PDA

View Full Version : Condensing Unit selection ?







nbnbn
28-06-2016, 02:37 PM
Can someone help me to select the right condensing unit that fulfills the following specification :

Capacity=.8 KW (I think it's too low put my application to cool 5 litres of antifreeze to -20C)

Evaporating temperature=-25C
Condensing temperature=40C

Superheat=10
subcooling=10 these two are recommendations and can be changed if I am wrong?

I am using coolpack to get the cycle information for R-22 and R404A

The Refrigerant: R22
Data:
Te [C] = -25.00
Tc [C] = 40.00
DT subcooling [K] = 10.00
DT superheat [K] = 10.00
Isentropic efficiency = 1.00
-------------------------------------------------
Calculated:
Qe [kJ/kg] = 165.098
Qc [kJ/kg] = 219.861
W [kJ/kg] = 54.763
COP [-] = 3.01
Pressure ratio [-] = 7.630


Refrigerant: R404A
Data:
Te [C] = -25.00
Tc [C] = 40.00
DT subcooling [K] = 10.00
DT superheat [K] = 10.00

-------------------------------------------------
Calculated:
Qe [kJ/kg] = 115.920
Qc [kJ/kg] = 158.189
W [kJ/kg] = 42.270
COP [-] = 2.74
Pressure ratio [-] = 7.266
-------------------------------------------------


As you can see the cop for R-22 is higher and it's price is much less than R404A
but when I go to http://www.embraco.com/catalog/Default.aspx?language=EN
to select a condensing unit as they are available in my country if found the evaporating temperature for R22 is ranging from -15 to 10C ?

Can someone please help me cause I am not an expert if something i don't understand please tell me.

chemi-cool
28-06-2016, 03:02 PM
I think this unit will be ok for your application - UC UNT2180GK 220V/50Hz 515301512

I would use 507 as refrigerant, you can use also 22 with the same condensing unit.

nbnbn
28-06-2016, 03:20 PM
Thank you for your answer I really appreciate.

In the product specification, the refrigerant is 404A is that alright? Can I use another refrigerant while the specification recommends a specified one?

One more think if you excuse me
do you use the website (http://www.embraco.com/catalog/Default.aspx?language=EN) for selection or you go to pdfs catalog?

chemi-cool
28-06-2016, 07:01 PM
You can use 404, 507 or 22. Just make sure that oil is POE. With 22 you will get lower discharge pressure.

I use my supplier web page for selection.

Good luck with your project.