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03-11-2017, 09:53 PM #1
most efficient way to supply ammonia to lowside recirculator
Not sure if this has been asked before, but see following description.
2 stage ammonia refrigeration plant
-40 C low side with liquid recirculator pumps
-10C intercooler/recirculator with liquid pumps
Several ways to maintain -40C liquid level
1/ high pressure liquid from receiver subcooled by separate internal coil in -10 C then feeds -40 C
2/ low pressure liquid transfer from -10C to -40C
3/-10 C liquid pump feeding -40C
4/ other methods don't know or can't think of on 2 stage plant
2 & 3 the same efficiency
What would efficiency difference be between 1 compared to 2 or 3, much?Last edited by RANGER1; 04-11-2017 at 01:07 AM.
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04-11-2017, 03:23 PM #2
Re: most efficient way to supply ammonia to lowside recirculator
1 is less efficient than 2 and 3, but difference is not significant. In 2 and 3 temperature of the liquid which is going to -40C vessel is -10C. In 1 this temperature is slightly higher probably from -5C to -7C. Evaporation temperature is intercooler is -10C and temperature of subcooled liquid will be higher than evaporating temperature.
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04-11-2017, 05:34 PM #3
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Re: most efficient way to supply ammonia to lowside recirculator
Hi
as Segei told in 1 we have less efficient ( sub-cooling liquid )
But between 2 and 3
in 3 we have a little more efficient than 2 because of pump pressure .
also at 3 ) if we need more liquid in -40 it is better we use this feeding.Last edited by mbc; 04-11-2017 at 05:37 PM.
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04-11-2017, 09:14 PM #4
Re: most efficient way to supply ammonia to lowside recirculator
Thanks, I sort of figured some difference, it not significant.
A bit more flash gas on high pressure subcooled liquid that has to be compressed twice.
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04-11-2017, 10:19 PM #5
Re: most efficient way to supply ammonia to lowside recirculator
Hi mbc.
I don't see efficiency difference between 2 and 3. However, I agree with liquid feeding from intercooler to -40C vessel. To supply liquid in 2 example we have pressure difference around 30 psig. However, saturated liquid will be supplied. It means any pressure drop in liquid line will create flash gas and this gas will reduce capacity of metering valve. In 3 example liquid pump increase pressure difference to 60-80 psig and liquid will be subcooled. It means no flash gas in liquid line. Liquid pump will be able to supply 3-5 times more liquid to -40C vessel than just pressure difference.
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05-11-2017, 02:47 PM #6
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Re: most efficient way to supply ammonia to lowside recirculator
Hi
if you see this PH diagrams you can see a little more efficiency
1111.gif
From 6 to 17 is a our pump pressure
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05-11-2017, 04:38 PM #7
Re: most efficient way to supply ammonia to lowside recirculator
First, difference between 2 and 3 is fraction of 1% because of energy added by the pump. Second, 2 is more efficient(less flash gas) than 3 but difference is minimal.