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Bachelors Degrees
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What is meant by degree of superheat?


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November 11, 2009 3:45PM

First of all, the term "superheated" generally refers to a vapor. This explanation refers to superheated vapor only.

Superheat is the difference (in degrees of temperature) between a liquid's boiling point and the superheated vapor's actual temperature.

For example; at sea level, the boiling point of water is 212ºF. As long as the temperature is 212ºF, you will have both liquid and vapor present. If you continue to add heat to the liquid/vapor mix, all the liquid will eventually become vapor. Additional heat added after no liquid remains will begin to increase the temperature above 212ºF. This resulting vapor is superheated.

If you measure the temperature of water vapor to be 220ºF at 1 ATM, the vapor is superheated by 8ºF.

The same analysis is true for any liquid/vapor, at any pressure and for any other temperature scale. i.e. R22 refrigerant is "saturated" (meaning both liquid and vapor are present) at 32ºF and 58PSIG. If you measure the pressure of R22 at 58PSIG but measure the temperature at 45ºF, you have measured 13 degrees of superheat.

I hope this answer is useful to you.

Bama Cracker

Degree of superheat is the difference between the superheated temperature and the saturated temperature of the steam .