Working Medium Selection for Flue Gas Heat Source Organic Rankine Cycle Systems

Under the condition of the heat source of flue gases being at different temperatures,studied was the relationship between the thermal efficiency and the organic working medium of a subcritical organic Rankine cycle power generation system and applications of the organic working medium thus optimized in a recuperator system.It has been found that for a subcritical organic Rankine cycle system,at given heat source parameters,when the temperature of the organic working medium at the inlet of the expander is kept constant,the system will attain its maximal efficiency with the working medium keeping in the dry saturated steam state at the inlet of the expander and in the meantime,the organic working medium R245fa is superior to other working media for a low temperature flue gas heat source organic Rankine cycle power generation system when the system efficiency,flammability and toxicity of the organic working medium etc.factors are compared.The efficiency of the system can be up to 10.2%.When the heat source pertains to high temperature flue gases,the organic working medium R601a is relatively superior,however,because it is highly flammable,it is necessary to study a new type working medium suitable for high temperature heat sources.The efficiency of an organic Rankine cycle power generation system with a recuperator is relatively higher than that of a simple cycle power generation system,of which the main causes lie in a decrease of the energy loss during the heat exchange at the side of the condenser.