This is a synthetic element and does not occur in nature. It is produced through neutron absorption by fertile U238 and subsequent beta decays. Plutonium melts at 640*C. It is extremely toxic and emits alpha rays. Due to its naturally fissionable , plutonium continues to emit high energy gamma and other radiation. The metal is chemically more reactive than uranium and has a poor resistance to corrosion. It has six allotropic forms. The chief application of plutonium is in the production of atomic weapons and also in breeder reactors. Since some plutonium alloys and compounds emit neutrons, adequate health protection is necessary while using these materials.
Advantages Of Air Refrigeration : 1. The refrigerant used namely air is cheap and easily available. 2. There is no danger of fire or toxic effects due to leakages. 3. The weight to ton of refrigeration ratio is less as compared to other systems. Disadvantages Of Air Refrigeration : 1. The quantity of Refrigerant used per ton of refrigeration is high as compared to other systems. 2. The COP of the system is very low. Therefore running cost is high. 3. The danger of frosting at the expander valves is more as the air contains moisture content.
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