Variable Speed Compressors Provide Significant Environmental and Financial Advantages Compared to Fixed Speed Compressors
By John Prall, Technical support Engineer
Reducing environmental impact is an important part of doing business today. Companies are no longer waiting for government – or industry – mandated regulations to lead the way in becoming more energy efficient and environmentally responsible. Yet, positively impacting the environment shouldn’t negatively impact your bottom line. Doing good needs to also be good for business.
That’s why the light commercial refrigeration market has started to switch to variable speed compressors (VCCs) using R-290 natural refrigerant. VCCs are a much more environmentally responsible option that also provides significant savings and smart business benefits compared to traditional on-off compressors.
There’s no denying the substantial upfront financial investment required to phase out and upgrade legacy cooling systems with these more efficient solutions, so it’s important to carefully weigh the differences. To see the significant return of investment (ROI) and other advantages your business can realize from VCCs, there are five areas of comparison that matter most.
Variable vs. Fixed Speed
A traditional fixed speed (on-off) compressor operates at a constant speed, continuously switching on and off to meet your equipment’s energy demand. This operational pattern requires abrupt power loads when starting and can lead to wasted energy after the target temperature is reached but the motor has not yet turned off.
VCCs are able to recover from door openings much faster, reducing the time the system spends removing the heat infiltration. During stabilized conditions, the compressor can operate at a lower, more efficient speed to match the equipment’s energy demand, helping you to more quickly realize significant ROI.
In fact, the switch from on-off compressors to VCCs in vertical freezer equipment can pay for itself in just six months. That’s because VCCs reach target temperature up to 70% faster, saving up to 33% energy consumption (sure it also depends on proper VCC compressor model selection).
Soft vs. Hard Start
VCCs “soft start,” meaning the compressor starts at a lower speed, ramps up to full speed within a few minutes and continually adjusts current to provide needed power depending on the system’s conditions.
This slower ramp up time compared to the “hard start” of on-off compressors dramatically reduces the starting current of the motor. This decreases stress on the motor, helping to extend the machine’s lifespan and ensure the cooling aspects of your business stay up and running.
The use of an inverter eliminates the need for the start relays, start capacitors and run capacitors required in on-off compressors. Fewer parts that can fail from everyday wear and tear also helps to provide a better long-term return on your equipment investment. Additionally, having fewer parts and decreased equipment stress levels leads to significant operating noise reduction.
Hydrocarbon (Natural) vs. Hydrofluorocarbon Refrigerant
The global warming potential of refrigerant gas drops from 3922 all the way down to 3 when using a natural option, like R-290, rather than a hydrofluorocarbon (HFC) refrigerant, like R-404A. Additionally, the total refrigerant charge drops from 350g to less than 150g, significantly reducing your direct carbon footprint.
What’s more, switching to a natural refrigerant can reduce energy consumption by up to 20%. Using that natural refrigerant in a VCC, rather than in an on-off compressor, can reduce energy consumption by another 20%, providing an ROI that can pay for itself in as little as six months. It’s a win-win combination for sustainability and profitability.
Ambient vs. Product Temperature
Compared to on-off compressors, VCCs recover from door openings much faster. Operating at variable speeds enables these compressors to more easily and quickly regulate the delta between product and ambient temperatures. The higher the temperature delta, such as in freezers and other equipment operating at lower temperatures, the greater the ROI a VCC provides.
In fact, VCCs have shown a 20% average pulldown reduction, enabling the compressor to run at lower, energy-saving speeds. This ability to better regulate temperature also makes VCCs a highly effective solution for food preservation and medical applications, where products are very sensitive to temperature oscillations.
Compact vs. Conventional Layout
VCCs are not only energy efficient, they are space efficient, too. A VCC with natural refrigerant generates the same cooling capacity of a conventional on-off compressor using HFC gas, but in a much more compact equipment layout.
By freeing up more merchandising space in commercial cabinets without changing any external dimensions, manufacturers can more creatively design equipment and provide more flexible layout options to stores.
The Advantages of VCCs are Obvious
After comparing the benefits of VCCs with natural refrigerant vs. on-off compressors, it’s easy to see why so many businesses are adopting this more efficient and reliable technology. It helps you to significantly reduce the environmental impact of your business while realizing energy savings that positively impact your bottom line.
Major refrigeration brands, like Embraco, a portfolio brand of Nidec Global Appliance, now offer a wide range of VCC and natural refrigerant options. These trusted suppliers can help you access all the environmental — and, just as importantly, financial — benefits of making the switch to a more cost-effective way to increase equipment lifespan, company sustainability and ROI.
John Prall serves as a Technical Support Engineer at Nidec Global Appliance North America. His responsibilities include providing engineering technical support about Embraco brand’s portfolio for commercial and aftermarket customers, including assisting customers in selection and application of hermetic compressors. He also trains customers on compressor technology and market trends through customer visits, trade show presentations and webinar activities.
Prall has more than 15 years of experience in the commercial refrigeration industry. Prior to his role at Nidec Global Appliance, he held several roles ranging from engineering to product management at a leading food retail equipment manufacturer. Prall holds a BS (bachelor of science) in Mechanical Engineering from the Rochester Institute of Technology in Rochester, New York.
About Nidec Global Appliance
With over 15,000 employees across 9 countries, Nidec Global Appliance manufactures and commercializes components for home and commercial applications, including cooling solutions, motors for washing machines, dryers and dishwashers, as well as components for heating, ventilation, air-conditioning and refrigeration systems (HVAC&R). Its focus is to deliver a complete and innovative portfolio with high standards of quality, reliability, competitiveness and energy efficiency. The division is part of Nidec Corporation, a global leader in motors and components, with headquarters in Japan. Further information: www.nidec.com