Ship refrigeration systems play a vital part on ships carrying refrigerated cargo and victuals for the crew or passengers. Refrigeration prevents any damage to the cargo or decay of perishable foods, like growth of micro-organisms, oxidation, fermentation and drying out of cargo. The temperature of the sometimes sensitive cargo is controlled by the ship’s refrigeration plant. As the main purpose of vessels carrying refrigerated cargo is to ensure the cargo is transported in good and healthy condition, it is of uttermost importance that the refrigeration system works perfectly at all times.
How does a ship refrigeration system work
A refrigeration system needs to remove heat from an enclosed region. This is achieved via the refrigeration cycle, which consists of five components:
- The refrigerant;
- The compressor;
- The condenser;
- The evaporator;
- The expansion device.
The refrigerant starts as a gas and is compressed in the compressor, which increases its temperature dramatically. Thereafter, the condenser cools the hot high pressure refrigerant and this way the refrigerant turns into a liquid. Next, the evaporator boils the refrigerant back to a gas, at a very low temperature. The change from liquid to gas absorbs the heat from the evaporator, which in turn removes the heat from the area to be cooled, thereby lowering its temperature. Hereafter, the refrigerant is returned back to the compressor and the refrigeration cycle starts again.
Influence of the European F-gas regulation on refrigeration systems
Many refrigeration systems now use R22 as a refrigerant. R22 is one of the ozone depleting HFCs that may not be applied anymore in new systems as of 2004, and, starting 2015, refrigeration operations like refilling with HFCs aren’t allowed anymore either. This means that as long as the systems works, there is nothing to worry about. In case of defects, the consequences depend on the type of refrigerant. To bypass this problem, we have been researching alternatives for R22. We have come to the conclusion that the best substitute would be Propane (R290). Propane has very similar thermodynamic behavior to R22 and it is a natural refrigerant. By using R290 as a refrigerant, the environmental impact is reduced, because R290 has no ODP (Ozone Depletion Potential), a very low GWP (Global Warming Potential) and an assumed equal energy efficiency to R22. Propane is a flammable refrigerant though, and therefore cautious handling of the refrigerant is required. The most important safety concern is toensure that in case of a leakage the refrigerant doesn’t ignite. Therefore, the solution developed by Heinen & Hopman is to place the cooling system inside a casing, so when a leakage occurs, the possible explosive atmosphere is located inside the casing. By using an ATEX fan, the casing can be ventilated so that the mixture of gas and air can be discharged outside the casing.
Feel free to contact us for more information regarding ship refrigeration systems. Our skilled employees are eager to inform you.