ENERGY SAVING EQUIPMENT


Operating refrigeration plant needn’t cost the earth


With energy prices rocketing, Kevin Glass, managing director of Bitzer UK, highlights some high-tech, low-cost options to minimise cooling energy bills.


T


he recent sharp rise in energy costs is focussing minds on ways to improve efficiency and reduce the cost of operating refrigeration plant.


Government support for household energy bills has taken at least some of the sting out of price increases for homeowners. However, industrial and commercial users who's businesses depend on cooling are being hit hard. For some, particularly in food manufacture and


processing, cooling energy costs may account for more than 70% of their energy bill. It’s no wonder that controlling and reducing energy used in refrigeration is now a board- level issue. A key principle in any energy efficiency drive is ensuring


refrigeration equipment delivers the right amount of cooling to achieve its purpose. Over-refrigerating, or poor system optimisation, is money down the drain – and entirely avoidable. Variations in load and changing ambient conditions in our climate mean that most refrigeration systems are not required to operate at full capacity for long periods. In the vast majority of cases (data centres being a notable exception), part-load operation is likely to be the default condition. It is therefore vital to ensure systems are optimised at part load to ensure efficient operation and that running costs are kept as low as possible over the lifetime of equipment.


One way of doing this is by the use of current inverters. These sophisticated devices modify the electrical power input to the compressor motor in response to changes in load, slowing down or speeding up the compressor to match cooling output with demand. Implemented correctly, and properly matched to the system, inverters are very effective and significantly improve refrigeration efficiency and performance. The downside, of course, is that inverters can be


expensive and add a significant additional upfront cost when purchasing new equipment. If poorly implemented, they can also cause interference problems with nearby electrical equipment. Bitzer has developed a lower-cost alternative to cooling


16 January 2023 • www.acr-news.com


capacity control that does not depend on inverters, which is highly effective and without the high capital cost and potential interference issues. The CRII–Varistep control system enables proportional modulation of compressor output in response to changes in load and system conditions, giving stepless capacity adjustment from 50% up to 100% as standard, and 10% to 100% as an option. It uses a different approach to managing capacity


control, based on the principle of incrementally blocked suction. This uses hollow control pistons in combination with a bespoke algorithm to enable fine, fast-reacting control of compressor output. The design of the mechanical side of the control system is shown in the picture (top right).


The control algorithm – the system's brain – constantly monitors and adjusts output via mechanical actuators. The algorithm in each case is configured according to operating conditions and refrigerant, allowing very precise control and excellent system optimisation. The system is used on Bitzer's multi-award-winning Ecolite 2.0 condensing units, now available for use with A2L refrigerants, including ultra-low GWP R1234ze/yf, and lower GWP R455A and R454C. Designed for use in a wide range of applications, such as


cold rooms, petrol stations and convenience stores, Ecolite condensing units are available from 1.5 kW to 5 kW in low temperature versions and from 3.5 kW to 16 kW in medium temperature versions. Operating range spans -45°C up to 0°C, without requiring liquid injection. Despite its competitive price point, Ecolite delivers


excellent energy efficiency through a combination of this inverter-free capacity control, plus optimised heat exchangers and variable-speed fans. The ability to vary fan speed according to changes in load and ambient conditions delivers further significant energy savings. Ecolite uses the latest technology in this field, with integrated EC motors and fans encapsulated in an aerodynamically-optimised housing. The speed of the fan is constantly adjusted, so it maintains desired head pressure for the required duty.


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