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View Full Version : high discharge pressure after replacing the new condenser for 30 gh carrier chiller.





moideen
24-07-2013, 07:29 AM
dear friends,

Yet, I did not visit the site. I have been told on telephone. Chiller model:30gh100,carrier chiller. New condenser coil 15fpi/inner grooved tube was replaced. After commissioning discharge pressure is very high. Client (carrier) is not approved condenser replacement job .After more inspection, again replaced the plane tube condenser coil 18fpi/plain tube for circuit A only. Commissioned with 700micron vacuum and dupont suva refrigerant. Required gas charge as per catalogue 29kg for each circuit. But now not fully charged. Primary readings are below.SP=70/DP=340/LIQUID LINE PRESSURE=310/AIR ENTERING TEMP=40C/LIQUID LINE TEMP =49C/DISCHARGE LINE TEMP=96C.othor readings are not available. Tomorrow I will go to site and full reading update you. Have any comments…….

moideen
26-07-2013, 03:34 AM
Date.



Time



Operating Parameters

CIRCUIT - A

CIRCUIT _ B



Refrigerant

R22




Suction Pressure

65 psig





Saturated suction Temperature.

3.1c





Suction line Temperature.

No avl





Super Heat-compressor(REQUIRED 16C)

30c





Discharge Pressure

330





Saturated cond. Temperature.

57.5





discharge line temp

92C.




Liquid Line Temperature.

54.3





Liquid line pressure

300




Sub Cooling

1k





Pressure drop in high side

25 psig




EXV





Ambient Temperature.

39c





Condenser TD

18k




Condenser approach/LTD

1K




EVAPORATOR TD

10K




Evaporator LTD/APPROACH

6k




Condenser CFM as per catalogue

63199




condenser avg.air veleocity

700FPM AND 529 FPM.




condenser coil face area

30 FT2




Condenser Air In Temperature.

39c





Condenser Air Out Temperature.

56.3





Condenser Air delta Temperature.

17.3c





Chilled Water In Temperature.

13c





Chilled Water Out Temperature.

9c





chilled water Delta T

4k





Chilled Water in Pressure

19psig





Chilled Water Out Pressure

15psig





Chilled Water delta Pressure

3psig





Chilled water flow rate

No avl




Refrigerant Charge approximates

24 kg





Refrigerant Charge as per catalogue

29kg.




Average Volts

380





System Sight Glass

Slightly flashing at exv 100% open





Avg. Amps Comp A1-06E299-CARLYLE

62 A





Avg. Amps Comp A2-06E270-CARLYLE

62 A





Avg. Amps Comp B1-06E299-CARLYLE

46A





Avg. Amps Comp B2-06E270-CARLYLE

46 A





My observation
1. Condenser TD is high-so the condenser is undersized.
2. Condenser air delta T is high-but calculated cfm is matching to the catalogue cfm.
3. Condenser approach is low=so the heat transfer takes place.
4. Sub cooling is very low,as per catalogue minimum need 7k.
5. Chilled water delta T is low, because only two compressors are working, B circuit is shut off.so to be maintained the delta T is 2.5c.
I am again thinking,have you any comments.

moideen
26-07-2013, 06:44 AM
anybody can say, how to design the lower td air condenser?what will be the specifications?can increase fin pitch or row?but it will affect the air way resistance and pressure drop in condenser.

jason09
29-09-2013, 11:15 AM
and a 30psi pressure drop

Magoo
30-09-2013, 12:07 AM
Clarification : an 18fpi coil replaced by a 15fpi coil. If that is correct, coil is short of surface area. Which will directly effect discharge conditions. It will be more evident at high ambient temps.