Design of heat exchanger step :2 : which type?

5 CommentsTechnical
The next step is to decide which type of exchanger to be used?
The industrial heat exchanger are varies depending upon
1. Transfer process.
2. Number of fluids
3. Compactness.
4. Constriction.
5. Flow arrangement.
6. Type of heat transfer.
See attached figure for more details.

Heat exchanger: step 1: application

1 CommentTechnical

<p>The first step dorm designing a heat exchanger is to understand where it will be used for.</p>
<p>Application is most important criteria and mostly its input from client.</p>
<p>Application demands understanding of functionaries expected, duty needed, properties of both side fluids, system information e.g presuredrop expected, cleaning method of the equipment, hazard category, local laws pertaining to pressure vessel and hazard handling.

Some time the application demand ‘soft’ heat transfer due to the media e.g yeast cooler due to delicate yeast cells are always co-current type which lead to higher surface area and are more costly than counter current heat exchangers; but due to application those are designed that way.

What is heatexchanger?

GoodRead

Yup, just a brief on this subject.

Heat exchangers are devices used to transfer heat energy from one fluid to another, gas to gas or gas to liquid. 

Typical heat exchangers are seen around in most unexpected location. From household appliances as air conditioners, refrigerator etc.  Boilers and condensers in thermal power plants are examples of large industrial heat exchangers. There are heat exchangers in our automobiles in the form of radiators and oil coolers.  Heat exchangers are also abundant in chemical and process industries.

Heatexchanger sizes varies from couple of square mm (heat sink in computer cpu) to length exceeding hundreads of square meters!

From simple study flow to complex flows.

Heat exchanges as they say “comes in all sizes and nearly for all duties”

We will, in my next post discuss about fundamental of heat exchangers.


Heat exchanges… Google way.

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If you Google the word you will get morecthan a billion results. That just shows how it closely associated to industry, to us.

But at the same time ut shows how wast  the subject is.

The purpose of next few blows is to simplify your search by telling you what to ask and where to see.

Figures crossed 🙂

HEAT EXCHANGERS

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Past few months I was thinking of creating a post on heatexchangers. I think now is the time when i can write a bit on this subject.  

There are numerous sites available which will explain verwell about this subject. But as usual they lack the subject matter. What we all are interested in. The core, the ‘how’s part of it.  

In my next few pposts you fand this information.

Take care.

Heads as per ASME : Quick overview

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I was studing some heads for a while, and thougth to summarise the variety in one go…

1.      Flanged Head : Normally found in Vessel opertaing at low pressure, genrally water tanks, Boilers etc. They are also used in high pressure application where the diameter is small.
2.      Hemispherical Head : Generally, the required thickness of the hemispherical head due to a given Pressure & temperature is half of cylindrical shell with equivalent diameter & Material.
3.      Elliptical and Torispherical (ASME Flangged & Dished) heads : they are very popular in pressure vessel, their thickness is ususally same as the cylinder to which they are attached.

This is a quick heads up for variety of heads used in industry. The other type are
1.      Conical or Toriconical head: they mostly form bottom end closure for the vessels, and act as hopper, or to give easy drainability. The important thing to consider while designing this heads are, a) they increase the overall height of the vessel. b) ASME need to do discontinuity analysis for half angle >30 deg, or else one need to go ahead with toriconical head to avoid the unbalanced force at the junction.
2.      Miscellaneous head: Many chemical process requires unusual vessel configuration, the heads of such vessel can have unlimited configurations. The design of such head is very complicated, and there is no straight forward formula for that.

Keep reading!

Project Management Performance Analysis

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Good read for Project management performance analysis.

 

http://en.wikipedia.org/wiki/Earned_value_management

 

Keep reading!

Great Space Exploration Tool

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Wonderful website!

 

http://celestia.sourceforge.net/

 

 

Keep Watching!

Process Piping Pressure Calculation : B31-3

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B 31.3 is an ASME code for Process piping, Multiple time we come across situation, where we need to calculate the design pressure for a pipe.

 

In such cases, ASME VIII-Div-1 seems helpless, and B 31-3 comes for rescue.

 

Clause 304.1.2 talks about Straight pipe under internal pressure,

 

 

Where,

P > Internal design pressure

D > Outside diameter of pipe

S > Stress value of material as per table A-1

E > Quality factor from Table A-1A & -1B

Y > Coefficient from table 304.1.1

 

Compare equation 3a with ASME VIII-1 Formula (UG-27)

The formula is completely same, except factor PY against 0.6 P!

Y factor varies from material & Temperature, which varies from 0.4 to 0.7

 

As I’m working on one of the project, where I’m manually doing calculation, I thought this will be fastest way to share!

 

Keep reading!

 

Code Comparison : Discussion:1

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Scope & Responsibility:

Let’s start with comparing the scope & Responsibilities for various codes.

Following table will give an overview

Characteristics

ASME VIII-Div-1

EN 13445

GB-150

Scope

Ref ASME VIII-1 U-1   

Pressure Not exceeding 20 MPa U-1(d)

Design by Formula

Minimum pressure 15 psi (g) [1 bar(g)]  

Minimum -ve pressure 15 psi (g) [1bar(g)]                                              

Refer EN 13445-1: 2009

No limit on pressure

Design by Formula & Design by Analysis

Minimum pressure 0.5 bar(g)

Minimum -ve pressure -0.5 bar(g)

Refer GB-150 : 1-1.1

Pressure not exceeding 35 MPa

Design by Formula

Minimum pressure 1 bar(g)

Minimum -ve pressure 0.2 bar(g)

Responsibility

Ref VIII-1 U-2 (b), UG-90

Responsibility of Manufacturer to design complete

vessel as per requirements of Code

19 responsibilities with Manufacturer, 14 with AI

Refer EN 13445-1: 2009

Responsibility of Manufacturer, counter signed by

notified body (Independent agency)

Annex – H to be filled & Signed

GB-150 : 3, Clause 3.2.2

Responsibility of Manufacturer & Designer to design

complete vessel as per requirements of Code

Next Topic Material & Properties!

Keep Watching!