Japanese OEM Daikin’s new propane (R290)-based LMSEY monoblock for walk-in cold rooms – which uses an FMF inverter compressor manufactured by Embraco – has been found to significantly reduce energy consumption compared to fixed-speed HFC units.

The Daikin system cut energy use by 20% compared to an R134a-based on-off unit of similar capacity in medium-temperature (MT) conditions, and by 41% compared to an R452A-based on-off unit of similar capacity in low-temperature (LT) conditions, according to a study conducted by the manufacturers.

The study found that R290 was more energy efficient than HFCs and that performance was further improved with the use of inverter, also known as variable-speed, compressor technology.

Results of the study were presented by Erik Venturi, Daikin’s Section Manager NPD Commercial Refrigeration, and Marino Bassi, Key Account Senior Advisor at Embraco (a brand of Nidec Global Appliance), during a refrigeration session at the ATMOsphere (ATMO) Europe Summit on natural refrigerants. The conference took place November 15–16 in Brussels and was organized by ATMOsphere, publisher of Hydrocarbons21.com.

“Entry-level on-off R290 design guarantees an improvement of efficiency if compared to HFC appliances,” said Venturi. “However, inverter compressor technology guarantees a remarkable improvement of efficiency if compared with on-off appliances.”

By reducing energy consumption, the study indicates that Daikin’s LMSEY refrigeration unit can also help to reduce greenhouse gas emission and the cost of ownership.

“Entry-level on-off R290 design guarantees an improvement of efficiency, if compared to HFC appliances. However, inverter compressor technology guarantees a remarkable improvement of efficiency if compared with on-off appliances.”

Erik Venturi, Daikin

Improved energy efficiency

According to the tests, Daikin’s LMSEY1 monoblock unit resulted in a better energy efficiency ratio (EER) than HFC- and propane-based fixed-speed alternatives in both MT and LT conditions.

The LMSEY1, which contains one circuit and a maximum of 150g (0.3lbs) of R290, offers 1.28kW (0.4TR) in cooling capacity for MT applications at 0°C (32°F) and 0.75kW (0.2TR) in capacity for LT applications at -20°C (-4°F), at an ambient temperature of 32°C (89.6°F).

In MT conditions, transitioning from an on-off R134a unit to a similar R290-based model resulted in a 7% improvement in the EER and a 6.8% reduction in energy consumption. An additional 19% improvement in EER and 13.6% reduction in energy use was recorded with the LMSEY1 unit.

In LT condition, the EER was improved by 53% and energy consumption reduced by 34.8% by using an on-off R290 unit rather than a similar R452A-based model. An additional 15% improvement in EER and 5.8% reduction in energy consumption was recorded with the LMSEY1 unit.

Reduced emissions and costs

Through improved energy efficiency, Daikin’s LMSEY1 also resulted in a lower total equivalent warming impact (TEWI) – which factors in both direct emissions from the refrigerants and indirect emissions from energy use – and annual cost of ownership.

In MT conditions, the TEWI and cost of ownership were reduced by around 8% and 7%, respectively, by transitioning from fixed-speed R134a to similar R290 technology. An additional 12% reduction in TEWI and 13% reduction in cost of ownership was seen with the LMSEY1.

In LT conditions, both the TEWI and cost of ownership were reduced by around 35% with a fixed-speed R290 unit, compared to an alternative using R452A. An additional 6% reduction in the TEWI and cost of ownership was seen with the LMSEY1 unit.

According to Venturi, transitioning to a more energy-efficient monoblock could have a significant impact in terms of global CO2 emissions reductions, considering how many units there are in the market.

Easy HFC replacement

In addition to the LMSEY1, the range also includes the LMSEY2, which has two circuits and offers larger cooling capacity. For MT applications, the larger unit provides 2.45kW (0.7TR) in cooling capacity. For LT applications, it offers 1.41kW (0.4TR) in capacity.

To increase capacity further, up to five units can be connected, explained Venturi.

As detailed in the presentation, Daikin’s new refrigeration units have the same dimensions as common HFC-based units, which allow for easy replacement of existing cold room appliances.

“Our case study also shows that the new solution allows a quick and low-effort refurbishment of existing cold rooms to reduce cost and environmental impact,” said Venturi.

The manufacturer showcased the unit at the Chillventa tradeshow in Germany in October and at Gulfood Manufacturing 2022 in Dubai last month.

According to Venturi, the product will be available in the coming months in Europe and North America. He added that the manufacturer is also considering developing it for other markets, which will be relatively easy due to the frequency range offered by the Embraco compressor.

Inverter technology

As indicated by the tests, inverter compressors are a valuable technology for reducing energy consumption.

In addition to energy efficiency, the FMF compressor offers low noise and vibration and can quickly recover from temperature changes, helping to ensure produce freshness, Embraco said.

“An additional benefit of variable speed technology is keeping food fresh for longer by maintaining better temperature stability inside the cold rooms,” said Bassi. “This technology overcomes temperature variations caused by door-openings much faster than the standard on-off compressor models, thus improving food preservation and potentially avoiding product loss”.

According to Embraco, the compressor includes its Smart Drop-In control logic software, which “simplifies the setting of parameters and the matching of the compressor with the system, easing the adoption of variable-speed technology.”