No abstract

An organic Rankine cycle system with a preheater, evaporator, condenser, turbine, generator, and pump was used to study its off-design performance and operational control strategy. R245fa was used as a working fluid. The net power output is 243 kW and the system thermal efficiency is 9.5% under the design conditions. For an off-design heat source flow rate (m W ), the operating pressure was controlled to meet the condition that the R245fa reached the saturation liquid and vapor states at the outlet of the preheater and evaporator, respectively. The analytical results demonstrated that the operating pressure increased with increasing m W ; a higher m W yielded better heat transfer performance of the preheater and required a smaller evaporator heat capacity; and the net power output and system thermal efficiency increased with increasing m W . The net power output increased by 64.0% while the total heat transfer rate increased by only 9.2% for the studied range of m W . To conclude, an off-design operation is studied for a heat source flow rate which varied from -39.0% to +78.0% from the designed rate, resulting in -29.2% to +16.0% and -25.3% to +12.6% variations in the net power output and system thermal efficiency, respectively.

This study presents a statistical analysis of patent data to explore the technological developments of the Organic Rankine Cycle (ORC). The ORC is considered as one of the most economic and efficient ways to convert low grade thermal energy to electricity. Patent data of this study are obtained from the commercial database, Thomson Innovation, which can be used to search the patent information from many countries and offices. With searching, screening, and patent family integrating by the International Patent Documentation Center (INPADOC), 304 patents are analyzed in the present study. The results show that the patent applications increase slowly before 2006, but increase significantly from 2009 to 2011 mainly due to the contributions from the applications in China and Republic of Korea. The year of 2009 can be regarded as a significant distinction year for the ORC development and patent application. The results also show that the assignee from United States is the most prominent. On the other hand, the number of patent applications in China is the largest, indicating that China might be one of the most potential markets of the ORC. The main International Patent Classification (IPC) of the patent data is F01K (i.e., Steam engine plants; Steam accumulators; Engine plants not otherwise provided for; Engines using special working fluids or cycles). Most importantly, the technology life cycle of the ORC, based on the patent data, is at a growth stage.