Experimental investigation of 3-kW organic Rankine cycle (ORC) system subject to heat source conditions: A new appraisal for assessment

Highlights: • Experiment of organic Rankine cycle is studied and evaluated with a novel index. • The proposed assessment index includes effects of heat recovery and efficiency. • Effects of inlet temperature and flowrate of heat source on system are examined. • The evaporating temperature appreciably reduces heat recovery effectiveness. • The heat recovery is more sensitive than efficiency for a low temperature difference. In this study, experiments are carried out to examine the 3 kW organic Rankine cycle (ORC), investigating the influence of the heat source temperature and the flowrate of heat source on the system performance and heat recovery. Firstly, the behaviors of the evaporator and expander are examined. The efficiency and heat recovery effectiveness further discussed. The results indicated that the inlet temperature of the heat source exhibits a higher sensitivity on system efficiency than the flowrate due to the contribution of the heat transfer rate and power output. The system efficiency increases from 5.2% to 5.6% when the inlet temperature increase. However, the higher heat transfer rate leads to reduction of heat recovery from 60% to 40%. It indicated that the system efficiency may rise while the decrease in the heat recovery effectiveness are encountered with the increase in evaporating temperature. To tackle this inconsistency, the present study proposes a new appraisal, total heat recovery efficiency, defined by the multiplication of system efficiency and effectiveness. The proposed appraisal is more appropriate from the perspective of the heat recovery. Based on the experimental data, the proposed index can assess the performance of ORC subject to inlet temperature of heat source.