4.2 Variable-Speed Compressors Meet Efficiency Requirements

Variable-speed compressors for hydrocarbon cases were introduced in 2007. In the last few years, several compressor manufacturers have started expanding their variable-speed portfolios, adding hydrocarbon compressors for both small and larger applications.

In support of this trend, research and testing have found that variable-speed compressors can outperform conventional on-off systems in energy efficiency, temperature recovery time, noise output and operating temperature. Additional advantages of the variable-speed units include the ability to withstand network voltage fluctuations and reduced stress on a compressor’s mechanical and electrical parts.

According to compressor manufacturer Embraco, a brand of Nidec Global Appliance, the market share of variable-speed compressors in plug-in hydrocarbon appliances was 18% (the rest being fixed speed) in 2021 and will grow to 30% in 2025 and 50% in 2030.82

Variable-speed compressor adoption is inevitable, says Embraco, in order to meet upcoming efficiency requirements around the world.

Embraco has presented several case studies supporting the benefits of switching to R290 variable speed. For example, using an R134a system with an on/off compressor as a baseline, a 1,120L (39.6ft3) R290 beverage cooler was able to achieve a 35.9% reduction in energy consumption. When adding a variable-speed compressor and R 290, it achieved an even higher 53.4% energy reduction in comparison to the baseline.83

German manufacturer Secop has also found cabinet efficiency gains of 20–40% when switching a fixed-speed compressor to a variable. Variablespeed compressors previously made up 6%–7% of Secop’s commercial compressor sales, but this share is growing, driven mainly by energy-efficiency regulations.84 According to U.S. manufacturer Tecumseh, its propane-based variable-speed compressor meets the requirements of the U.S. Environmental Protection Agency’s (EPA) Energy Star “Emerging Technology” award.85

Global beverage producer Red Bull, by installing a variable-speed propane compressor in its refrigerated display cases in 2021, has reduced its energy consumption by 43% compared to its 2007 model and by 8% compared to its 2017 model.86

The cases, supplied by Italian OEM EPTA Refrigeration, employ a variable-speed compressor with “Smart Drop-In” technology from Embraco.

While there is a cost premium for variable-speed compressors – about double the cost of fixed speed – there can be a quick ROI for the end user (in as little as three months).

Making hydrocarbons even better

By improving the efficiency of display cases, variablespeed compressors make hydrocarbon-based units even more attractive and generate a better return on investment and total cost of ownership.