Thermodynamic Analysis of an Organic Rankine Cycle with Cooling Water Power Consumption Considered

doi:10.3901/JME.2018.18.180

Abstract

Abstract: The thermal efficiency of organic Rankine cycle (ORC) is usually low because of the abundant rejection heat rate in the condensation process. Besides, the cooling water power consumption influences the system performance significantly. Considering the cooling water circulation, the ratio for cooling water power consumption is defined as the value of water pump power consumption per power output of the loop, and the effects of important factors have been investigated. The results show that the ratio for cooling water power consumption declines with increasing evaporation temperature, whereas it rises with increasing condensation temperature. With the ambient temperature of 20℃ and the initial temperature for cooling water of 25℃, the expander has the minimum irreversible loss of 19.03 kW and the system has the minimum irreversible loss of 140.32 kW. The influence of temperature rise for cooling water on the ratio for cooling water power consumption is significant. It has a nonlinear fall with decreasing the temperature rise of cooling water, and increases linearly with increasing water pump head. When the temperature rise for cooling water is less than 8 K or the water pump head is more than 15 m, the ratio for cooling water power consumption is larger than 5%, which manifests that the cooling water power consumption cannot be neglected for the ORC system.

Key words: circulating cooling water, exergy analysis, net power output, organic Rankine cycle (ORC), waste heat recovery

CLC Number:

TK123

ZHU Yilin, LI Weiyi, SUN Guanzhong. Thermodynamic Analysis of an Organic Rankine Cycle with Cooling Water Power Consumption Considered[J]. Journal of Mechanical Engineering, 2018, 54(18): 180-186.

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