Thursday, December 13, 2012

Retrofit Away From R-22

The Air Conditioning, Heating & Refrigeration NEWS VOL.247 NO.14

December 3, 2012

a warehouse-type food store in California
A real-world example of a retrofit of an R-22 system with an HFC was a warehouse-type food store in California.
Two recent projects demonstrated successful retrofitting of HFC refrigerants into existing HCFC-22 systems. These projects, which were highlighted by Arkema, detail the processes with regard to HFC-427A in refrigeration and air conditioning applications.
In one project, a warehouse-type food store in California underwent the retrofit. According to the case history, Tim Grant, HVACR engineering supervisor for Fiesta Foods, was looking for an HFC with easy retrofit, good performance, and low GWP for 10 food warehouse stores.
The retrofit was first tested at one store. The HFC was retrofitted into systems operating at -25˚F, 15˚, and 25˚ with a total of 12 compressors and racks divided among three suction groups with two receivers. The compressors used alkyl benzene (AB) oil and that oil remained in the system following the retrofit.
The retrofit was done by store mechanical refrigeration technicians. No components were changed during the retrofit, except for the filter driers. Some minor settling adjustments were made to the TXV and controls to optimize the system.
According to those involved in the project, the refrigeration racks reached their set temperatures quickly after the retrofit thus avoiding downtime or food spoilage. Operating pressures were similar with the HFC as with R-22. In addition, compressor discharge temperatures were reduced after the retrofit and compressors were said to run cooler than before.

Air Conditioning
On the air conditioning side, R-427A was used to retrofit the air conditioning unit for Solar Supply’s warehouse office in Lake Charles, La. The company is an HVACR wholesaler. One reason for the project was for the company to have firsthand experience with the refrigerant in a retrofit application.
According to the case history, Brent Miller’s Heating and A/C performed the retrofit with the refrigerant manufacturer’s technical service personnel on site for support.
The system consisted of a 3.5-ton heat pump, utilizing an orifice as the expansion device. The air handler was connected to the rooftop-mounted condensing unit with a 10-foot vertical riser.
Initial readings were taken in the morning to verify system performance with R-22 before the original refrigerant charge was recovered. The filter drier and the Schrader valve caps and cores were replaced. A deep vacuum was drawn before recharging with the HFC. Charge weight of the HFC was optimized and readings were taken to compare to R-22’s system performance.
According to the case history, the system operated as expected with no significant differences in system performance observed. Office temperatures were considered comfortable. Operating pressures of the HFC closely matched those of R-22 while the compressor ran at lower amps and discharge temperatures.
Publication date: 12/3/2012

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