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View Full Version : R134a to R407C



tooltemp
15-05-2008, 01:50 PM
Hi
I'm looking at a job where the packaged water chiller is running on R134a. The chiller has 4 off MTZ160-4 Manurope compressors fitted, running as two circuits. Air cooled condensors and 2 plate heat exchangers. Internal ciculation pump and process pump.

The ciller is being used to cool the hydraulic oil on a press. The press is fitted with a 185kW process motor and a 5.5kW recurculation motor.

We have already decided that the 2 heat exchangers fitted are too small. However there is a concern that the ciller also does not have enough capacity so I'm considering changing it to R407C.

Perameters at the moment on 134a are:

Evap Temp - 6.5'C
Condensor Temp - 50.0'C
Measured super heat - 10'C
Set point-11'C
Acutal temp - 12.6'C
DT on flow & return - 5'C
Flow rate to process - 227l/min

What sort of gain in duty could I expect from changing to R407C? Also I know I will need to change the TEV orifices, any thing else that would need to be changed?

Lots of questions I know, but any help would be great.

Thanks

SteinarN
15-05-2008, 03:04 PM
Those compressors have a capasity of 24,2 kW each at 6/50*C, 10K superheat and zero subcool with R134A. Power consumption 8,1 kW each.

With R407c you get 37,2 kW each at 8/52*C dew point. Power consumption 13,2 kW each.

An other alternative is R404a. Capasity 36,4 kW and power consumption 14,9 kW each at 5/50*C.

You need to increase the capasity of both the evaporator and the condensor.

What is the in/out temp of the oil at 6,5*C evaporating?