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nh3simman
22-03-2007, 01:46 PM
A local manufacturer wants to quote for transport refrigeration in Dubai.

With air cooled condenser at 40degC ambient and container temperature at -20degC, thats quite a lift for 1 stage.

What refrigerant is best for these types of applications?

NoNickName
22-03-2007, 01:59 PM
Bock FKX50/775N for refrigerated transport, Te=-25°C, Tc=60°C, Tsuction=-15°C, COP=0.80 with R134a

nh3simman
22-03-2007, 02:38 PM
Bock FKX50/775N for refrigerated transport, Te=-25°C, Tc=60°C, Tsuction=-15°C, COP=0.80 with R134a

Thanks NoNickName, I thought of the Bock and downloaded the FKX catalog from their web site.

The COP is low, is 2 - stage not an option here?

NoNickName
22-03-2007, 03:11 PM
Yes it is. Costs are little higher, though.

US Iceman
22-03-2007, 03:24 PM
What about R-507? I was under the impression this was a replacement for R-502, and R-502 systems used to operate in these conditions (or similar to) for many years with conventional equipment designs.

NoNickName
22-03-2007, 03:48 PM
I think R507 would not be compliant to max allowable pressure on high side at that Tc.

Gary
22-03-2007, 04:06 PM
A local manufacturer wants to quote for transport refrigeration in Dubai.

With air cooled condenser at 40degC ambient and container temperature at -20degC, thats quite a lift for 1 stage.

This doesn't strike me as an unusual lift. A bigger condenser perhaps, and a suction/liquid heat exchanger for sure, but nothing here that would warrant a second stage, IMO.

US Iceman
22-03-2007, 04:51 PM
I think R507 would not be compliant to max allowable pressure on high side at that Tc.


I know. It's higher than R-134a, but this is really not much different than the old days with R-502 and air-cooled condensers.

R-507 is slightly higher than R-502 (based on memory), but the air-cooled condensers and other equipment should be able to operate under these conditions.

NoNickName
22-03-2007, 08:53 PM
I don't know what is the max PS in South Africa. Definitely impossible to use in EU at that Tc.

Latte
22-03-2007, 10:13 PM
How about just buying a Thermo king Magnum
R404, unit SHOULD !!!! work in ambients up to 50 degrees. i am sure carrier must have an option but just trying to keep reeferjon happy
www.thermoking.com/tk/index.asp?region=euromideafrica

Regards

Raymond

nh3simman
25-03-2007, 07:18 AM
If I look at R507A,

http://www.coolit.co.za/images/SmallMollier507A.png

It is probably a bit close to critical. But, look how the characteristic of the gas squeezes the refrigerating efffect.

I guess in any event, you are constrained by the compressor manufacturers choice.

NoNickName
25-03-2007, 12:36 PM
How about just buying a Thermo king Magnum
R404, unit SHOULD !!!! work in ambients up to 50 degrees. i am sure carrier must have an option but just trying to keep reeferjon happy
www.thermoking.com/tk/index.asp?region=euromideafrica (http://www.thermoking.com/tk/index.asp?region=euromideafrica)

Regards

Raymond


the fact that thermoking does it, it doesn't mean it either works or it's the best thing to do. I remember Carrier is doing Free Cooling by pumping refrigerant in the condensing coils during winter time :eek::D:D:eek::rolleyes:

star882
26-03-2007, 01:36 AM
the fact that thermoking does it, it doesn't mean it either works or it's the best thing to do. I remember Carrier is doing Free Cooling by pumping refrigerant in the condensing coils during winter time
Make sure the refrigerant can flow from condenser to evaporator by gravity, then install solenoid valves across compressor and expansion valve. Open the valves and there's your heat pipe...

nh3simman
27-03-2007, 11:12 AM
I don't know what is the max PS in South Africa. Definitely impossible to use in EU at that Tc.

What is PS?

NoNickName
27-03-2007, 11:51 AM
Make sure the refrigerant can flow from condenser to evaporator by gravity, then install solenoid valves across compressor and expansion valve. Open the valves and there's your heat pipe...


Yeah, sure.
Aren't we interested in reducing the refrigerant amounts in chillers?
Isn't refrigerant taxed per Kg in Danmark and Norway?
What about a refrigerant loss?

For nh3simman: PS is service pressure, the max pressure allowed by national or international regulations.