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Thread: System Effeciency
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03-05-2015, 12:04 PM #1
System Effeciency
Looking at the picture diagram, I could say that the reason why the chilled water is 53^F is because the entering water in the condenser is 85.3^F which gives Delta T of 7.8^ and I think it's normal for Trane R series chillers, but why is that the cooled water in the cooling tower from 80.5^F becomes 85^F in its basin or let me call it reservoir. Pls observe the picture. is it because the air in temperature is high or the tubes in the condenser are fouled.
IMG_20150503_182357.jpg
Pls help...if there will be any recommendations pls do let me know.
thank youLast edited by roelescence; 03-05-2015 at 12:05 PM. Reason: missing photo
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03-05-2015, 01:57 PM #2
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03-05-2015, 02:55 PM #3
Re: System Effeciency
Ok I mean, 80.5F is the water cooled already by the cooling fan. From the chiller, it was 93.1F, as it passes through the coils in the cooling tower it becomes 80.5F but when it mixes with the water in the reservoir it becomes 85F and will be fed to the chiller back again.
Last edited by roelescence; 03-05-2015 at 02:57 PM.
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03-05-2015, 08:00 PM #4
Re: System Effeciency
OK,
For a cooling tower to perform that badly you will need to have high humidity, the cooling tower works towards the wet bulb temp (either measured or calculated from dry bulb temp and humidity).
But then comes the question of why you are gaining so much heat in the sump.....
Too much water in the sump resulting in low exchange rate?
Poorly insulated sump?
Sump in direct sunlight?
And always remember to make sure the fill pack and drift eliminators are clean, any fouling there will severely affect the performance.
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03-05-2015, 09:08 PM #5
Re: System Effeciency
You should give us more info about reservoir. It looks like only portion of condenser cooling water at 93.1F going to the tower and the rest going back to reservoir. Based on this portion 80.5F water(which when to tower) mix with 93.1F water(which didn't go to the tower) and result is 85F mixture.
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04-05-2015, 01:51 AM #6
Re: System Effeciency
I am also suspecting that there must be leaks in the elbow piping which bypasses the water from cooling.
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04-05-2015, 01:57 AM #7
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04-05-2015, 05:09 AM #8
Re: System Effeciency
Ive just got ΔP for the condenser, 13 PSI ΔP
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04-05-2015, 07:01 AM #9
Re: System Effeciency
1. The sump should be at the same, or at least very close to, the temperature of the water dripping in to it.
2. The entering air temperature is a great factor, just not the dry bulb temperature. When we are looking at cooling towers we need to look at the wet bulb temperature which, depending on the humidity, will be well below the dry bulb temperature. For more in depth explanation of the difference: Click HERE
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04-05-2015, 11:13 AM #10
Re: System Effeciency
roelescence,
The way I understand it is chiller cooling water is not cold enough 53F (11.7 C) & you would like 44F(6.7C).
Condenser cooling water circuit water return 93.1 F (33.9C).
Sump temp of tower 85.3F (29.6C).
Does not look to bad does it for tropical climate, or lets say not enough to upset performance of chiller!
Basics would be clean condenser tubes & check divider plates & gaskets in end covers, if corroded allowing water bypass then repair.
Check cooling tower sprays & water distribution, so no bypass over fill.
What are the conditions of chiller suction & discharge pressures, refrigerant type & suction superheat.
Also chiller water in/out temps.Last edited by RANGER1; 04-05-2015 at 09:32 PM.
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04-05-2015, 09:15 PM #11
Re: System Effeciency
The 80.5F water coming off fill, how did you measure that temp?
Suggest capture it in a small container let water run over it awhile,
then measure it's temp with insertion probe, see if same as sump temp.
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05-05-2015, 08:16 AM #12
Re: System Effeciency
Hi, roelescence
maybe I am wrong, but in above schematic diagram something is missing
... return hot water from HE-condenser should come into the cooling tower from the top ... that line is missing and not into the sump as is shown ....
if the drawing is correct you have just bypass cooling tower and you return the same warm water back to condenser ...
please, if possible, to recheck all piping (and upload whole scheme) to water pump/s, cooling tower, condenser, make up lines, drain lines etc ... we need a whole info to be able to help...
Best regards, Josip
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10-05-2015, 07:49 AM #13
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10-05-2015, 08:15 AM #14
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10-05-2015, 09:23 AM #15
Re: System Effeciency
Finally I got this,IMG_20150510_161451.jpg
Pls correct me if I am wrong.
From there I got two suspects of the unefficient chiller, these are air temp and fouled condenser tubes.
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11-05-2015, 04:25 AM #16
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11-05-2015, 01:02 PM #17