Experimental Investigation of NH3/CO2 Cascade system and comparison to R404A system for supermarket refrigeration

• This study investigates the performance of an NH3/CO2 cascade system for supermarket refrigerationapplication in a laboratory environment. The tested CO2 system is designed and scaled to fulfil therequirements of an average size supermarket in Sweden. Possibility for hot gas defrost in the freezers hasbeen investigated and compared to the conventional electric heaters defrost method. Two cascade condenserarrangements have been evaluated. The cascade system has been compared to R404A system installed in thesame laboratory.The results show that connecting the cascade condenser via thermosyphon or hot gas de-superheatarrangements yields good system stability and heat transfer performance. Hot gas defrost successfullydefrosted the freezer evaporator but with long period and higher energy consumption compared to theconventional electric defrost method. The tested cascade system had up to 60% higher total COP comparedto the R404A system installed in laboratory.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik -- Energiteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering -- Energy Engineering (hsv//eng)

Nyckelord

SRA - Energy

SRA - Energi

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