The Organic Rankine Cycle System, Its Application to Extract Energy From Low Temperature Waste Heat

Abstract

The conservation of energy by its recovery from low temperature waste heat is of increasing importance in today's world energy crisis. The Organic Rankine Cycle is a cost efficient and proven method of converting low temperature (200-400o F) waste heat to mechanical and/or electrical energy. Applying the Organic Rankine Cycle technology to typical liquid and mixed component condensing streams is described using actual examples. Selection of the organic working fluid is explored. The Rankine Cycle efficiency is directly dependent upon the temperature difference between its evaporating and condensing phases. The evaporating level is set by the heat source; therefore, to maximize efficiency, it is essential to obtain the lowest condensing temperature practical. Various condensing schemes are discussed emphasizing methods of optimizing the net output of the total system. Several Organic Rankine Cycle commercial applications are summarized with experience and general performance given. The economics and optimization techniques in typical applications including multiple heat sources are discussed.