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.
Attachment 13741
Pls help...if there will be any recommendations pls do let me know.

thank you

Quote:

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Originally Posted by roelescence

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.
Attachment 13741
Pls help...if there will be any recommendations pls do let me know.

thank you

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Water for condenser cooling in 85.3F out 93.1F. Delta T is 7.8F. 93.1F water should go to the tower for cooling. 80.5F cooling water in is wrong number. It should be around 93.1F

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.

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.

:cool:

Quote:

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Originally Posted by roelescence

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.

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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.

I am also suspecting that there must be leaks in the elbow piping which bypasses the water from cooling.

Quote:

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Originally Posted by The Viking

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.

:cool:

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Do you mean 80.5F is not enough to cool down the water in the sump? and is that why I am gaining 85F? How about the entering air of 86F, isnt it also a factor?

Ive just got ΔP for the condenser, 13 PSI ΔP

Quote:

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Originally Posted by roelescence

Do you mean 80.5F is not enough to cool down the water in the sump? and is that why I am gaining 85F? How about the entering air of 86F, isnt it also a factor?

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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

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.

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.

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 :)

Quote:

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Originally Posted by RANGER1

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.

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so in other words, 44°F chilled water can still be attainable with 85.3°F of sump temp if the condenser tubes are clean?

Quote:

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Originally Posted by RANGER1

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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yeah I tried your sudgestion and Ive just found it out that they have thesame reading of 85°F. Now, can we say that something matters is the drybulb temp coming in?

Finally I got this,Attachment 13756
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.

Quote:

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Originally Posted by RANGER1

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.

---

Superheat and subcooling temperature sensors are not available in RTWD 120 ton Trane chiller, how can I manually check the temps?

Quote:

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Originally Posted by roelescence

so in other words, 44°F chilled water can still be attainable with 85.3°F of sump temp if the condenser tubes are clean?

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I would say yes, but that would be close to maximum water temperature