CO_2近零排放固体氧化物燃料电池冷热电联供系统的性能分析

Performance Analysis of the Near Zero CO_2 Emissions Tri-generation System Based on Solid Oxide Fuel Cell Cycle

为了提高SOFC联供系统的综合利用效率和降低CO_2捕集能耗,提出一种基于SOFC循环的CO_2近零排放冷热电联供系统。建立了系统数学模型,给出了设计工况下各点的热力参数值,分析了燃料利用率、空燃比、燃料电池入口温度与工作压力变化对系统性能的影响。结果显示,在设计工况下,SOFC发电效率、联供系统净发电效率和一次能源利用率分别为51.59%、53.84%和72.01%,与没有CO_2捕集的联供系统相比,净发电量降低了3.66%,一次能源利用率降低了2.05%。变参数研究结果显示,随着工作压力的增加,SOFC的发电效率增大,而系统净发电效率和一次能源利用率减小;另外,增加空燃比会降低SOFC发电效率、系统净发电效率和一次能源利用率,所以在保证SOFC在正常工作情况下应选择较小的空燃比。在燃料利用率和阴极入口温度变化中,SOFC的输出功率和输出电压先增加后减少,而阳极入口温度变化对SOFC性能影响较小。

In order to improve solid oxide fuel cell （SOFC） combined system efficiency and reduce CO2 capture energy consumption, a novel near zero CO2 emission tri-generation system based on SOFC cycle was proposed. The mathematical model was developed, and the thermodynamic parameters of each point under design conditions were given. The effects of fuel utilization ratio, air-fuel ratio, SOFC gas inlet temperature and operating pressure on system performance were investigated. Results show that the SOFC electrical efficiency, the tri-generation net power efficiency and the primary energy ratio under the design conditions are 51.59%, 53.84% and 72.01%, respectively. Compared with the system without CO2 capture, the new system net power output and the primary energy ratio are reduced by 3.66% and 2.05%, respectively. It is also showed that the SOFC electrical efficiency increases, but the system net electrical efficiency and the primary energy ratio decrease as the working pressure increases by the varying parameters study. Furthermore, the SOFC electrical efficiency, the tri-generation net efficiency and the primary energy ratio decrease as the air-fuel ratio is increased, and therefore the smaller air-fuel ratio is recommended on the condition that SOFC is under normal operation. When the fuel utilization ratio and the cathode inlet temperature are increased, the SOFC power output and actual voltage increase firstly and then decrease; however, the anode inlet temperature variation has little influence on SOFC performance.