Electric motors have a massive part to play not only in the world of heating, ventilation and air conditioning (HVAC), but right across industry. So much so that these motors and the systems they drive are “the largest single-energy end use and account for more than 40% of global electricity consumption,” according to the International Energy Agency. And that figure is likely to rise sharply, with the number of motors in use forecast to double by 2040. Moreover, the global electric motor market size, valued at $106.3 billion in 2020, is expected to reach $207.3 billion by 2030, according to Allied Market Research.
While the energy crisis has eased back somewhat recently, they are still significantly higher than two years ago. “If the decrease in demand continues, wholesale prices should reduce,” states Abigail Ward, policy and communications officer at Energy Saving Trust. “However, while wholesale prices are low now, energy suppliers buy gas and electricity months in advance to make sure that prices and supply stay stable. This means costs are more fixed and any reduction in wholesale costs isn’t immediately passed on to consumers. Recent reports show prices for later in 2023 are now higher than the current cost of gas. This means that prices could be high next winter, too.”
The need for more efficient motors, therefore, is all too clear, if power bills – and levels of emissions – are to be substantially reduced. According to Daniel Eberli, head of product portfolio, IEC LV Motors, ABB, its motors have been focused on delivering that step-change for the past decade, culminating most recently in the IE5 synchronous reluctance motor (SynRM) with variable speed drive (VSD). “Awareness of how rising energy costs have been impacting businesses has greatly increased of late and brought about a big change in the mindset of customers.”
In the past, manufacturers might have been more focused on their main costs – namely input and output – with energy costs not necessarily getting the same level of focus. The energy crisis that has been felt right across Europe has altered that mindset, he points out. “Also, the reality now is that, whichever way prices may go, HVAC customers are already looking to invest in high-efficiency motors, such as the IE5 SynRM.”
One incentive is that, previously, such customers were seeing a 11-month payback of their investments. “That was rapid in itself, but today, at current prices, the return on investment can be as low as four months, depending on the application and prevailing electricity prices.”
He also points to how the purchase cost of a motor is only around 2% of its lifetime cost. “This makes replacement of a motor often the best way forward for a HVAC business to cut its energy bill through reduced losses.
“The SynRM motor is always working in tandem with the VSD to ensure that the speed of the motor is matched by what is required by the application, which again means lower energy costs.” With motors generally running for long hours every day, energy efficiencies are multiplied and consumption minimised, he adds.
“Our synchronous reluctance motors have been installed and running for the past 10 years, so the technology is proven. SynRM motors are also a direct replacement – same size, same fit – for a customer’s existing induction motors, which may also have incurred some degradation of materials and bearings over time.”
Induction motors have a ‘squirrel cage’ rotor, with currents induced in the bars, ABB points out, where the end rings form a short circuit, allowing heavy currents to flow, totalling up to 40% of the motor’s overall losses. “SynRM motors have no squirrel cage, no currents in the rotor, hence no rotor losses.” Adds Eberli: “Nor do those motors contain magnets or rare earth metals, such as permanent magnets, which are an environmental concern when it comes to how they are being mined.”
With climate change such a critical factor, he argues that there really is no other choice but to embrace the new generation of synchronous reluctance motors with variable speed drives. “By using high-efficiency solutions, ultimately we can decrease energy usage globally by up to 10%.”
ENERGY, MONEY & EMISSIONS CUTS
Another supplier in the HVAC field is Future Motors, exclusive supplier of the Turntide Smart Motor System in the UK. “The important thing about this system,” says Andy Sumner, Future Motors’ commercial director “is that it saves a great deal of energy, money and carbon emissions for HVAC operators, while the means to implement them is achieved through very straightforward means.”
The Turntide Smart Motor System delivers these efficiencies, he explains, through its switched reluctance design. This software-driven solution includes the Turntide Smart Motor and Turntide Motor Controller, complete with networking and connection capabilities to Turntide Cloud.
The Turntide V0 series of IEC motors are, he states, “suitable for a range of new and retrofit HVAC, refrigeration and pumping applications”, in both fixed and variable speed. The Turntide Motor Controller, for its part, controls all operations of the Turntide Smart Motor. “Its internal program assures that the motor is operating at the highest efficiency, at any speed, in any application,” adds Sumner. “It does this by monitoring the internal sensors and feedback from the smart motor, and adjusting control signals for optimisation.”
All of which, states Sumner, is exposing the limitations of the induction motor. “Induction motors have been around for a hundred years and have reached the point where they have reached their maximum level of efficiency, which is incompatible with what is required for today’s dynamic management of a building. As induction motors speed up or slow down, their efficiency levels fall by up to 75%, whereas smart solutions, such as ours, run at 90% efficiency.”
TIME OF TRANSITION
He acknowledges that the induction motor still has some way to run, as it enjoys a strong manufacturing base and is relatively inexpensive to produce. “However, as new technologies become more pervasive, demand will start to dwindle and the shift away will then accelerate. I would expect it [the induction motor] to gradually fade away and disappear as smart motors become more established. This transition will also be driven by energy pricing and the need to reduce carbon usage.”
One dark cloud hovering over the industry of late has been the global shortfall of microelectronics. How is his company coping with that threat? “Something that helped protect our business from the worst aspects is that we anticipated this might be an issue and made the decision a while ago to buy in a really high level of stock. This has given us an important buffer – to the degree that we are fairly confident we are going to be able to meet demand for the next year.”
But what then? “In the meantime, I would expect that, with energy price inflation pushing up demand, that will bring a corresponding increase in the availability of these components, especially as China is now coming out of COVID restrictions and is a major supplier.” Whatever transpires, he sees the switched reluctance motor as a technology whose time has come.
BOX: FREE-RUNNING FANS
For good reason, free-running or hybrid radial fans have largely replaced fans with scroll housings in air-conditioning applications, comments Italian-German supplier Nicotra Gebhart. “Even though the latter have some positive physical characteristics, free-running fans take up less space, and drive losses due to belts, bearings or couplings are not an issue. Planners are particularly focused on lower pressures. In addition, the European Ecodesign directive prescribes variable-speed drives. This favours direct-drive solutions.”
In terms of physics, free-running impellers can only achieve a pressure increase or energy conversion in two ways: a swirl added to the flow and a maximum delay in the relative flow in the impeller’s blade channel. “A swirl in the flow at the exit from the impeller is unavoidable and necessary for energy conversion. However, this swirl also represents a loss in air-conditioning applications. As a result, fan concepts of this kind can achieve maximum aerodynamic system efficiencies of around 70%.”
With the COPRA product, it has been possible to make the internal-rotor motor so short that it does not obstruct the impeller’s airflow, “as is the case in conventional fan solutions,” the company states. This is said to create ideal conditions for particularly economical operation, even in tight installation spaces. “At the same time, the new motor/impeller concept ensures very low installation losses. So there are hardly any unexpected, disadvantageous interactions between fan and application.”