Part-load optima in bottoming-cycles

Abstract

It is assumed that optimal steam conditions for a Rankine bottoming-cycle are those that produce the greatest power output. It is then demonstrated that optimal steam conditions are a function of steam-generator pinch-temperature difference, leading to the assumption that a designer of bottoming-cycles may begin with a chosen pinch-temperature difference. Further demonstration is given that the pinch-temperature difference must change in response to primary engine load changes, so that such load changes upset the optimal bottoming-cycle conditions found at primary engine-rated power. The consequences to the bottoming-cycle in terms of lost power capability are demonstrated and are found to be of small magnitude.