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Dynamic numerical modelling of a single stage dual temperature R744 ejector-supported refrigeration unit for last mile delivery.

Number: 0810

Author(s) : FABRIS F., BODYS J., MARINETTI S., MINETTO S., SMOLKA J., ROSSETTI A.

Summary

A novel design of a R744 vapor-compression refrigeration unit is proposed and developed to provide cooling capacity at two different temperature levels, in the range of 4-5 kW of MT refrigeration at 0°C and 1-2 kW of LT refrigeration at -20°C, inside the insulated box mounted on a typical medium-size refrigerated truck. Such a system can be employed for multi-temperature (chilled and frozen) goods transport to enhance the range of ambient conditions served with highly efficient operation during last-mile deliveries in urban environment.
The main innovation of the proposed cycle is related to the presence of a single compression stage with two different evaporation levels. Firstly, the cooling system design is based on the implementation of a MT ejector, with the purpose of energy efficiency improvement of the system due to the consequent reduction of the compressor pressure ratio. Secondly, an implemented LT ejector allows for the production of LT cooling effect with a single stage compressor. The system can switch to a back-pressure cycle once the ambient temperature is not sufficient to sustain the ejector cycle. On the other hand, the use of an ejector for the LT cycle allows to extend the application field of the single stage compressor to high ambient temperatures.
A dynamic numerical model of the refrigerating system has been developed to assess the system performance in ejector and back pressure mode. The numerical model was also used to characterize the system pull-down from ambient temperature.

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  • Original title: Dynamic numerical modelling of a single stage dual temperature R744 ejector-supported refrigeration unit for last mile delivery.
  • Record ID : 30031363
  • Languages: English
  • Source: Proceedings of the 26th IIR International Congress of Refrigeration: Paris , France, August 21-25, 2023.
  • Publication date: 2023/08/21
  • DOI: http://dx.doi.org/10.18462/iir.icr.2023.0810

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