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Refrigeration Procedures & Environmental Impacts - Coggle Diagram
Refrigeration Procedures & Environmental Impacts
Defrosting
Refrigeration plants are susceptible to moisture from the air icing up the outside of evaporator coils
This ice build up prevents latent heat absorption and evaporator efficiency falls
Natural Defrosting - occurs every 6 - 9 months when the ship will de store for cleaning / maintenance and ice will melt naturally
Hot Gas Defrosting - hot, high pressure vapour is passed through the evaporator to defrost the coils, performed for max one hour a day to avoid oil cooking and stop room temperaure rising too much
Electrical Heating Coils - using either rod type or wrap around coils in the evaporators, refrigerant flow is stopped and heaters are ran for an hour to prevent oil cooking
Montreal Protocol (1987)
Agreed to phase out ODS gases, such as CFC which ceased production in 1995 and all refrigerants must be recovered for processing and not released into the environment
27 countries signed in 1987, 60 in 1980 and 70 in 1991 with notable exceptions being China and India
Global Warming
aside from Ozone impacts, these refrigerants introduce greenhouse gases into the environment that raise the Earth's core temperature
Kyoto (1997) - agreements to limit greenhouse gases (CO2, HFC's & PFC's)
Leak Detections
Infra Red Leak Detection Systems - a fitted system around the atmosphere at various points around machinery with a visual indicator outside the compartment
Oil Slicks - over a period of time oil leaks will be visible, machinery is painted white to aid this
Spectrolene Dye - added to the oil, this will further highlight leaks when paired with a UV lamp
Snoop - soapy water is applied to suspect areas
Halogen Leak Detector - portable electric device that detects leaks by running around pipes, however it is extremely sensitive and can be interfered with via normal air flows
Lubrication
The Compressor which is basically a positive displacement pump, requires lubrication
OM 70 - a general purpose refrigerant oil, SUNISO 3GS - a synthetic oil used on type 23's and T BOATS, SW 68 - a synthetic oil using R134A
Due to the requirement for it to operate at low temperatures, the wax is removed making it hydroscopic
To rectify it's hydroscopic properties, leaking or already open containers are discarded, containers range from 500ml - 5ltr and any oil left over need to be discarded in accordance with MARPOL regulations
Oil is added to the sump by the sump filler plug, hand pump, dosing pot, ensuring oil is cleared from the ejector lines