Final work :Experimental and numerical characterization of an ORC cycle for an automotive application

Abstract

As a result of increasing environmental awareness, the European Union has implemented new rules. The automotive industry is working on new technologies to reduce its emissions. The Organic Rankine Cycle is one solution that has been studied during the last years as a technology to use the waste heat from the engines. Current work deals with designing, fabricating, and testing an ORC cycle to exploit the waste heat of 4.6kW, available from the coolant of an electric car. For that, a steady analysis is performed under ideal conditions to decide on the refrigerant and on the components to be purchased to later work in a test campaign. R134a is chosen as the cycle refrigerant, due to its superior performance and less cost compared to other refrigerants considered in this study. This campaign was carried out during the execution of the thesis and gave a clear idea of the suitability of the solution. A total of 43 steady points have been collected during the experimental campaign in which the evaporating temperature was in the range of 58.5 to 69.3 $\degree$C. Due to poor performance of the pump, global cycle efficiencies were negative. A maximum of 90W could be extracted from the expander due to limited pressure ratios that could be achieved with the pump. Further analysis has shown that the expander employed is oversized for the nominal volumetric flow. At the maximum rpm of the pump, which is 3300 rpm, gross efficiency of the cycle was measured to be 1.9%. Limitations of the current setup and suggestions to improve are also discussed.