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FUTURE OF VSDs AND VFDs Driving the way in sustainable refrigeration

Mar 15, 2022

The refrigeration industry, which is perhaps one of the most outstanding technological innovations, needs to urgently address the challenges of its industry harming the global ecology and economy. Variable speed drives (VSDs) and variable frequency drives (VFDs) are sure shot ways to optimise the energy consumption of the conditioned atmosphere and refrigeration process. The article details the growing appeal for VSDs and VFDs and how upgrading to these can significantly benefit energy and cost.

While technologies are transforming the way we work, live, move, as well as power and produce, there’s also an urgent need to address the climate and environmental challenges that are harming our ecology and economy. Refrigeration is arguably one of the greatest technological innovations that have modernised societies everywhere by improving the overall standard of living. The global food and beverage (F&B) industry, one of the largest energy consumers, would be practically obsolete without refrigerators.

The food & beverage industry is essential in sustaining the world’s population. However, it is highly energy-intensive, estimated to consume 30% of global energy and 20% of greenhouse gas emissions. Adding to it, with the population forecast to reach nine billion by 2050, food demand around the world is likely to grow by 50% in that time.

The refrigeration and cooling sector is responsible for ensuring that products are stored and transported at appropriate temperatures, helping prevent any wastage within the industry. Refrigeration is required at all production steps, from chilling and freezing in a factory to cold storage in a retail display. A food plant can account for more than half of all electricity usage. Given the strong focus on climate change today, businesses rethink their priorities. Alongside profit, companies increasingly have to consider the environmental costs of doing business. This brings us to the question: how can we achieve energy-efficient refrigeration?

The potential for energy savings in refrigeration systems

Refrigeration systems can consume up to 70% of the total electrical energy used in a food & beverage plant. Yet, even today, these systems have one of the most overlooked opportunities for energy saving. Realising these potential savings can cut costs significantly, boost profitability and reduce CO₂ emissions. Variable speed drives (VSDs; also referred to as variable frequency drives – VFDs) are an efficient tool to optimise the energy consumption of conditioned atmosphere and refrigeration processes.

Since cold storage and refrigeration plants typically run 24/7, most refrigeration applications are potential VSD candidates. Any refrigeration system with a wide load variation during its operating hours or a heat load less than the peak load can benefit from a VSD.

Sustainable refrigeration with VSD

Although the food & beverage industry relies on many energy-intensive processes, there are many opportunities to optimise energy efficiency. Technologies and solutions are available now, which can significantly reduce energy consumption. Technology partners like ABB can also provide expert advice and solutions to help businesses optimise their operations. Many food & beverage industry applications are usually run at partial loads, like fans, pumps, compressors, and conveyor belts. However, these traditionally use mechanical control methods like valves, brakes and throttles to control their speed. In this system, the motor is doing more work than necessary, and energy is being lost through the mechanical speed control. VSDs offer a more efficient way of running applications at partial load because they can directly control an electric motor’s speed and torque. Since cooling units normally run non-stop, ensuring that only the required amount of energy is used can significantly reduce costs and efficiency. Adding a variable speed drive to a fan, pump or compressor can reduce energy use by 25%. VSDs can be retrofitted to many existing systems. The speed of the electric motor is then directly controlled by the VSD, with the mechanical controls generally left fully open.

Because cooling systems employ motors and drives, it is possible to manage their temperature while preventing energy wastage with the help of the latest energy-efficient technologies. Traditionally, industrial chillers have operated with stop-start condensers and evaporator fans, sometimes enhanced with the two-speed operation. Screw and reciprocating compressors, air or water-cooled condensers and DX or flooded evaporators are widely used throughout industrial refrigeration applications from cold rooms to blast freezing, where refrigerant temperatures can reach -45°C. The systems are generally larger than those in the retail sector, often in excess of 500 kW and utilising several compressors to obtain high capacity. While these systems have operated well for decades, a greater awareness of operational costs, particularly energy consumption and the need to use more environment-friendly refrigeration systems, has led to the use of VSDs and more efficient motors like ABB’s SynRM being introduced. Today, VSDs have successfully replaced many traditional techniques for controlling the cold storage systems used in the food & beverage sector. Thanks to the precise control offered, they play an important role in ensuring safe and sustainable refrigeration.

Benefits beyond energy savings

Aside from the proven energy savings benefits, VSDs also offer additional benefits. They can increase the lifetime of the equipment. Instead of running at full speed continually, the lower speed reduces stresses on the equipment, extends service intervals and cuts maintenance costs. VSDs can also be retrofitted to many existing systems. They can contribute to more consistent operations by helping to tackle harmonics, a form of electrical pollution that can cause interference to sensitive electrical equipment, resulting in unplanned plant shutdowns and loss of productivity.

Digital monitoring enhances safety & efficiency

The emergence of the Internet of Things has sparked renewed interest in machine condition monitoring systems, and some companies across the world are already utilising it for optimal equipment monitoring. ABB Ability™, condition monitoring for drives, provides fact-based insight into drives via KPIs and signal data, allowing the companies to keep their operations running smoothly.

Digital monitoring of drives enables companies to detect abnormalities before they become issues. Variable speed drives can be connected via a gateway. Companies can access the monitoring portal using the condition monitoring solutions, where all the service data is collected. The drive performance can be monitored by accessing live data, including availability, condition, operating parameters and fault events. As a result, maintenance can be planned according to actual needs rather than fixed schedules or unexpected breakdowns. It also offers the possibility of taking proactive decisions built on real-time information on drive events.

Modernise to more efficient motors

In addition to adding VSDs to improve the efficiency of existing applications, upgrading motors to more efficient models can also improve the overall efficiency of cooling applications. Currently, in India, many motors in use in the food & beverage industry have IE2 or even lower efficiency. However, motors with much better efficiency are available. For example, induction motors are available with up to IE4 efficiency and synchronous reluctance motors, like ABB’s SynRM motors, are available with IE5 efficiency. Since each IE class delivers 20% lower losses, upgrading offers the potential for significant energy and cost savings.

Increased awareness of energy consumption and operational costs is leading to a broader appeal of VSDs and high-efficiency motors. Industries are moving towards more sustainable forms of cooling as we assess the impact of refrigeration on climate change and recognise that it’s our responsibility to encourage solutions and products that are eco-friendly. Keeping our drinks cold in the future is possible through the continued adoption of newer, more energy-efficient technologies in the industry.

Courtesy: ABB India

Image Gallery

  • VSDs offer a more efficient way of running applications at partial load because they can directly control an electric motor’s speed and torque

  • Companies can access the monitoring portal using the condition monitoring solutions, where all the service data is collected

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