HTRI learning - Question and Answers

[henj]

how to start with HTRI rating, i mean from start to finish
if requirement is of over design , then go for increasing tube s or shell id ? or any other parameter
where to stop rating ( satisfactorily calculations )
at which stage to start design
please explain with example --- if possible

Start entering all red marked information in the input.. (look in post # 54 - 58 in this thread)
Try some of the examples/samples in HTRI, and experiment by changing the value of the inputs.
Or look in a good book - say in post # 52 in this thread.

To increase the heat transfer / overdesign you may increase flow/velocity (smaller ID shell/tube, less number of tubes, less baffles cut, more baffles ..). Keep a eye at the increasing pressure drop.
You stop calculating when you have satisfactorily transfer, and the heat exchanger is not too big / costly to build and the pressure drop not too high.

[henj]

Is the face velocity for an aircooler too low( 1 m/s) ? What is the lowest limit to consider?

I think it could be too low - usually > 2 - 2,5 m/s at standard conditions.
But it depend on your options, the cooler just get bigger with lower air velocity..

[vne]

Out from the drawing in the sheet I can't see how your baffles could work - they are only in the center? Please upload the HTRI-file.

henj,

Pls refer to the drawing again, it's double segmental baffle with vertical cut.

[henj]

Pls refer to the drawing again, it's double segmental baffle with vertical cut.

Okay it is not easy to see on the drawing, maybe rotate the drawing another time.
Sorry but if one should be able to help you it would be best /easiest to have the HTRI file, as I could not get warning on mine calculation.

I have add mine HTRI file to show.

[sniperel]

Thanks henj for your help.
Can someone have HTRI Report AC-9 (natural draft air cooler) or a material related to this subject?
Thanks a lot!
Best regards!

[biswjeet]

hi everybody
can anyone tells me
for a case ,
1. if in rating or design , without fouling factor i calculate gives result of 3.25% of overdesign & if i put fouing factor( 0.0005 at both side) at both sides it gives result of underdesign of -1.16% --- WHY????????????
2. HOW to make sure that Thermal Resistance % IS OK FOR RATING OR DESIGN ?
They have any concepts to be considered? What % of Shell & other Thermal Resistanc to be ?

[sniperel]

Hy!
It's very simple, adding thermal resistence you decrese heat transfer coefficient, so for the same duty you need a larger area (negative overdesign). For the second question I am afraid I don't know the answer. Hope I helped you. Have a nice day!

[henj]

1. if in rating or design , without fouling factor i calculate gives result of 3.25% of overdesign & if i put fouing factor( 0.0005 at both side) at both sides it gives result of underdesign of -1.16% --- WHY?

What did you expect? Fouling reduce the heat transfer..

2. HOW to make sure that Thermal Resistance % IS OK FOR RATING OR DESIGN ?
They have any concepts to be considered? What % of Shell & other Thermal Resistanc to be ?

As mentioned previously in this thread if the design meet the demand it is okay, but you could try to optimize to save cost.

The procents on shell and tube side could be more or less even if same condition on both side say water in both places. If one side is much bigger (say 25 % higher?) one may look into reducing it by say increasing the velocity on this side to get a smaller Heat exchanger. That is part of the game to optimize this.
But some cases the conditions on the two sides are not even say water and air or say the allowed pressure drop are not even.
To chose the correct Fouling is difficulty in most cases especially if not in a well known service..

Remember that the Design mode in HTRI can be nice to locate new and better options for you..

[biswjeet]

hi every body

can anyone tells me
how to design feed water heater in HTRI
superheater /sub cooler- is we have to consider 3 different exchangers

[mbc.engg]

I am getting following error in HTRI:
"The latent heat specified does not correspond to the latent heat calculated by program based on heat release curve specified for hot fluid. Please check the increment no. 14. The specified latent heat is used in all calculations"

What is significance of the above error? How to resolve this?

[henj]

mbc.engg
It would be easiest to comment on this if you uploaded the HTRI-file for us to look at.

[alekogs]

Dear all,

I am working with HTRI 5.0 and making design calculations for (Isobutane / Brine ) heat exchanger.
When trying to generate properties for hot and cold streams, i am having error for property generator.
- How to set the property package? and eliminate package authorization error?

rgds
Aleko