A Coles Supermarket in Victoria has trialled new leak detection technology that has proven to be far more effective than traditional testing methods.
The trial was undertaken at a new low carbon store in Coburg, Victoria that could provide a template for other new stores.
The store boasts two transcritical booster R744 racks running the low and medium temperature refrigeration and air conditioning.
The racks are part of a CBES design assembled with every feature to enhance coefficient of performance (COP) including parallel compression, heat recovery and chilled water built onto the system. The Liquorland store also relies on natural refrigerants with R1270 integral cabinets running on a chilled water loop.
This ambitious project highlights Coles’ desire to use low GWP fluids backed by high energy efficiency to limit both direct and indirect carbon emissions.
The R744 system will run in transcritical format for only 850 hours per annum based on average ambient temperatures and is expected to reach COPs of eight when running sub-critical.
A-Gas was given the opportunity to trial Trace-A-Gas at the Coburg store through its wholesale partner Airefrig, the market leaders in the distribution of the leak detection technology.
The trial took place in June 2015 with representatives from A-Gas, Airefrig, CBES and Melbourne Refrigeration.
While the work was managed by CBES project manager, Brian Toulson, it was carried out by subcontracting firm Melbourne Refrigeration.
The trial was carried out on the first R744 rack after the system had been leak checked with nitrogen to 10,000 kPa on the high side. All identified leaks had been remediated and the system was considered leak free.
Trace-A-Gas was introduced into the system to a pressure of 2500 kPa which is 2.5 times higher than the normal pressure used for leak testing. This was done bearing in mind the higher operating pressures of R744 in the system.
Trace-A-Gas is a mixture of nitrogen with a small quantity of hydrogen which being the smallest molecule in the world will escape readily through any leak path aiding detection and making the product far more accurate than traditional leak testing techniques.
The system was then thoroughly leak tested using an electronic leak tester. Both mechanical and brazed connections were tested on the rack and also downstairs on the shop floor in the cabinets and island freezers.
Contractors found the leak checking procedure for the rack was relatively quick and much cleaner than using bubble spray to coat all of the fittings. It also proved the accuracy of Trace-A-Gas by identifying 13 leaks.
On the rack, the main problem area was the headers which had small access points linked with flexible hoses.
There were seven leak points detected and these were later verified visually using bubble spray.
A leak was discovered on the oil solenoid and three leaks on the pressure relief manifold outside on the roof.
On the shop floor, Trace-A-Gas also identified a leak on a distributor in an island freezer and a leak at the top of a freezer cabinet.
These leaks were not detected previously by the OEM or a nitrogen test after being installed in the store but they were found easily with Trace-A-Gas.
The trial proved to be a real success and conclusively identified a number of leaks that had been missed using traditional leak detection techniques.
Although R744 is relatively cheap to replace, the real benefit for Coles is the energy efficiency gains the store will experience by not running short of gas.
It will also allow the system to operate at its full potential reaching the COPs it was designed to achieve.
For more information, email info.au@agas.com or admin@airefrig.com.au.