Effect Of Superheating of suction Vapour-(before compression)

Effect Of Superheating of suction Vapour-(before compression)
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Effect Of Superheating of suction Vapour-(before compression)


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A vapour compression cycle with superheated vapour before compression is shown on T-s and p-h diagrams respectively. In this cycle, the evaporation starts at point 4 and continues upto point 1', when it is dry saturated. The vapour is now superheated before entering the compressor upto the point 1. The vapor superheat has the following effects on the refrigeration cycle: (a) It increases the refrigeration effect per unit mass of the refrigerant from H1' - H4 to H1 - H4. (b) The specific volume increases from V1' to V1. This implies the reduction in mass flow rate for the same displacement volume of the compressor. (c) The energy for compression of refrigerant vapour will increase due to the diverging nature of the isentropic lines. (d) It is a usual practice to admit slightly superheated vapor before the beginning of compression to avoid the possibility of wet compression. Wet compression is undesirable as there may be accumulation of liquid inside the cylinder, which in turn will wash away the lubricant resulting in sever mechanical difficulties. Thus, to avoid this, a 5 to 20 K superheat of the refrigerant is always desirable. 

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Last Answer : Ans: d

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Adiabatic compression of a saturated water vapour makes it (A) Supersaturated (B) Superheated (C) Both (A) and (B) (D) Neither (A) nor (B)

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In vapour compression refrigeration system, if the evaporator temperature and the condenser temperatures are -13°C and 37°C respectively, the Carnot COP will be (A) 5.2 (B) 6.2 (C) 0.168 (D) Data insufficient, can't be found out

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