In an effort to improve the efficiency of CO2 in warm climates, German manufacturer BITZER presented the new EXPANDER subcooling unit for CO2 transcritical refrigeration systems at Chillventa. The firm argues that the unit can improve the efficiency of CO2 transcritical systems by over 20%.
“The EXPANDER is a new way to improve the energy efficiency and cooling capacity of new and existing CO2 transcritical refrigeration systems,” Oliver Javerschek, project manager at BITZER, told R744.com at Chillventa, an HVAC&R tradeshow held in Nuremberg on 16-18 October.
Functioning much like traditional external subcoolers, the EXPANDER comprises a control valve and a heat exchanger in addition to the expander-compressor unit at its heart.
The unit relaxes the primary mass flow, while the energy it generates compresses the subcooler mass flow and feed its back before the gas cooler.
“The principle relies on the fact that we have mechanical subcooling without requiring additional power input,” Javerschek said.
“The EXPANDER is a new way to improve the energy efficiency and cooling capacity of new and existing CO2 transcritical refrigeration systems.”Oliver Javerschek, BITZER
20% efficiency increase vs. standard booster systems
The EXPANDER is designed specifically for supermarket and logistics applications. At an ambient temperature of 32°C, BITZER claims that the new unit can increase a standard CO2 booster system’s cooling capacity at the design point by up to 20%.
“A single component retrofit can thus increase cooling capacity for transcritical CO2 systems,” the firm said.
BITZER has partnered with food retail giant ALDI Süd to test the first EXPANDER units in a supermarket setting. The German multinational discounter already uses BITZER reciprocating compressors in its CO2 transcritical refrigeration systems.