...
Ka = Kb * (da/db)^4

RE: Crane paper, exchanger

Of course i dont object to exchanging advice here - wheater this is quotes from Crane or any other textbook or not. Im referring to distrubting e.g. photocopies of Crane (or any other textbook) or copies of computersoftware.

I may have misunderstood the question. Even quoting from a limited section seems fine to me instead of buying the whole book just for one paragraph.

Best regards

Morten

RE: Crane paper, exchanger

(OP)
Thanks to everybody. You are the best.

MortenA,

I don´t looking for an illegal copie of Crane or Visual Flow. In my company we have the Process Engineering suites (SimSci-Esscor) License. My trouble is that my company will do not give me money (Here in Venezuela US$ 35 is a considerable amount of money) to buy crane's book only to obtain the K factor to supply Visual Flow requirement.
We have very amount of bibliography of mechanical fluids and they do not will buy another.

Thank you.

LbLópez.

RE: Crane paper, exchanger

Lopez:

I understand your situation in Venezuela and I empathize with you.  I worked and lived in South America for some years and I am very familiar with what it is like to practice engineering there.  However, being a Venezuelan and doing engineering design there may have some benefits unknown to you.  I've had 5 copies of Crane's Tech Paper #410 in my 46 years as an engineer - and all of them were received free from pipe and equipment suppliers here in the USA.  The last one I got was from Vinson Supply Company, out of Dallas.

I don't know what company you work for, but perhaps if you got together with your purchasing department or buyers you might get an idea if they can obtain some free copies for you through their purchasing contacts either here in the USA or there in Venezuela.  There is a lot of fluid flow design being done in Venezuela today; I'm presently working on 2 projects related to projects there.  So I'm very familiar with the quantity and size of B31.3, B31.8, and API 5L piping that is going to be installed.  There are megatons and megasizes in question and consequently there should be some bargaining or leverage position for you and your engineering buddies there to obtain complementary copies through cooperation with your purchasing department.

Buena Suerte y Exito.

RE: Crane paper, exchanger

(OP)
Thank you Montemayor,

I'm a Junior engineer. I am learning. You're rigth, have some benefits still unknown for me.

RE: Crane paper, exchanger

Lblopez,

Es un cambiador de calor de la cáscara y del tubo?  Está usted interesado en el lado del tubo o el lado de la cáscara?

Good luck,
Latexman

RE: Crane paper, exchanger

(OP)
Latexman,

Is a shell and tube heat exchanger. Really, the cooling water system have many heat exchangers (40 approx).

I have all information that you ask me in your past post, in the heat exchangers data sheet, I did a simulation in HEXTRAN to obtain the pressure drop.

I have the pressure drop in both sides, but I need K factor to Visual Flow simulation. I know that is related with pressure drop but I dont have the equation (formulae)
I'm looking for this K factor. ¿You Know how can I calculate it?

Thank you!

RE: Crane paper, exchanger

Lblopez,

Did you check the "Help" section of Visual Flow for their definition of K?  In their documentation they should have an equation for pressure drop with K  defined.  If not, call the person in your company that gives technical support for that software or call Visual Flow's technical support or search their website.

If not, EGT01 did an excellent job above.  Be careful with units (SI or English)!  Different units will change the value of K.

You can estimate the pressure drop (dP) of a heat exchanger with HEXTRAN.  Let's say you want to calculate K for the tube side of a particular exchanger.  For example, let's say HEXTRAN calculates the dP of the tube side of this particular exchanger at 5 psi.  Now you need to take the dP (5 psi) from the heat exchanger evaluation and use it to characterize the heat exchanger as a fitting or pressure drop element in Visual Flow with a K factor.  So, use EGT01's equation for K:

K = dP * d^4 / (0.00001799 * rho * Q^2).

dP = 5 psi
d = the inside diameter of the water piping to and from the tube side of this particular exchanger used in Visual Flow
rho = the density of the water to and from the tube side of this particular exchanger used in Visual Flow, lb/ft3
Q = flow of the water to and from the tube side of this particular exchanger used in Visual Flow, gpm

Take the calulated K and use it in Visual Flow.

*IF* the flow and density of the water to and from the tube side of this particular exchanger used in Visual Flow CHANGES as your simulations in Visual Flow approach reality, you'll need to re-calculate a K for the tube side of this particular exchanger.  It may take a few iterations to a converged solution.

Good luck,
Latexman

RE: Crane paper, exchanger

LBlopez,

Be sure you use the correct units in each equation.  Convert the values and units of each variable into the correct units for an equation before you substitute it into the equation!

Good luck,
Latexman

RE: Crane paper, exchanger

On 19 Jan you mentioned an "exchanger window". If you meant the shell side baffle window you could retrieve an article by Dale Gulley. It was in the June 2004 issue of Hydrocarbon Processing. The title is "More Accurate Exchanger Shell-Side Pressure Drop Calculations". There is an equation for the K factor for the baffle window.  

RE: Crane paper, exchanger

(OP)
Thank you Latexman!

RE: Crane paper, exchanger

(OP)
srfish,

I referred to a window of simulation software.

RE: Crane paper, exchanger

perhaps i did not understand correctly lblopez...

what i understood is:
1.you did the HE pressure drop calculations...
2.you need a K to use in a flow simulation program

if 1 and 2 are correct interpretations of your problem...

you can calculate a "equivalent" K for your HE doing the following calculation:

K = Δp/(ρV^2/2g)

use V corresponding to the pipe diameters connected to the HE...
this will replace the HE with a "virtual length of pipe" that has the same pressure drop as the HE at design conditions...
for small variations of flow (10%~15%), and temperatures this will still give a good approximation.

espero que esto te sirva chamo.

saludos.
a.

RE: Crane paper, exchanger

Why don't you just install a pressure gage on the inlet to the exchanger and one on the outlet of the exchanger and measure the pressure difference and then calculate the K factor from that measurement.

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