Effect of Evaporation Temperature on the Performance of Organic Rankine Cycle in Near-Critical Condition

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
Yuping Wang ◽  
Xiaoyi Ding ◽  
Lei Tang ◽  
Yiwu Weng
Keyword(s):  
Thermal Efficiency ◽  
Critical Region ◽  
Critical Condition ◽  
Saturated Vapor ◽  
Organic Rankine Cycle ◽  
Small Variation ◽  
Rankine Cycle ◽  
Inlet Pressure ◽  
Working Fluids ◽  
Evaporation Temperature

Considering the large variations of working fluid's properties in near-critical region, this paper presents a thermodynamic analysis of the performance of organic Rankine cycle in near-critical condition (NORC) subjected to the influence of evaporation temperature. Three typical organic fluids are selected as working fluids. They are dry R236fa, isentropic R142b, and wet R152a, which are suited for heat source temperature from 395 to 445 K. An iteration calculation method is proposed to calculate the performance parameters of organic Rankine cycle (ORC). The variations of superheat degree, specific absorbed heat, expander inlet pressure, thermal efficiency, and specific net power of these fluids with evaporation temperature are analyzed. It is found that the working fluids in NORC should be superheated because of the large slope variation of the saturated vapor curve in near-critical region. However, the use of dry R236fa or isentropic R142b in NORC can be accepted because of the small superheat degree. The results also indicate that a small variation of evaporation temperature requires a large variation of expander inlet pressure, which may make the system more stable. In addition, due to the large decrease of latent heat in near-critical region, the variation of specific absorbed heat with evaporation temperature is small for NORC. Both specific net power and thermal efficiency for the fluids in NORC increase slightly with the rise of the evaporation temperature, especially for R236fa and R142b. Among the three types of fluids, dry R236fa and isentropic R142b are better suited for NORC. The results are useful for the design and optimization of ORC system in near-critical condition.

A new understanding on thermal efficiency of organic Rankine cycle: Cycle separation based on working fluids properties

2018 ◽  
Vol 157 ◽  
pp. 169-175 ◽  
Author(s):  
Yongzhen Wang ◽  
Jun Zhao ◽  
Guibing Chen ◽  
Shuai Deng ◽  
Qingsong An ◽  
...  
Keyword(s):  
Thermal Efficiency ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Working Fluids

Thermodynamic analysis of a wall mounted gas boiler with an organic Rankine cycle and hydrogen production unit

2017 ◽  
Vol 28 (7) ◽  
pp. 725-743 ◽  
Author(s):  
Anahita Moharamian ◽  
Saeed Soltani ◽  
Faramarz Ranjbar ◽  
Mortaza Yari ◽  
Marc A Rosen
Keyword(s):  
Hydrogen Production ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Inlet Pressure ◽  
Pinch Point ◽  
Working Fluids ◽  
Turbine Inlet ◽  
Energy And Exergy ◽  
Cogeneration System ◽  
Net Power Output

A novel cogeneration system based on a wall mounted gas boiler and an organic Rankine cycle with a hydrogen production unit is proposed and assessed based on energy and exergy analyses. The system is proposed in order to have cogenerational functionality and assessed for the first time. A theoretical research approach is used. The results indicate that the most appropriate organic working fluids for the organic Rankine cycle are HFE700 and isopentane. Utilizing these working fluids increases the energy efficiency of the integrated wall mounted gas boiler and organic Rankine cycle system by about 1% and the organic Rankine cycle net power output about 0.238 kW compared to when the systems are separate. Furthermore, increasing the turbine inlet pressure causes the net power output, the organic Rankine cycle energy and exergy efficiencies, and the cogeneration system exergy efficiency to rise. The organic Rankine cycle turbine inlet pressure has a negligible effect on the organic Rankine cycle mass flow rate. Increasing the pinch point temperature decreases the organic Rankine cycle turbine net output power. Finally, increasing the turbine inlet pressure causes the hydrogen production rate to increase; the highest and lowest hydrogen production rates are observed for the working fluids for HFE7000 and isobutane, respectively. Increasing the pinch point temperature decreases the hydrogen production rate. In the cogeneration system, the highest exergy destruction rate is exhibited by the wall mounted gas boiler, followed by the organic Rankine cycle evaporator, the organic Rankine cycle turbine, the organic Rankine cycle condenser, the proton exchange membrane electrolyzer, and the organic Rankine cycle pump, respectively.

scholarly journals Multi-Objective Optimization of Organic Rankine Cycle for Low-Grade Waste Heat Recovery

2019 ◽  
Vol 118 ◽  
pp. 03053
Author(s):  
Ruijie Wang ◽  
Jingquan Zhao ◽  
Lei Zhu ◽  
Guohua Kuang
Keyword(s):  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Exergy Efficiency ◽  
Condensation Temperature ◽  
Low Grade ◽  
Multi Objective Optimization ◽  
Working Fluids ◽  
Multi Objective ◽  
Evaporation Temperature

The organic Rankine cycle (ORC) is considered as one of the most viable technology to recover low-grade waste heat. A multi-objective optimization model is established to simultaneously derive the maximum exergy efficiency and the minimum electricity production cost (EPC) of a specific ORC system by employing the genetic algorithm (GA). Evaporation temperature and condensation temperature are selected as decision variables. At first, variations of exergy efficiency and EPC with evaporation temperature and condensation temperature are investigated respectively using R245fa, R245ca, R600, R600a, R601 and R601a as working fluids. Subsequently, a multi-objective optimization is performed and the Pareto frontiers for various working fluids are obtained. Results indicate that performance of the specific ORC system with R245fa as working fluid is better that with other working fluids.

The optimal evaporation temperature and working fluids for subcritical organic Rankine cycle

Energy ◽  
2012 ◽  
Vol 38 (1) ◽  
pp. 136-143 ◽  
Author(s):  
Chao He ◽  
Chao Liu ◽  
Hong Gao ◽  
Hui Xie ◽  
Yourong Li ◽  
...  
Keyword(s):  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Working Fluids ◽  
Evaporation Temperature

Analysis of Cogeneration System in Series Circuit Based on Regenerative Organic Rankine Cycle

2012 ◽  
Vol 505 ◽  
pp. 519-523 ◽  
Author(s):  
Kyoung Hoon Kim ◽  
Hyung Jong Ko ◽  
Se Woong Kim
Keyword(s):  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Inlet Pressure ◽  
Working Fluid ◽  
Combined System ◽  
Working Fluids ◽  
Source Temperature ◽  
Turbine Inlet ◽  
Cogeneration System ◽  
In Series

In this paper thermodynamic performance of a combined heat and power cogeneration system driven by low-temperature source is investigated. The system consists of regenerative Organic Rankine Cycle (ORC) and an additional process heater as a series circuit. Seven working fluids of isobutene, butane, R11, R123, isopentane, normal pentane, and R113 are considered in this work. Special attention is paid to the effects of system parameters such as the turbine inlet pressure or source temperature on the characteristics of the system such as the ratio of mass flow rates, net work production as well as the efficiencies of the first and second laws of thermodynamics for various working fluids. This study finds that higher turbine inlet pressure leads to lower second law efficiency of ORC system but higher that of the combined system. Results also show that the optimum working fluid varies with the source temperature.

scholarly journals Influence of working fluid evaporation temperature in the near-critical point region on the effectiveness of ORC power plant operation

2012 ◽  
Vol 33 (3) ◽  
pp. 73-83 ◽  
Author(s):  
Władysław Nowak ◽  
Aleksandra Borsukiewicz-Gozdur ◽  
Sławomir Wiśniewski
Keyword(s):  
Critical Point ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Maximum Power ◽  
Critical Conditions ◽  
Working Fluid ◽  
Working Fluids ◽  
Evaporation Temperature ◽  
Evaporation Enthalpy ◽  
Selection Of

Abstract In the paper presented are definitions of specific indicators of power which characterize the operation of the organic Rankine cycle (ORC) plant. These quantities have been presented as function of evaporation temperature for selected working fluids of ORC installation. In the paper presented also is the procedure for selection of working fluid with the view of obtaining maximum power. In the procedure of selection of working fluid the mentioned above indicators are of primary importance. In order to obtain maximum power there ought to be selected such working fluids which evaporate close to critical conditions. The value of this indicator increases when evaporation enthalpy decreases and it is known that the latent heat of evaporation decreases with temperature and reaches a value of zero at the critical point.

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