HVAC solutions are getting smarter and more efficient every year. These advances are driven by both customer demands and new regulations. Two components that are helping HVAC manufacturers meet these demands and differentiate their offerings are, variable speed drives (VSDs) and magnetic bearings on the drive trains of compressors.
Businesses and governments are becoming increasingly aware that the energy costs that their HVAC systems incur can equate to up to 40% of a building’s total energy costs, and that this equipment has considerable bearing on the environment. With energy costs rising and stricter environmental legislation coming to the fore, users are demanding higher system efficiencies, lower operating costs and the use of more eco-friendly refrigerants. Users are also looking more closely at the total lifecycle costs that will be incurred.
HVAC plant requires significant investment but generally has a long lifespan – anything from 15 to 20 years. To maximise their investments, users are demanding increased reliability and longevity of HVAC equipment and are very interested in ensuring lifecycle costs are kept low.
A chiller that incorporates VSDs can lower the chiller’s annual energy use by 30%. How does it work? A VSD, as its name implies, allows a chiller to run at lower speeds under part-load conditions, thereby yielding a higher efficiency and lowering energy consumption.
But savings are not automatic. The trick is to understand how your VSD can save money and apply it correctly within a system.
With higher demands for energy saving, VSDs are finding their way into more HVAC solutions, ranging from rooftop packages to central chiller plants and other devices. And they are continually advancing – during 2019 and 2020, VSD manufacturers will invariably focus more on flexible connectivity, easy interactive set up, easier interrogation in the event of a failure, and enhance optimised control.
Magnetic bearing trends
To meet the need for superior reliability and performance, HVAC leaders are incorporating magnetic bearings into chiller drives. With fewer moving parts, no contact, and therefore no requirement for lubricant, there is less wear on mechanical parts and maintenance cost and effort is lower. This can help increase the lifespan of the equipment, with the elimination of oil, mechanical seals, wear surfaces and gears contributing to increased component and system reliability.
The key component of these contact free bearings is the magnetic bearing controller. The OptiView controller and panel that comes with the York VSD magnetic bearing chillers uses multiple sensors to monitor the positioning of the bearings and the rotating assembly, with the controller constantly optimising the field to maintain the rotational position.
“In terms of magnetic bearing trends, we expect manufacturers to work on reducing costs as demand for these advanced solutions rise,” Hattingh adds.
Johnson Controls’ YORK YZ
With next-gen refrigerant, a built-in VSD and magnetic bearings, the new YORK YZ chiller is using advanced technology to deliver best available energy efficiency ratings. “It’s hard to fault the new Johnson Controls’ YORK YZ Magnetic Bearing Centrifugal Chiller. Released globally in September 2018 and now available in South Africa, it brings together ground-breaking YORK innovations refined over decades of real-world use to deliver the world’s first chiller fully optimised to use the next-generation low-global warming potential (GWP) refrigerant, the R-1233zd(E). The YORK YZ is rated as ‘the world’s most efficient chiller’ – a claim that cannot be made without proof,” Hattingh reveals.
Johnson Controls has pulled out all the stops to achieve this accolade. The York YZ, which provides cooling capacities of between 800 kW and 3.5 MW, is truly the most advanced and energy efficient solution in its class. The technology delivers extraordinary reliability and radically simplified maintenance, which translates into massive cost savings.
“I believe it will achieve a strong uptake among organisations that are focused on energy efficiency and greener refrigerants, driving down operating and lifetime costs, and maximising their investments,” he says.
Johnson Controls used a holistic approach to the system’s design and engineering, optimising every component around the low GWP refrigerant for ultimate performance. The chiller uses an integral, variable speed drive and advanced magnetic bearing technology that features a single moving assembly suspended in a magnetic field that does not require lubrication. This technology requires significantly fewer moving parts than traditional oil- or refrigerant-lubricated drivelines.
“The result is enhanced reliability, reduced maintenance and improved efficiency,” notes Hattingh. “And if you want to quantify that, compared to traditional fixed-speed oil-bearing chillers, the YZ delivers up to 35% annual energy savings. That’s a huge saving when you consider that the initial cost of the chiller is only a small fraction of the life cycle operating energy cost.”
The energy savings and lower operating costs the YZ chiller delivers are achieved by taking advantage of the off-design conditions where chillers operate 99% of the time. The YZ operates with entering condenser water temperature as low as 4.5 °C, providing enhanced performance in every operating condition and the widest operating envelope in the industry.
The chiller can also operate with condenser temperatures below the evaporator temperatures, eliminating the need for a water-side economiser, which simplifies the system, requires less mechanical room space and saves money on components, piping, controls and maintenance.
It’s not all about the tech
“It is important for companies to work towards a sustainable future and this should reflect in their chiller designs, ie, the equipment they choose, the consumables and refrigerants they use and the way they control their systems to optimise their operations spend. We only have one planet and companies need to be responsible when selecting and implementing new technology,”Hattingh believes.