Refrigerant Temperature in the Water/Air Cooled Chiller

[jinx]

HI ALL,
I am studying the COP different between Water Cooled Chiller and Air Cooled Chiller. But it is difficult to find any refrigerant temperature inside the chiller. Anyone can tell me the refrigerant temperature? Therefore, I can draw a P-H diagram and find their different.

Thanks for your help =]
JINX

[nguyenloc178]

i am sorry. i do not help you.

[jinx]

i am sorry. i do not help you.

Thanks for your reply =]

[jinx]

i find some catalogues from trane. but the refrigerant temperature is not stated. they state the chiller water temperature only. =.=" SO BAD

[nike123]

COP doesn't change (if evaporation and condensation temperature are same and power consumption is same) just because use of air or water heat exchanger. Air HE need fan and water HE need pump. If their power consumption is same and evaporation and condensation temperatures remain the same, there is no change in COP.
Evaporation and condensation temperature depend on air and water temperature and TD of heat exchangers. Other temperatures in circle depend on superheat and subcooling at measuring points and heat generated in compressor doing his work. So, in order to know temperatures in parts of refrigeration circle, you need these data.

[jinx]

Thanks=] nike123 =] my duty is to find out these data (temperatures in parts of refrigeration cycle) in order to draw a p-h diagram. In fact, i am not sure the evaporation and condensation temperature are same in different chiller (water cooled or air cooled). And I have not these data to draw =.="

[nike123]

Thanks=] nike123 =] my duty is to find out these data (temperatures in parts of refrigeration cycle) in order to draw a p-h diagram. In fact, i am not sure the evaporation and condensation temperature are same in different chiller (water cooled or air cooled). And I have not these data to draw =.="

What is full description of your task?

[jinx]

my job is draw tow vapour compression cycle. one is about water cooled chiller, another for air cooled chiller. and compare their COP at the end =]

[nike123]

my job is draw tow vapour compression cycle. one is about water cooled chiller, another for air cooled chiller. and compare their COP at the end =]

So, some tutor said to you to draw two P-h diagrams and only data you have is that one is air cooled and other is water cooled chiller. Rest is on your imagination.

Then draw him two same diagrams, he cannot accuse you for anything. Temperatures could be as you like. For example:


As I said earlier, they could be of same COP. Or air cooled could be of higher COP than water cooled. Also, COP is not constant value, it changes with conditions.

How is tutor imagined that you are going to calculate and find out COP with that wast amount of data? Or, you are not telling us full story.

[jinx]

Thanks for your reply =]

My tutor ask my to draw two P-h diagrams to show water cooled chiller has a higher COP.

BUT he did not give me any data about the refrigerant temperature. He just ask me to find such data on the internet and books.

However, I find many catalogs and books which did not tell me the any refrigerant temperature in evaporator and condenser. =.="

[nike123]

OK, i will give you real life data examle from some chillers I worked with, which are enough to find what are you need to draw diagram.
Air to water chiller:
Refrigerant R22
Cooling capacity 46,2 kW
Electrical input 15,8 kW
Evaporation temperature 0°C
Evaporator superheat 5K
Total superheat 8K
Condensation temperature 40°C
Subcooling 7K
LL pressure drop 100 kp
Compressor superheat 40K

This is sufficient to work out all you need to draw diagram. Let see how will you find out all temperatures in cycle.

[jinx]

Thanks. i am finding data like yours. It is very useful. =]

Do you have some data about water cooled chiller ?

Million Thanks =]

[nike123]

Thanks. i am finding data like yours. It is very useful. =]

Do you have some data about water cooled chiller ?

Million Thanks =]

First work out temperatures and COP for this data and post here and then we will discuss about water cooled chiller.
There is no point in learning if you got all on plate.

[Lowrider]

Attached the parts of the manuals for an air cooled and water cooled chiller. By Trane!

Theoretical an air cooled chiller has a lower COP.

@ Nik123:40K discharge superheat would result in 80 dgr discharge temperature! With a screw condensing at 40 that's pretty high!

[nike123]

@ Nik123:40K discharge superheat would result in 80 dgr discharge temperature! With a screw condensing at 40 that's pretty high!

It is two Maneurop scrolls in two separate refrigeration circuits (maybe not best example for student), one is SZ120 S4 VA and other is SZ090 S4 VA and they both have same temperatures. 80°C discharge is normal for them.

[wambat]

HI ALL,
I am studying the COP different between Water Cooled Chiller and Air Cooled Chiller. But it is difficult to find any refrigerant temperature inside the chiller. Anyone can tell me the refrigerant temperature? Therefore, I can draw a P-H diagram and find their different.

Thanks for your help =]
JINX

The term Coefficient of Performance (COP) is simply the ratio of the cooling effect produced expressed in Btu/hr divided by the energy input expressed on the same basis. For an electric chiller at 0.6 kW/ton, this ratio is 12,000 Btu for a ton of cooling divided by the corresponding 0.6 kW energy input. The units of kW can best be thought of as kW hours per hour. Each kW is equivalent to 3,413 Btu, therefore 0.6 kW is 2,048 Btu. Therefore, a 0.6 kW/ton chiller is equivalent to a COP of 12,000 Btu/2,048 Btu, about 5.9 COP. Notice the term COP is dimensionless.


The COP considers the refrigerating effect and compressor power only. This doesn't include other power consumption. However, if you want to calculate specific power consumption of entire system, for the same tonnage you should work out on the following details

Air cooled chiller
Compressor power consumption
Condenser fan power consumption

Water cooled chiller
Compressor power consumption
Cooling water pump power consumption
Cooling tower fan power consumption
Cost of make up water
Cost of chemical treatment. You could find that the water cooled system has a lower total COP then the air cooled.

[THE WOMBAT]

Buy chiller with hot water output or fit a plate heat exchanger to discharge to harvest off the discharge heat will increase COP as well.

This is far more efficient than any VRV or water cooled condenser system..
I thinks there will be a upcoming trend in high discharge temp chillers with hot water output and air condenser fans.

The amount of wastage in system designs is becoming tighter through gov regs soon to bite us in the (l)

I know one of my data centre's as 1.5Mw of of heat blowing out the side of it. I'm trying to talk the boss into hooking up the neighbourhood into a central heating project, i could get 1/4 of the power bill back in heating bills $$$$$$