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CHILLERS REFRIGERANTS


An important strategy used to prevent explosions in process systems where flammable gases or vapours may be present, is to lower the oxygen concentration by adding an inert gas


where available the alarms should also interface with the structure’s building management system (BMS). The gas detectors should be calibrated to 10% of the Lower Flammability Limit (LFL), expressed in volume per cent. This is the lower end of the concentration range at a given temperature and pressure for which air/ flammable refrigerant mixtures can ignite. A remote switch should be provided


outside and near to the machinery room door, for isolating all electrical equipment not protected for use with flammable refrigerants, and for stopping all machinery. An emergency lighting system should be provided to allow evacuation of personnel and for any necessary urgent operation of controls, suitably protected for use in hazardous areas. Power sockets should permit plug


Cooling Output kW COP


Power Input kW Run Hours


Load Factor %


Annual Energy Consumption kWh Cost of Energy £/KWh (2007 prices) Annual Running Cost £ Capital Cost £


10-year Running Cost £ 10-year life cycle cost £ 10-year saving £


Payback Period (years)


HC chiller 625 4.15


150.6 3,000 50


225,900 0.063 14,231 69,830 142,310 212,420 56,990 1.5


Hydrocarbon-based chiller life-cycle analysis: Church House, London (see box on page 44) 46 CIBSE Journal June 2012


HFC134a chiller 625


2.82


221.6 3,000 50


332,400 0.063 20,941 60,000 209,410 269,410 - -


removal only if the socket is isolated, and should be located above the level of the leak detectors. Fire extinguishers should be installed


in accordance with local fire authority requirements, and notices describing their correct usage should be posted. Clear emergency procedure signs are needed inside the chiller plant room and outside the access door. Water sprinklers for fire protection


should be installed in the chiller plantroom. Warning notices should be posted stating that smoking, naked lights or flames are prohibited. Further steps may be required to comply with national or local regulations. This procedure demonstrates that plant


rooms for chillers with large hydrocarbon charges can be designed and used safely through proper refrigerant handling, leak minimisation, mixture dilution, ignition prevention and overpressure venting. But, as the critics of HCs will be quick


to point out, this only applies to above- ground plant rooms. For basement plant rooms, where many chillers are currently located, the 1 kg of HC refrigerant restriction still applies. To overcome this restriction, Earthcare is now working on designs for inert atmosphere plant rooms. An important strategy used to prevent explosions in process systems where flammable gases or vapours may be present, is to lower the oxygen concentration by adding an inert gas, to the point where the fuel-air mixture is no longer flammable. The oxygen concentration at the limit of flammability is referred to as the limiting oxygen


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