Improved indirect measuring methods for assessing the energy efficiency of a low temperature refrigerating system

Three indirect measuring methods for evaluating the energy efficiency of refrigerating systems are mentioned in specification VDMA 24247-7 (2021) - refrigerating plant model, compressor model and valve model. In a contribution to the 15th IIR Gustav Lorentzen conference 2022, monitoring data of a low temperature refrigerating system were used to compare the results of these indirect measuring methods to directly measured reference data. For the further development of two of these methods, the compressor model is adjusted and the refrigerating plant model is enhanced with an additional criterion for filtering invalid states of the refrigerating system. Consequently, the deviation from the reference is further reduced. Moreover, additional data for a longer period was collected in order to confirm the identified behaviour of the indirect measuring methods. In a next step, a wider range of operating conditions will be investigated.