Steam Boilers, Engines, Nozzles and Turbines
The critical pressure ratio (p₂/p₁) is given by

(p₂/p₁) = [(n + 1)/2] n - (1/n)
(p₂/p₁) = [(n - 1)/2] n + (1/n)
(p₂/p₁) = [2/(n - 1)] n/(n + 1)
(p₂/p₁) = [2/(n + 1)] n/(n-1)

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Steam Boilers, Engines, Nozzles and Turbines
In fire tube boilers

The flames and hot gases pass through the tubes which are surrounded by water
Forced circulation takes place
None of these
Water passes through the tubes which are surrounded by flames and hot gases

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Steam Boilers, Engines, Nozzles and Turbines
Which is not the correct statement about moisture in coal?

In some coals moisture may be present up to 40%
Some moisture in coal helps in better burning which is not possible with completely dry coal
Inherent moisture and surface moisture are different things
It increases thermal efficiency

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