With the shadow of the EU’s 2021 energy saving legislation looming over the UK’s refrigeration market the industry is being urged to proactively target compressor efficiency in order to fulfil its carbon reduction obligations.
Compressors are by far the largest energy consumer within a refrigeration system be it a chiller unit or a direct refrigeration system and the technology has been highlighted as an area that needs improving as part of Lot 31 of the European Commission’s Ecodesign Directive.
The refrigeration industry consequentially faces an enormous challenge over the coming years to reduce compressor power consumption without affecting productivity, according to temperature control equipment experts ICS Cool Energy.
“A compressor’s basic function will always expend a certain amount of energy and as the principles of vapour compression will remain the same it is the compressor technology which must change in order to achieve the greater target efficiencies outlined by the Ecodesign Directive,” comments technical manager Brent Hall.
Operating processes of larger compressors should serve as inspiration for the industry, according to ICS Cool Energy. One such example would be oil-free compressors such as the Turbocor range which use magnetic bearings to offer improved efficiency and reliability levels by reducing moving parts. However, such compressors are not suitable for all applications therefore a decision should be made as part of the system design stage, not afterwards.
“Ultimately one of the most accessible methods of improving energy efficiency in the refrigeration market is to use built-in optimised variable speed drives (VSD) which in essence the Turbocor does,” Brent continues.
“Many compressors are currently running on one fixed speed regardless of demand and generally achieve a co-efficient of performance (or energy efficiency rating) of 3kw of cooling to 1kw of power. However, applying part-load optimisation through a VSD to scroll and screw compressors could allow operators to achieve a ratio of 4.5-5kw of cooling to every 1kw of power: an improvement of circa 50-60%.
“On the whole it appears that the technology is not too far away as VSDs are currently available as optional extras on larger plant and both inverter-driven screw compressors and digital scroll compressors have been introduced to the market. However for the industry to realistically achieve the savings mandated by the EU such advances must become commonplace across all chiller equipment within the next 10 years if not sooner.”