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25-02-2008, 09:21 PM #1
ammonia (NH3) condensers selection
Hi all! I am a student from Portugal i am currently frequenting a masters in refrigeration climatization and energy. In on of the subjects i have this semester (refrigeration) we have to project a warehouse for fish conservation this warehouse is formed by 3 principal rooms a fast frizzing room a preparation room and a frozen fish conservation room.
All the loads calculations are made (thermal balance)
the fluids are:
Ammonia (NH3) and glycol
Is there any software that could help me selecting the ammonia condensing units?
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25-02-2008, 10:36 PM #2
Re: ammonia (NH3) condensers selection
Hi, joaocruz
Welcome to RE forums....
we also have one forum: New to RE for first post to introduce yourself
Anyhow, please try those links:
Handbook
http://www.baltimoreaircoil.com/engl...book/index.php
Software
http://www.baltimoreaircoil.com/engl...s/ec/index.php
You can search Evapco site for another software....
One more excellent software CoolPack: need registration but it is free
http://www.et.web.mek.dtu.dk/Coolpac...-download.html
....hope this will be of some help to you
one more thing...searching RE forums you can find a lot of links to different info...books, software, etc...just try
Best regards, Josip
It's impossible to make anything foolproof because fools are so ingenious...
Don't ever underestimate the power of stupid people when they are in large groups.
Please, don't teach me how to be stupid....
No job is as important as to jeopardize the safety of you or those that you work with.
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25-02-2008, 10:47 PM #3
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Re: ammonia (NH3) condensers selection
For those who are terrified of registration of any kind, there is link for direct download of CoolPack great and free software: http://tinyurl.com/3yt3w3
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25-02-2008, 10:49 PM #4
Re: ammonia (NH3) condensers selection
Originally Posted by joaocruz
Are you going to school to learn how to use software or to learn how to do engineering?
Almost all ammonia systems are custom engineered to the specific operating conditions and capacity requirements. If you know your cooling loads and operating conditions we might be able to assist you (a little bit, after all you are the one trying to learn this).
Shortcuts using any software should only be used by experienced engineers, not by someone trying to learn. I say this because you will not have any feeling for answers generated by the software.
Unfortunately, the only way to develop this understanding is to do the math yourself.If all else fails, ask for help.
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25-02-2008, 10:56 PM #5
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Re: ammonia (NH3) condensers selection
Last edited by nike123; 25-02-2008 at 10:58 PM.
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25-02-2008, 10:59 PM #6
Re: ammonia (NH3) condensers selection
Just as you would not use a screw driver when you need a chisel.
If all else fails, ask for help.
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25-02-2008, 11:15 PM #7
Re: ammonia (NH3) condensers selection
Hi, US Iceman
I will not bet on this....you must know what Einstein said about endless things....
Originally Posted by Albert Einstein
Originally Posted by joaocruz
Best regards, Josip
It's impossible to make anything foolproof because fools are so ingenious...
Don't ever underestimate the power of stupid people when they are in large groups.
Please, don't teach me how to be stupid....
No job is as important as to jeopardize the safety of you or those that you work with.
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25-02-2008, 11:19 PM #8
Re: ammonia (NH3) condensers selection
for the conservation (freeze fish) room the conditions are:
Dimensions 20*60*7.5 m
outside conditions: t=35ºC and HR (relative humidity 50%)
Temperature -25ºc
entering product temperature : -15ºc
Relative humidity 50%
daily product entry 8% of the volume
density of occupation 350 kg/m3
compressors work 18H day
load to remove (evaporators) : 140.7 Kw affected by 20% coefficient regarding the heat produced by the motors actuating the fans of the evaporators
I am considering the installation of 5 evaporators
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26-02-2008, 01:25 AM #9
Re: ammonia (NH3) condensers selection
If the heat load is 140.7 kW then you have to add the 20% (of the fan motor heat) to the cooling load. The evaporators have to cool the heat load plus the fan motor heat.
Then you will have defrosts. A rough rule-of-thumb is if you have 4 defrosts per 24 hours, then the cooling time (24-4=20) available to meet total heat load increases the minimum required capacity of the evaporators. This assumes the total defrost cycle is no greater than 1 hour.
What you will end up with is something like this:
(140kW *1.20) / (20/24) / 5 evaporators = 40.3 kW per coil.
Therefore, when one coil is in defrost the other coils can still provide sufficient capacity to meet the cooling load.
Now, if your room temperature is -25C, then this means your evaporating temperature has to be colder for the evaporator to work.
Room temperature - evaporating temperature = degrees of temperature difference to select evaporator.
Since you will have pressure loss through the suciton line (from the evaporator to the compressor suction) you have to account for the pressure loss.
Did the professor address any of the above?If all else fails, ask for help.
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