Exploring the Efficiency and Performance Benefits of Variable-Speed Compression

Improving the energy efficiency in refrigeration, air conditioning and heat pump equipment is a goal shared by HVACR industry stakeholders across residential and commercial sectors. Original equipment manufacturers (OEMs) are pursuing equipment design strategies to achieve comprehensive energy-efficiency improvements driven by environmental regulations and corporate sustainability initiatives. In a recent article for HVACR Business, I discussed how variable-speed compression is an enabling technology in the development of next-generation, energy-efficient HVACR systems.

Comfort cooling/heating and commercial refrigeration equipment are consistently among the highest consumers of electricity in households and retail buildings. To address this persistent challenge, OEMs are exploring innovative, eco-friendly, variable-speed compression technologies that offer energy-efficient alternatives to traditional fixed-speed compression. Rather than cycling on and off to meet varying cooling, heating or refrigeration loads, variable-speed compressors support variable-capacity modulation — enabling the compressor to precisely match its capacity to ever-changing load requirements.

A variable-capacity modulation compression strategy significantly lowers energy consumption by reducing compressor cycling and eliminating the energy surges that occur during compressor start-ups. In addition to these energy-efficiency gains, it delivers a variety of performance-related benefits:

• Enabling softer start-ups and transitions for less compressor strain and longer compressor life
• Providing faster temperature pull-downs
• Maintaining tighter suction pressures and precise setpoint temperatures
• Delivering consistently even air temperature and humidity control for improved human comfort
• Supporting sustainability initiatives and net zero targets with the use of lower-global warming potential (GWP) refrigerants

Variable-speed compression technology is based on the pairing of a scroll compressor and a variable frequency drive (VFD). VFDs are commonly used in HVACR applications to control the speed and efficiency of a variety of motor-driven system devices, such as: fans, pumps, and other equipment and components. When combined with scroll compressors that leverage brushless permanent magnet (BPM) motors, VFDs deliver smooth variable-capacity modulation and maximum energy efficiency.

Market trends favor the increased adoption of variable-speed compression

Historically, variable-speed compression solutions have been considered suitable for applications with the most challenging load requirements, such as those with precise cooling demand ranges or high heating-to-cooling ratios (e.g., cold climate heat pump [CCHP] applications). Today, variable-speed compression solutions are among the few available technological strategies capable of meeting next-generation, energy-efficiency requirements.

Current HVACR market trends, sustainability drivers, technological advancements and the declining costs of powered electronics are setting the stage for the wider adoption of variable-speed compression — while removing previously existing barriers to entry.

• Seamless integration of compressor and VFD
• Easier to install and deploy
• More affordable and accessible to a wider base

Existing and emerging applications for variable-speed compression

To date, commercial and residential comfort cooling markets have led the way in the adoption of variable-speed compression strategies. With increasing HVACR industry demands for sustainability and energy efficiency, variable-speed compression technology is being deployed in heat pump and commercial refrigeration equipment.

Residential HVAC and heat pumps — Variable-speed compression technology has already demonstrated its effectiveness in residential comfort cooling applications. Compared to standard fixed-speed compressors, variable-speed compressors deliver significant improvements in AC cooling efficiencies — . In residential heat pump applications, variable-speed compression technology

In addition, the integration of economized vapor injection (EVI) and scroll compression technology — which is already commonplace across Asia and Europe — represents the promise of improved energy efficiencies and high performance in residential CCHP applications. EVI-enabled scroll compression technology provides economized circuit sub-cooling, which increases system capacity and efficiency.

Commercial heat pumps — Variable-speed compression solutions offer an expanded capacity range and scalability to adapt to a much wider set of application requirements. Although these have already been deployed successfully in various global regions, they will soon be introduced in the U.S. to address more challenging CCHPs and high peak-load scenarios.

Commercial refrigeration equipment — As OEMs face stricter energy-efficiency regulations from the Department of Energy (DOE) — and seek competitive differentiation via an ENERGY STAR® certification — more are integrating variable-speed compression solutions into their design cycles. In addition, many OEMs are combining design cycles to include variable-speed solutions along with their transition to lower-GWP refrigerant options.

In self-contained coolers, freezers and display cases, variable-speed compression , while enabling precise load matching and increased reliability to help end users protect food quality and safety. For self-contained OEMs, one variable-speed compressor can cover a wider range of refrigeration capacities, reducing the need for multiple-compressor SKUs for varying equipment sizes. In remote condensing units, variable-speed compression also enables multiplexing configurations, where one condensing unit can support multiple fixtures.

Copeland is developing the next generation of compression technology

Copeland is committed to developing the next generation of compression solutions for all these existing and emerging applications. Through significant research and development (R&D) investments in compression technologies, collaborations with industry organizations and partnerships with leading OEMs, we’re helping to improve energy efficiencies in comfort cooling/heating, commercial refrigeration and emerging heat pump technologies.

Our recently launched Copeland variable-speed scroll compressor for commercial refrigeration was recognized at the International Air-Conditioning, Heating, Refrigeration Exposition (AHR Expo) as the 2023 Innovation Award winner.

For more information on Copeland HVACR technologies, please visit our website.