Case Study: Inline condenser cleaning system for 350 TR chiller. -

Area of Improvement:

350 TR Screw chiller, with refrigerant as R134a was in operation. Chiller inlet and outlet temperature was designed for 12 deg C and 7 Deg C. variation in cooling water temperature was from 22 deg C to 32 deg C.

Cooling tower water treatment program was well maintained. Condenser cleaning procedure was in place for 6 monthly which was reduced to quarterly for getting energy saving at compressor.

Observation:

Logbook of chilled water system was well maintained and it was found that after cleaning of condenser, approach (Refrigerant saturation temp – cooling water outlet temp) of system goes down to even 1 deg C and slowly increased from 1 deg C to 7 Deg C in 3 month time. There was SOP in place which says refrigeration system should not be run above 10 deg C approach and condenser cleaning work to be initiated.

It was also observed that being R134a refrigerant every deg C rise in the condenser saturation temperature, There is drop of 3.2% of efficiency. This efficiency drop per deg C was referred from OEM operational manual.

Energy Conservation Measure:

As the temperature was gradually raising in the condenser post manual condenser cleaning over a period of time, also production loss because of shutdown requirement of 4-5 Hrs for condense cleaning. It was decided to go for online condenser cleaning system.

Sponge rubber ball based condenser cleaning system was installed with fixed timer initially for 15 mins cycle and after few days it was increased to 1 hr operation cycle. Before and after approach of chiller was captured after installation of inline condenser cleaning system as shown below:-

Graph of condenser approach before and after

It was observed that even if the chiller condenser was cleaned on quarterly basis, The approach slowly increases from 1 deg C to 7 deg C, the average condenser approach was 4.2 Deg C. After installation of inline condenser cleaning system we have observed there is consistency in the condenser approach and avg approach was recorded as 1.8 Deg C. This was 2.4 Deg C lower than cleaning condenser in quarterly basis.

As being R134a refrigerant based system, efficiency loss because of raise in the condenser pressure wass 3.2 Deg C. Being lower approach and getting difference of 2.4 Deg C in the condenser approach have saved 7.7% of power consumption at compressor motor.

From chiller to chiller efficiency and energy saving will differ based on refrigerant used ,type of compressor, the water quality and rate of fouling. Apart from energy saving. We got major benefit on shutdown requirement of chiller and elimination of manual cleaning activity.

Payback of inline condenser cleaning system was less than 10 months.

Limitation:

Limitation of inline condenser cleaning system is balls needs to be replaced after physical checkup, Even the cost of ball is not costly but SOP for ball replacement to be added.