The design and installation has just been completed on what was to become the first hospital catering facility refrigeration system to run with CO2 in the UK. + IMAGE GALLERY
A CO2 unit supplied by Green & Cool has been installed and commissioned by CCS Refrigeration, through principle contractor Aggora on behalf of Compass Group, trading as Medirest to provide for the on site catering requirements of patients, restaurant and hospital staff at the Homerton University Hospital in London, UK.
The water supply for the large CO2 chiller coldroom is run from the existing ammonia chillers supplied by J & E Hall and installed some 75 metres away. The complete system, hence, runs on natural refrigerants, with the ammonia system chilling water and CO2 cooling the evaporators.
The two existing ammonia chiller units each with 0.5 MW cooling capacity, which cool water from 12°C to 6°C, enabled the design of a sub-critical system. Nonetheless, due to the relatively high condensing temperature, CCS Refrigeration required trans-critical compressors even though the system would run sub-critically year round.
Swedish CO2 refrigeration specialist Green & Cool provided a CO2 unit built in the specifications of CCS. The overall system features:
Baltic DO23MT CO2 trans-critical unit by Green & Cool, with a 100% back up twin compressor system
Water-cooled plate heat exchanger
Green & Cool CO2 control system, with user-friendly touch screen
Danfoss AKVH pulse valves
Searle kecx-70L evaporators
Leak detectors in the coldroom by CPC: the leak detection system was installed first prior to commissioning and features a battery back up in case of power failure.
Coldroom controls provided by RDM
LED tube lighting
e-cubes to the air on probes
Energy and emissions savings
Significant energy savings associated with the new system was the reason behind opting for it.
The energy savings over a conventional system have been calculated to be 16.7% over the course of one year, not including the savings from the installed LED lighting or fitted e-cubes. LED tube lighting is again very energy saving. Finally, by installing e-cubes to the air on probes a further 15% energy savings are realised compared to when conventional probes reading air temperature are being used.
Over a ten year lifespan, some 628,000 kg of CO2 emissions will be saved thanks to the use of a CO2 system and compared to a standard HFC system.
More CO2 projects in the pipeline by CCS
CCS have a number of CO2 projects on the books at the moment, with Café Royal London and Kapsarc SA to name a few.