Trends in patent applications relating to organic Rankine cycle

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. (C) 2014 Elsevier Ltd.