USCG Exam PracticeThermodynamics and heat exchangers
Non-condensable gases accumulating in a main condenser will have which direct effect on plant operation?
- A. They increase the latent heat of vaporization of the exhaust steam, improving heat transfer
- ✓ They blanket the tubes, raise back-pressure, and reduce heat transfer, lowering turbine efficiencyCorrect
- C. They lower condenser vacuum by reducing the partial pressure of steam in the shell
- D. They contaminate the condensate with chlorides, causing boiler scale
Why B is correct
DOE-HDBK-1018 Vol.1 §2-3 states that non-condensable gases must be continuously removed or they blanket the tubes, raise back-pressure, and reduce heat transfer. Chloride contamination results from seawater leaks, not non-condensable gases.
Cited:DOE-HDBK-1018 Vol.1 §2-3