How do the internal flue tube diameters of a Lancashire boiler compare to its outer shell_________________?
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Answer: E. two-fifth
Explanation
Internal flue tube diameters in a Lancashire boiler are constructed to be approximately two-fifths of the outer shell diameter. This proportional sizing allows two large combustion tubes to fit securely side-by-side within the cylindrical outer shell. Maintaining a two-fifths ratio balances the required internal heating surface area with adequate surrounding water volume. Lancashire boilers feature twin internal longitudinal fire tubes that carry hot combustion gases through the surrounding water. Proportioning internal components correctly ensures even heat transfer and prevents thermal stress concentrations in the shell. Fire-tube boiler designs rely on maximizing internal flue surface areas to enhance overall thermal operational efficiency.
Option A suggests a one-half ratio, which would prevent two flues from fitting inside the outer shell safely. Option B proposes a one-third ratio, underutilizing the available cross-sectional space within the outer cylindrical pressure vessel. Option C specifies a one-fourth ratio, which is too small to accommodate efficient industrial combustion burners.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
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