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Consider the following Statements in respect of regenerative Rankine cycle: 1) Regeneration increases the efficiency of the cycle. 2) The boiler capacity is increased for a given output. 3) The capacity of the condenser is reduced. Which of the above statements are correct?

Consider the following Statements in respect of regenerative Rankine cycle: 1) Regeneration increases the efficiency of the cycle. 2) The boiler capacity is increased for a given output. 3) The capacity of the condenser is reduced. Which of the above statements are correct? Correct Answer 1, 2 and 3

Explantion:

The regeneration in the Rankine cycle is done by bleeding the steam from the high-pressure turbine after the partial expansion of the steam in the turbine, and it preheats the condensed liquid before it returns back to the boiler.

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In this way, the amount of heat added at low temperatures is reduced. Therefore the mean effective temperature of heat addition is increased and cycle efficiency is increased.

In the case of the ideal regenerative cycle, the best result is obtained by heating the feed-water to a temperature equal to the saturation temperature corresponding to the boiler pressure. To carry out the ideal regenerative process the regenerative heat exchanger is called a feed-water heater.

The boiler capacity is increased for a given output, the amount of steam which does not get fully expanded in the turbine leads to some reduction in the work output but the amount of steam returning to the boiler remains the same therefore if the work output is to remain constant then the boiler capacity has to be increased.

The capacity of the condenser is reduced because a small fraction of the steam is not reaching the condenser now.

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