Abstract
Supermarket refrigeration units of the future have to be able to handle the entire energy flows and demands in
the supermarket building. Besides providing the cooling capacity for medium and low temperature display
cabinets, the heat pumping demands of the HVAC units should be integrated into the requirement
specification. This will reduce total investment and service costs. It will also reduce the total energy
consumption due to the possibility of direct utilization of surplus heat and advanced capacity controls during
AC mode. Therefore the system architecture of R744 commercial refrigeration unit has to be adapted to be
able to fulfil the required duties as energy efficient as possible, i.a. the control of evaporation temperatures and
evaporator outlet conditions at low, medium and AC temperature level. Integration of auxiliary evaporators for
heat pump & AC operation will be discussed and control strategies to further improve the multi ejector
enhanced parallel compression systems. Compared to HFC404A units, R744 ejector supported units with
parallel compression and a pressure lift of around 15 bar do have the highest energy efficiency values and
represent the next generation of R744 technology, which can be applied globally, significantly reducing both
direct and indirect greenhouse gas emissions.
the supermarket building. Besides providing the cooling capacity for medium and low temperature display
cabinets, the heat pumping demands of the HVAC units should be integrated into the requirement
specification. This will reduce total investment and service costs. It will also reduce the total energy
consumption due to the possibility of direct utilization of surplus heat and advanced capacity controls during
AC mode. Therefore the system architecture of R744 commercial refrigeration unit has to be adapted to be
able to fulfil the required duties as energy efficient as possible, i.a. the control of evaporation temperatures and
evaporator outlet conditions at low, medium and AC temperature level. Integration of auxiliary evaporators for
heat pump & AC operation will be discussed and control strategies to further improve the multi ejector
enhanced parallel compression systems. Compared to HFC404A units, R744 ejector supported units with
parallel compression and a pressure lift of around 15 bar do have the highest energy efficiency values and
represent the next generation of R744 technology, which can be applied globally, significantly reducing both
direct and indirect greenhouse gas emissions.