Study On A Combined System Based On SOFC/GT And Transcritical Carbon Dioxide Cycle

With the growth threat of energy and environment issues, clean energy and energy saving and emission reduction should be given to alleviate these issues.Solid oxide fuel cell is a device which directly converts the chemical energy of fuels into electrical energy through an electrochemical process. It has higher energy conversion efficiency which is not limited by the Carnot cycle. And it has advantages such as low pollutant emission, fuel flexibility, good variable load, and so on. SOFC/GT combined system is considered as the most critical study in this field.SOFC/GT exhaust gas has high grade waste heat to recover due to its high operating temperature. It is one of the most important research topics to combine the mid-or low-temperature waste heat recovery technique and SOFC/GT systems.Transcritical carbon dioxide cycle has a wide development and application potential in nuclear power, refrigeration and other fields. A combined system based on SOFC/GT and transcritical carbon dioxide cycle is proposed in which the SOFC/GT waste heat is recovered by transcritical carbon dioxide.First, SOFC, SOFC/GT and transcritical carbon dioxide cycle are summarized, and the present domestic and overseas investigation status of these are analyzed.Then, taking the example of internal reforming SOFC, SOFC mathematic model is established and verified. SOFC/GT model is developed, which performance is analyzed under design condition and variable parameter conditions. Three cycles model about transcritical carbon dioxide cycle is developed, and the performance of these three cycles is compared to achieve the appropriate cycle for recovering the waste heat of SOFC/GT. Mathematic model about SOFC/GT/TRCC is developed, and the performance of the system is analyzed under design and variable conditions. Results indict that SOFC, SOFC/GT and SOFC/GT/TRCC electrical efficiencies are 49.11%,69.13% and 75.34%, respectively.Finally, basing on the conception of exergy, exergy balance equation of SOFC/GT/TRCC is developed and exergy efficiency, exergy loss rate and exergy loss factor are calculated. To improve the SOFC/GT/TRCC performance, these parameters are analyzed.