Exergy analysis of two stage organic Rankine cycle generation power system with co-condenser

doi:10.16085/j.issn.1000-6613.2021-0019

Abstract

Abstract:

Organic Rankine cycle (ORC) power generation is one of the effective ways to convert medium and low temperature heat sources into high-grade electric energy. For the subcritical saturated organic Rankine cycle system with heat source temperature of 100—150℃, four kinds of organic working fluids are selected to study. Firstly, the variation trend of heat source temperature and working fluids on the exergy efficiency and heater exergy efficiency of single stage/two stage power generation system is analyzed, and then the influence of pinch temperature of two stage system on the exergy efficiency of system and heater is analyzed. The main conclusions are as follows: the exergy efficiency of dual cycle system and heater is significantly higher than that of single cycle system at the same heat source temperature, when R245fa is used as working fluid. For example, when the heat source temperature is 130℃, the exergy efficiency of the system is increased by 14.45%. The exergy efficiency of the system and heater decreases with the increase of the pinch temperature; when the pinch temperature increases at different heat source temperatures, the reduction of the exergy efficiency of the system and heater is nearly equal; when the narrow point temperature difference increases by 2℃, the exergy efficiency of the system decreases by about 1.9%. The exergy efficiency of the system and heater is analyzed when four kinds of organic working fluids are used in the dual cycle system, and the exergy efficiency increases with the increase of heat source temperature. When the temperature of heat source is 100℃ and 150℃, the difference of system exergy efficiency between working fluids R245fa and R601 is 0.89% and 3.54%, respectively, and the difference of exergy efficiency of the heater is 0.49% and 4.82%, respectively.

Key words: two stage cycle generation power system, exergy analysis, pinch temperature, organic Rankine cycle, organic working fluids

摘要：

有机朗肯循环（ORC）发电是将中低温热源转化为高品位电能的有效途径之一。本文针对热源温度为100~150℃的亚临界饱和有机朗肯循环系统，选用4种有机工质，首先分析热源温度和工质对单级/双循环发电系统?效率和加热器?效率的变化规律，进而对双循环系统窄点温差对系统和加热器?效率的影响进行分析。主要结论包括：在相同热源温度下，R245fa为工质时，双循环系统及加热器的?效率相对于单循环系统的?效率大幅提升，在热源温度为130℃时，系统?效率提高了14.45%。随着窄点温差的增大，系统和加热器?效率减少；不同热源温度下窄点温差增大时，系统和加热器?效率的减小量接近相等，当窄点温差增加2℃，系统?效率平均减少1.9%左右。分析双循环系统采用4种有机工质时系统和加热器?效率，发现?效率都随热源温度增加而增大；当热源温度为100℃和150℃时，工质R245fa相对于R601的系统?效率相差为0.89%和3.54%；对应加热器的?效率相差为0.49%和4.82%。

关键词: 双循环发电系统, ?分析, 窄点温差, 有机朗肯循环, 有机工质

CLC Number:

TK115

LIU Guanglin, XU Jinliang, MIAO Zheng. Exergy analysis of two stage organic Rankine cycle generation power system with co-condenser[J]. Chemical Industry and Engineering Progress, 2021, 40(12): 6656-6662.

刘广林, 徐进良, 苗政. 共冷凝器双循环有机朗肯发电系统㶲分析[J]. 化工进展, 2021, 40(12): 6656-6662.

Figures/Tables 12

References 21

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工质	标准沸点/℃	临界温度/℃	临界压力/MPa	ODP	GWP
R600a	-11.7	134.7	3.64	0	20
R245fa	15.1	154.1	4.43	0	1020
R123	-0.5	152.0	3.8	0.012	53
R601	27.8	187.4	3.39	0	11

工质	标准沸点/℃	临界温度/℃	临界压力/MPa	ODP	GWP
R600a	-11.7	134.7	3.64	0	20
R245fa	15.1	154.1	4.43	0	1020
R123	-0.5	152.0	3.8	0.012	53
R601	27.8	187.4	3.39	0	11

数据来源	加热器?效率/%	系统?效率/%
文献［21］	80.5	33.51
本文模拟	80.49	33.51

数据来源	加热器?效率/%	系统?效率/%
文献［21］	80.5	33.51
本文模拟	80.49	33.51

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