Desirable Properties of Refrigerant: A refrigerant must have some of the following desirable properties for it to be treated as a Marine Refrigerant.
What are the Desirable Properties of Refrigerant?
Here are some of the Desirable Properties of Refrigerant
1. Low Boiling Point: To produce a cooling effect, a liquid has to vaporize at the evaporator coil. So it has to vaporize easily at the evaporator coil, otherwise, the compressor will have to create too much vacuum to cause the liquid to vaporize. So a refrigerant must have a Low Boiling Point for an easy start of the system.
2. Low Condensing Pressure: The pressure to which the compressor has to compress the drawn gases to convert them back into the liquid at the condenser should be below. Thus the requirement of ” Condensing pressure” for vapour should be below. Therefore, the refrigerant vapour should be easily condensable.
3. High Specific Enthalpy of vaporization: Every kilogram of liquid refrigerant vapourised at the evaporator coil should take away a large amount of heat, i.e. ‘Specific Enthalpy of Vaporisation’ (latent heat) of refrigerant should be high to gain more heat from the evaporator. Otherwise, the mass flow rate will be high.
4. High Critical Temperature: Once the evaporated gas is compressed, the temperature of seawater should be low enough (below the critical temperature of the refrigerant) to be able to condense these gases to liquid form. Thus ‘Critical Temperature’ of the refrigerant should be high.
5. Low Specific Volume: The vapour produced after vaporization of the liquid at the evaporator coil should occupy minimum volume, to keep pipeline diameter, compressor size, etc. small and compact. Thus refrigerant vapour should have a low ‘Specific Volume’ to accommodate less space in line.
6. Non-Corrosive and Stable: The refrigerant must be system loving and does not react with other components. It must be of stable nature
7. Non-flammable and Non-explosive: It should catch fire when coming in direct or indirect contact of air.
8. Compatible with crankcase oil, oil seals, gaskets, metal involved, etc.: It must be non Miscible to lube oil, crankcase oil to a certain extent.
9. Easy leak detection possible: To avoid any major leaks on the refrigerant, it must be easy to detect any leak either by odour or colour.
10. Non-Toxic: In case of any leak, it must not have any harmful effect on the health of human beings around.
11. Environmental friendly: It should not cause any damage to our enviroment.
12. Cheap and Easily available: It should be easily available so that it can refilled from everywhere.
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.