Dorin: CO₂ compressors competing at larger capacities

With the EU’s F-Gas Regulation compelling food retailers to adopt alternatives to HFCs, Italian compressor manufacturer Dorin sees CO₂ becoming increasingly competitive with ammonia – another natural refrigerant – for larger capacity installations such as distribution centres. R744.com reports from EuroShop 2017.

“We’re convinced that we’re doing the right thing by investing so much resources into large compressors. With CO₂, the only issue is cost. But as volumes increase, prices will go down,” said Giacomo Pisano, technical sales manager at Dorin.

At Chillventa 2016, Dorin launched two new compressor series. In the CD400 range, its 4-cylinder CD5200M model features a displacement of 35.2 m³/h at 50 Hz.

The company launched three series in the CD500 range:

• CD6 500-40B, CD6 600-40M, CD6 700-40H: 6-cylinder compressors with a nominal power of 50-70hp, featuring a displacement of 39.8 m ³/h at 50 Hz.
• CD6 500-45B, CD6 700-45M, CD6 800-45H: 6-cylinder compressors with a nominal power of 50-80hp, featuring a displacement of 45.3 m ³/h at 50 Hz.
• CD6 500-53B, CD6 800-53M: 6-cylinder compressors with a nominal power of 50-80hp, featuring a displacement of 53.2 m³/h at 50 Hz.

“If you compare a transcritical system for a supermarket to a unit with an HFO or R134a chiller with a glycol circuit for the vending area, frankly I think that today the CO₂ system is already cheaper,” Pisano said.

“I don’t see large retailers allowing big HFO charges in direct expansion in the vending area, because they are still mildly flammable,” he said.

Pisano is confident that CO₂ can compete with ammonia for large warehouses and other light industrial applications. “Now that these larger capacity compressors are available and operational in the field, retailers want to go ahead with CO₂,” he said.

Indeed the Transgourmet Group – a European wholesale and cash & carry giant – is adopting CO₂ for all refrigeration, air conditioning and heating applications , not just in new and updated stores but also in its distribution centres. Does Pisano consider CO₂ to be a serious rival of ammonia?

“Yes, a lot. For capacities of up to 2MW, I believe CO₂ is the solution,” said Pisano. “Some retailers would like to move away from ammonia. Before the EU F-Gas Regulation, they could do large systems with HFCs, but now that makes no sense,” he argued.

“If you compare a transcritical system for a supermarket to a unit with an HFO or R134a chiller with a glycol circuit for the vending area, frankly I think that today the CO₂ system is already cheaper.”

Giacomo Pisano, Dorin

Pisano presented performance data from a supermarket in Beijing demonstrating how a straightforward CO₂ booster system with a flash gas bypass produced an efficiency gain of a 0.5% compared to ammonia.

Add parallel compression, and the efficiency gain hit nearly 10%. Adding innovations like ejectors and heat reclaim would improve the performance of a CO₂-based system compared to ammonia still further, he argued.