ACR Journal

April | May 2023 REFRIGERATION 18 Volume 9 No.3 The results of this adoption reduced refrigeration load significantly and allowed operation with higher evaporating temperatures to save energy. In addition, in one of the less obvious benefits to installing cabinet doors, Aldi was able to specify the use of parallel compression on the transcritical systems. Historically in the UK, parallel compression for transcritical CO 2 for refrigeration systems hasn’t offered an attractive return on investment, but Flash gas Management for a 60 kW MT Pack Total compressor displacement (m3/h) Nominal Full Load Current (A) Nominal CoP at design conditions Minimum Capacity (kW) Flash gas Bypass 31.5 76.7 1.59 20 Parallel Compression 24.3 65.4 1.8 10 now the case for parallel compression is different. For systems which adopt heat recovery – a larger proportion of time is spent in transcritical operation. Secondly, parallel compression allows for a significant reduction in compressor displacement. This has the welcome consequence of improving suction pressure control at low loads. For a given 60 kW system– the differences in system characteristics can be quite stark. 2022 Onwards Aldi continues to evaluate approaches to optimise total expenditure, with improvements to system efficiency and performance at the forefront of its considerations. In the last 15 years or more Aldi has gone through a notable transformation of the refrigeration technology and processes it uses. The results of this mean that it is well placed regarding sustainable practices now and into the future, while it continues to try and identify further improvements in sustainable refrigeration in a competitive marketplace. Table 2 Flash gas to Parallel Compression Comparison 0 0.1 0.2 0.3 0.4 0.5 0.6 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 kg CO2e / kWh UK National Grid Carbon Intensity by Fuel Type Electricity Natural Gas Graph 3 Trend of UK Carbon Intensity by Fuel Type (including Transmission and Distribution losses)