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Join Date: Apr 2009
Location: Mumbai
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Shell and Tube Evaporator

06/03/2009 12:34 AM

Can we use same design of Shell & Tube Evaporator for R22 & R134a?

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#1

Re: Shell & Tube Evaporator

06/03/2009 7:23 AM

Yes.

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Location: England
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#2

Re: Shell and Tube Evaporator

06/04/2009 4:14 AM

Hi

As per guest you can, however dont forget that the duty will be different for the refrigerant used and you must ensure that any seals or gaskets are compatible with the system oil.

134a will be using alki benzle oil whilst 22 will be most probably on some form of mineral oil

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#4
In reply to #2

Re: Shell and Tube Evaporator

06/04/2009 12:27 PM

Good answer sir, but i wanted to know about the heat transfer area of the heat exchangers used for R22 & R134a.

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$hekhar
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#6
In reply to #2

Re: Shell and Tube Evaporator

06/04/2009 4:48 PM

R-134a uses polyol ester oil. As for the capacity differences and application, contact the manufacturer and give the model and serial number. Tell them what you wish to do and they should have all the information on hand. Most shell and tube evaporators are designed to work with multiple refrigerants. The refrigerant used will affect capacity.

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#3

Re: Shell and Tube Evaporator

06/04/2009 9:55 AM

Please refine your question .

The exchanger design must be modified to incorporate the different mass flows of each refrigerant for a given cooling load. R-22 operates at a higher pressure than R134a and mechanical design must consider the higher design pressure.

The viscosities and thermal conductivities of the two refrigerants are vey similar. However, lubricating oil carried in the vapor return is significantly different. This has significant impact on the heat transfer coefficient in the condenser on th erefrigerant side. The developers of R-134a have published lots of design data needed for that product and comparing it to the other common refrigerants (R-12, R-22, R-504, R-410)

You need to refer to those data for design of the evaporator and condenser coils.

So, my answer is: Yes, and NO!. The same principles apply, but design details must be modified because the different refrigerant systems do behave differently.

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Keith E Bowers, PMP
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#5
In reply to #3

Re: Shell and Tube Evaporator

06/04/2009 12:32 PM

got your point sir.

my question is how to attain a surface area required for a heat exchanger for specific tonnage. i.e for 1TR what will be the surface area required for shell and tube heat exchanger (condenser & cooler) for R22 refrigerant for 5Deg Delta T for air conditioning application for 12deg CHW in & 7deg CHW out?

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$hekhar
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#10
In reply to #5

Re: Shell and Tube Evaporator

06/05/2009 4:59 PM

You may find your answers in the ASHRAE design manuals.

First you must be a member for $600.00 per year. Then the answers are free from there on out as long as you can read and calculate proper formulas and have good input to do so.

Or go to you local library and get a book on chemical engineering and load coefficients.

After that it is a cake walk.

http://en.wikipedia.org/wiki/1,1,1,2-Tetrafluoroethane

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#11
In reply to #10

Re: Shell and Tube Evaporator

06/07/2009 1:46 AM

thanks

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$hekhar
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#7

Re: Shell and Tube Evaporator

06/04/2009 8:14 PM

Are you serious--are you asking we design the heat exchanger for you --for free? Go fish

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Keith E Bowers, PMP
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#9
In reply to #7

Re: Shell and Tube Evaporator

06/05/2009 12:28 AM

OK Sir, Then the charges

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$hekhar
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#8

Re: Shell and Tube Evaporator

06/04/2009 9:31 PM

This isn't a homework problem for school, is it? We frown on students wanting us to do their homework.

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