8 replies to this topic

[karthick selvaraj]

Hi,

Can any one please let me know is it mandatory to provided window cut's in the support plates provided for Floating Head & U-Bundle Exchanger and exactly what is the purpose for providing the window cut.

Although we are giving window's for support plate in most of occasion but still what could be the exact reason.

[srfish]

When you say "support plate", are you talking about the partial plate in a floating head exchanger that is located near the floating tubesheet? I believe its purpose is to support the floating head. There would be no such thing in a u-tube exchanger. Please explain more about your question.

[Dipankarc84]

The window cut is mandatory for a floating head to provide a path for the shell side fluid across the support plate to the end of the head. However, a window cut is not mandatory for a U-tube exchanger and it may cause problems as it increases the unsupported length of the tubes and brings in a whole lot of vibration issues. It is however, employed in certain circumstances when the designer wants to take advantage of the heat transfer surface of the tubes in the U- bend region. If the end support plate comes without a window cut, the U-bend would not contribute to heat transfer and hence considerable amount of area is lost.

[karthick selvaraj]

Hi Mr.Srfish,
First thanks for your reply. To be more clear I am attaching the reference drawing link of U-tube bunde with support plate. if you refer the below link there will be support plate provided near u-bend.

My question is as follows,
Is it mandatory to provide window cut or not in the support plate of U-bundle heat exchanger.

http://www.google.co...eaweSVBg&zoom=1

[srfish]

It is not mandatory to provide a full support baffle at the u-bends.But as it mentions in TEMA, if the bend diameter + the straight length through the baffle cut to the next baffle exceeds the TEMA limitation, then special provision has to be made. One solution is the full support plate.

[karthick selvaraj]

Hi Mr.Srfish.

Yes i accept it is based on the unsupported tube length but my question is it mandatory to provide window cut on the support plate or not. If it is mandatory then why it is mandatory and if not why it is not required.
In many licensor's or owner specification it is mentioned that window cut to be provided in support plate such that 50% of tubes to be supported in the support plate.

[karthick selvaraj]

<sub>Hi Mr, Dipankar,

Let me thank you first for your reply.

I am having doubt on the necessity of providing window cut on support plate. My query is as follows.
Is the window cut provided for support plate in floating head exchanger is to allow the fluid to participate in heat transfer between the support plate and floating head or for any other reason.
Can you pleae let me know.

And as you said window cut in support plate for U-tube budle is provided to make the U-bend portion to participate in heat exchange,I am having a doubt on that.
In HTRI while designing U-Tube heat exchanger, what has to be done in input so that the U-bend portion also to be considered in heat transfer area.
Is it dependent upon the nozzle location, for the above purpose whether the nozzle has to be located after U-bend or someother point is there.
Can you please let me know.</sub>

[Dipankarc84]

Hi Karthick,

In a floating head exchanger the window cut is required, or else most of the tube area behind the support plate is lost.

In a U-tube exchanger however, it would not be a good idea to take credit of the area in the U region, as the flow through the window is a single channel flow and the HTCs in the U-bend area will be lesser than the other regions. Though this area will contribute to higher heat transfer, it would not be advisable to consider it during thermal rating. The second purpose of the window cut in U-bend is to provide sufficient circulation in the U-bend region to avoid stagnation and consequent fouling issues.

If you do not specify a "full support at U-bend", HTRI automatically considers the entire area for heat transfer. However, if the actual exchanger just has a window cut with a support, it is not recommended to account for the additional area.

[karthick selvaraj]

Thanks all for your reply

Thanks
Karthick