Energy Recovery Vallarta Supermarkets PX G1300 pressure exchanger
From left, at ATMO America 2023, KC Chen, Energy Recovery; Steven Goh, Vallarta Supermarkets; and Clark Andrews, M&M Carnot

ATMO America: Vallarta Supermarkets Sees 30% Reduction in CO2 Refrigeration Energy Usage with Energy Recovery’s Pressure Exchanger

The PX G1300 unit provides ‘“free”’ compression and requires little to no maintenance with only one moving part.

From data gathered on May 23, an independent assessor determined that a Vallarta Supermarkets store operating in Indio, California, saw a 30% reduction in its CO2 (R744) refrigeration system’s energy consumption with the use of Energy Recovery’s pressure exchanger PX G1300.

The installation and performance of the device were described by KC Chen, Vice President of CO2 at Energy Recovery, along with Steven Goh, Director of Energy Management and Sustainability for Vallarta Supermarkets, in an end-user presentation at the ATMOsphere America Summit 2023, held June 12–13 in Washington, D.C.

“We got pushback from management about using CO2 refrigeration because of its energy usage until Energy Recovery showed us that we can use CO2 and save energy at the same time,” said Goh.

Before the PX G1300 installation, the Indio store used an adiabatic gas cooler (GC) to support the CO2 refrigeration system during high ambient temperatures. High-pressure CO2 comes from the discharge side of the adiabatic GC and goes through an expansion valve to drop the pressure and the temperature before entering the evaporator.

“By replacing the expansion valve with the PX, we can now recover this energy, which is otherwise lost,” Chen said.

The high pressure coming from the adiabatic GC goes through the PX G1300, where the pressure exchange happens. The low-pressure CO2 coming from the evaporator into the pressure exchanger is compressed by this high pressure and then piped to the inlet side of the gas cooler, Chen explained, adding, “The PX compresses the CO2 without electricity or water, making it free compression.”

This means that with the PX G1300, the main compressors do not have to work as hard, reducing the number of compressors in the system from three to two. “This is how we save electricity – by recycling high-pressure energy,” said Chen.

The PX G1300 unit became operational in the Vallarta Supermarkets store on November 4, 2022. Chen compared the store’s energy usage data obtained before and after the installation.

On November 1, with an ambient temperature range from 60 to 90°F (15.6 to 32.2°C), the store’s power consumption often jumped to 50kWh, with the adiabatic GC automatically turning on before 10 am and running continuously until after 8 pm.

On November 4, it was slightly cooler, with an ambient temperature range from 55 to 85°F (12.8 to 29.4°C). However, during the time that the adiabatic GC automatically ran from around noon to 6 pm, but so did the PX, resulting in the power consumption “dropping from the high 50s kWh range to the 20s,” said Chen.

An independent third party collected data this past May using industrial standards. On May 23, the ambient temperature ranged from 95 to 105°F (35 to 40.6°C), causing the adiabatic cooler to run all day. The PX G1300 was turned off and back on every two and a half hours. The compressor and adiabatic GC power consumption without the PX was 45.06kWh, and with the PX, it was 31.85kWh, “showing a 30% difference in power consumption with the PX on,” Chen said.

“Because PX provides extra free compression even when there is a heat wave, your CO2 refrigeration system can keep going, making it future-proof,” Chen said.

“We can use CO2 to meet the regulations and our goals and still save energy,” added Goh.

The PX G1300 unit has also demonstrated a 30% energy savings at an Italian supermarket.

Additional advantages

With a “simple” installation, the PX could potentially eliminate “quite a few” components, including the adiabatic GC and a parallel compressor, and reduce the number of required main compressors, which saves capital investment, Chen said. (According to Goh, the adiabatic GC will remain in the Indio location due to zoning regulations.)

In addition, it is an “extremely reliable” device with only one moving part, requiring little to no maintenance, said Chen. “We’ve deployed about 30,000 PX units around the world without aftermarket sales,” he added, referring to Energy Recovery’s 25 year history with the device being used for desalination and wastewater treatment.

The device is designed for a 25-year service life, with its internal parts made from engineered ceramics. However, Chen said that most of the PXs installed 25 years ago are still running today.

Headquartered in San Leandro, California, Energy Recovery “turned an invention for desalination into a global business to accelerate environmental sustainability operations in multiple industries,” according to the company website. The company’s PX G1300 pressure exchanger was awarded Innovation of the Year 2023 at the ATMOsphere America Summit 2023 based on HVAC&R industry voting.

“We can use CO2 to meet the regulations and our goals and still save energy.”

Steven Goh, Energy Management and Sustainability Consultant for Vallarta Supermarkets

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