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Superheated

Superheated. Superheated Steam: Water vapor at a temperature higher than the boiling point. The number of degrees the temperature exceeds the boiling temperature is the degrees superheat.

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Superheated

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  1. Superheated

  2. Superheated Steam: Water vapor at a temperature higher than the boiling point. • The number ofdegrees the temperature exceeds the boiling temperature is the degrees superheat. • Additionof heat to superheated steam could increase the superheat at constant pressure or change boththe pressure and temperature at constant volume. • Removing heat will allow the temperature todrop to the boiling temperature where the temperature will remain constant until all the vapor has condensed. • Both temperature and absolute pressure mustbe specified to accurately define the degree of superheat.

  3. Properties of superheated steam

  4. Berapa besar panas yang dibutuhkan untuk merubah 1 lb air yang bersuhu 70◦F menjadi steam yang bertekanan14.696 psia dan bersuhu 250◦F? • Pertama : tentukan keadaan steam pada 14.696 psia and 250◦F. • Pada14.696 psia, titik didih sebesar 212◦F. • Steam pada250◦F dan14.696 psiaadalah superheated steam. • Dari tabelsuperheated steam, h pada 250◦F sebesar1168.8 BTU/lb. • Panas yang diperlukan= hg pada250◦F dan14.696 psia − hf at 70◦F • = 1168.8 BTU/lb − 38.05 BTU/lb • = 1130.75 BTU/lb

  5. Berapa panas yang harus diambil untuk mendinginkan superheated steam pada14.696 psia dan500◦F menjadi 250◦F pada tekanan yang sama? • Dasar: 1 lb steam • Panas yang harus diambil= q = h pada14.696 psiadan 500◦F − hg pada14.696 psia dan 250◦F • = 1287.4 − 1168.8 = 118.6 BTU/lb • Superheated steam sbg media pemanas kurang efisien. Perubahan suhu sebanyak250◦F hanya memberikan panas sebesar 118.6 BTU.

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