Fung Lea Food, an Australian importer and processor of seafood and poultry among other products, has opted for an ammonia-CO2 cascade system to provide the cooling at its combined chicken processing and cold storage facility in Prestons, New South Wales.
Fung Lea counts multiple, small HFC-based cold stores in Sydney, Melbourne and Brisbane among its HVAC&R inventory. So what motivated the adoption of natural refrigerants?
“The company was looking to consolidate operations into a single plant,” Mack Hajjar, projects engineer at Tri Tech Refrigeration Australia (TTRA), told Accelerate Australia & NZ.
TTRA designed, installed, commissioned and now maintains the new Fung Lea installation, which employs a cascade system encompassing a GEA Grasso Duo high-side ammonia compressor package; a booster CO2 compressor rack fitted with GEA Bock compressors; and Witt CO2 liquid pumps.
The proprietary TTRA system, commissioned in January 2019, delivers 90 kW of cold storage capacity at -20°C and 250 kW of medium-temperature capacity for three chillers at 2°C, a dock at 10°C, a chicken processing area at 8°C, a cool room at 0°C and a process room at 6°C.
“It operates on ammonia as the high-stage refrigeration solution and GEA Bock compressors operating on CO2 as the booster solution,” says Greg Clements, head of sales – compression, at GEA Refrigeration Australia Pty. Ltd.
GEA supplied the ammonia compressors, the CO2 compressors, the CO2 oil, the Witt CO2 liquid pumps, and 3D drawings and documentation for the system.
“Fung Lea wanted CO2 for perceived efficiency benefits,” Hajjar says. “We convinced them to use water-cooled ammonia for the high side of the cascade for improved energy efficiency, improved service life, and lower total cost of ownership.”
“We convinced Fung Lea to use water-cooled ammonia for the high side of the cascade for improved energy efficiency, improved service life, and lower total cost of ownership.”Mack Hajjar, Tri Tech Refrigeration Australia
Heat recovery circuit for oil and defrost cooling
Among the features that make the system particularly innovative, Hajjar cites a heat recovery circuit for oil cooling and defrost cooling, and the use of the GEA Grasso Duo compressor package in standby configuration.
The system overall, “is a cost-effective solution for intermediate-size plants that are too small for full-scale ammonia, and too large for Freon,” Hajjar argues.
“It’s an appropriate trade-off between efficiency and cost whilst remaining natural refrigerant-based. It eliminates ammonia from the field, can be scaled up or down, and is entirely appropriate for supermarket applications,” he asserts.
Using a CO2 rack with only minimal additional features helps to improve the cost effectiveness of the Fung Lea system still further.
With appropriate modifications, the system can generate hot water by virtue of its heat pump and heat recovery functions. It can also be containerised, reducing the footprint of the plant room.
Given that the system was only commissioned in January, a full set of operating performance data is still being acquired.
Yet based on observed operation and power draw, “we expect the energy consumption of the freezer to be approximately 40% that of a similar air-cooled conventional Freon-based installation,” Hajjer predicts.