Compressors Become More Efficient
THE GOAL IS ENERGY EFFICIENCYFor compressor manufacturers, variable-speed units are a way to achieve better energy efficiency.
“In order to reduce energy consumption, there is a growing trend to apply variable-speed and variable-capacity control technologies to compressors,” said Keith Gifford, director of global marketing, Tecumseh Products Co. “Variable-speed and variable-capacity technologies save energy by running the compressor at slower speeds and using intelligent devices to closely match system operation with actual demand,” he continued.
Greg Johnson, global marketing manager, Danfoss, agrees that the place that variable-capacity compressors hold in the market is on the rise. “The most significant change [in compressors] will be the shift to variable-capacity technologies in residential and commercial applications in the near future as legislation and regulations through national standards, as well as local building codes, continue to increase the minimum efficiency levels. The proposed residential regional standards will allow OEMs and compressor manufacturers to optimize designs for new efficiency levels and climate. Smart grid and demand response communication is a rapidly growing opportunity as utilities manage their grid during peak load periods.”
OTHER COMPRESSOR TRENDSA second change of late in compressors is the types of refrigerant used in them, due to various governmental rules. Johnson said, “Designs are also being optimized for HFC refrigerants, which have completely replaced HCFC refrigerants.” Further, he stated “As the industry adjusts to new compressor technologies, it must also adapt to refrigerant changes. The current HFC refrigerants will be phased down under proposals like the Waxman-Markey bill and the Montreal Protocol Amendment. It is obvious that a new refrigerant will be required as well as new, optimized compressor designs.”
Gifford also sees refrigerants affecting compressor designs. “Compressors are also being optimized for use with natural refrigerants such as R-290 (propane), R-600a (isobutene), and R-744 (carbon dioxide),” he said.
According to Gifford, the latest in compressor trends “is to make them smaller, lighter, and more efficient without sacrificing reliability.” He also sees linear compressors being used more in refrigerators and freezers. The reason for this, according to Gifford, is “the main advantage with linear compressors is their low energy consumption.”
Johnson sees current compressor trends as including “modulation through use of multiple compressors, mechanical or electronic capacity control, especially toward variable speed” as having “a significant impact on the HVAC industry.”
Another development in compressors he’s noticed is the use of electronics and “compressors optimized for heating conditions to support the North regional regulations.”
Variable-speed technologies, use of non-HCFC refrigerants, and efficiency are characteristics that both Johnson and Gifford view as to the reasons why compressors of today are greener than they were five to 10 years ago.
“Compressor efficiencies over the last five to seven years have increased at an average rate of 1-1 ½ percent per year,” remarked Gifford. He also mentioned the fact that compressors now are quieter than they used to be, so are greener for that reason as well.
Another advancement in compressor design that makes them more environmentally friendly is that, said Johnson, “Some designs have eliminated the need for oil inside the compressor through the use of magnetic bearings, such as the Danfoss Turbocor technology.”
Sidebar: Maintenance TipsJohnson advises contractors to perform regular system maintenance so that the “systems operate as efficiently as possible, and reduce energy consumption and greenhouse gas emissions at the point of production.”
Parts of this system maintenance, said Johnson, includes:
• Cleaning coils,
• Replacing dirty filters,
• Maintaining proper system charge,
• Adding or replacing insulation, and
• Eliminating duct losses through leakage.
Gifford’s list for maintenance to keep a compressor running efficiently and prolonging its life is:
• Keep the refrigeration system clean and dry. “There’s nothing that kills a compressor quicker than moisture and/or contaminants in the system.”
• Avoid compressor overheating by properly applying refrigerant flow devices and operating/safety controls.
• Don’t operate the compressor outside of its design window.
• Follow the compressor manufacturer’s recommendations on piping and other system-related requirements that affect compressor oil return.
Publication date: 03/29/2010