UPDATED: Integrating CO2 and trigeneration technology for supermarkets

By R744.com team, Jan 11, 2011, 09:27 3 minute reading

Brunel University in the UK along with 14 industrial partners, including Danfoss, Emerson and Bock, have announced an innovative energy system for retail food and manufacturing facilities that integrates CO2 and trigeneration technologies. The system has the potential to realise 30% energy savings and over 40% emission savings compared to conventional systems. Details of the system were presented at a 1-day event organised by Brunel University on 11 November 2010.

Designed to meet the needs of medium and large size supermarkets for retrofit or new applications, the system uses the energy released by a combined heat and power system to drive a sorption (thermally driven) refrigeration system, which in turn is used in a cascade arrangement to condense CO2 refrigerant of a subcritical CO2 refrigeration system. This ensures operation of the CO2 refrigeration system in the subcritical region at all times and at a constant condensing temperature, ensuring thus high energy efficiency throughout the year.

Basic elements of the system include:
  • Combined heat and power (CHP) module: This can be based on an internal combustion engine driven by any fuel such as natural gas, biogas, diesel, or biodiesel or micro gas turbines, with the actual selection to be based on the specific requirements of the application.
  • Sorption refrigeration system: This can employ any type of sorption machine (absorption: ammonia-water; lithium bromide-water or adsorption: silica gel-water), depending on the temperature of the heat available from the CHP plant and the desired condensing temperature for the CO2 refrigeration plant.
  • CO2 refrigeration system: The refrigeration system uses CO2 as a secondary (volatile) refrigerant for the medium temperature (MT) cabinets and direct expansion (DX) for the low temperature (LT) cabinets. This maximises the system efficiency as the compressor power for MT refrigeration - which is the predominant load in a supermarket - is replaced by a much lower pump power to pump the liquid refrigerant to the refrigerated cabinets.

Impressive energy efficiency results

Laboratory tests have shown the LT system to deliver a steady state Coefficient of Performance (COP) of 4.0 at evaporating temperature of -32°C and condensing temperature of -7°C.

The COP of the MT system is very high, exceeding 50, due to the low power requirement of the pump. System simulation and energy analyses of a conventional R404A system and the integrated CO2-trigeneration system in a 5,000 m2 sales area supermarket has shown the integrated energy system to produce energy savings of 30% and greenhouse gas emission savings of 43%.

Watch video on the system

A 3D modelling video depicting the tri-generation system at MediaCityUK, a 0.82km² (200-acre) property development based on the media industry, located in Greater Manchester, has been put together by VitalEnergi.

Event providing more details on the technology and CO2 refrigeration

Details on the integrated system as well as on the latest equipment and application developments on CO2 refrigeration were presented at a 1-day event organised at Brunel University on 11 November 2010. The event aimed to present the results of a three year project on the ‘Integration of CO2 Refrigeration and Trigeneration Technologies’ funded by the UK Department of Food and Rural Affairs (Defra) under the LINK scheme.

Some of the presentations included:
  • CO2 Refrigeration in Supermarkets - Tesco approach and experiences, Andy Campbell, Tesco
  • Recent Developments in CO2 Refrigeration Compressors
  • Manuel Froeschle/Guenter Vollrath, Bock
  • Recent Developments in CO2 Controls and System Diagnostics, Michael Engelbright, Danfoss
  • Integration of CO2 Refrigeration and Trigeneration Systems for Energy and GHG Emission Savings in Supermarkets - AFM251, Prof. Savvas Tassou, Brunel University


By R744.com team (@r744)

Jan 11, 2011, 09:27

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