Thermodynamic Analysis of Organic Rankine Cycle (ORC) Systems Based on Turbine Performance Prediction

2016 ◽  
Author(s):  
Jian Song ◽  
Chun-wei Gu
Keyword(s):  
System Analysis ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Parameter Determination ◽  
Working Fluid ◽  
Low Grade ◽  
One Dimensional ◽  
Turbine Efficiency ◽  
Turbine Performance ◽  
The One

Energy shortage and environmental deterioration are two crucial issues that the developing world must face. As a promising solution, the conversion of low grade energies is attracting more and more attention. Among all of the existing technologies, Organic Rankine Cycle (ORC) has been proven to be an effective method to utilize the low grade energies. Thermodynamic analysis is important for working fluid selection and system parameter determination in the ORC system. In conventional studies, the efficiency of the organic turbine is fixed at a constant value. However, the turbine efficiency is evidently related to the working fluid property and system operating condition. Thus, the constant turbine efficiency is unreasonable and may lead to sub-optimal thermal results. To enhance the reliability and accuracy of ORC system analysis, the one-dimensional analysis model is used to predict the turbine performance in this paper. The calculated one-dimensional turbine efficiency replaces the constant efficiency in the system analysis. The influence of the working fluid property and system operating condition on the turbine performance is evaluated. Thermal performances of the ORC systems with the one-dimensional turbine efficiency and the constant turbine efficiency are simulated and compared. The results reveal that the turbine efficiency plays a significant role in working fluid selection and system parameter determination for the ORC system.

1-D Model Analysis of Tesla Turbine for Small Scale Organic Rankine Cycle (ORC) System

2017 ◽  
Author(s):  
Jian Song ◽  
Chun-wei Gu
Keyword(s):  
Large Scale ◽  
Low Cost ◽  
Organic Rankine Cycle ◽  
Axial Flow ◽  
Rankine Cycle ◽  
Expansion Ratio ◽  
Working Fluid ◽  
Small Scale ◽  
Low Grade ◽  
D Model

Energy shortage and environmental deterioration are two crucial issues that the developing world has to face. In order to solve these problems, conversion of low grade energy is attracting broad attention. Among all of the existing technologies, Organic Rankine Cycle (ORC) has been proven to be one of the most effective methods for the utilization of low grade heat sources. Turbine is a key component in ORC system and it plays an important role in system performance. Traditional turbine expanders, the axial flow turbine and the radial inflow turbine are typically selected in large scale ORC systems. However, in small and micro scale systems, traditional turbine expanders are not suitable due to large flow loss and high rotation speed. In this case, Tesla turbine allows a low-cost and reliable design for the organic expander that could be an attractive option for small scale ORC systems. A 1-D model of Tesla turbine is presented in this paper, which mainly focuses on the flow characteristics and the momentum transfer. This study improves the 1-D model, taking the nozzle limit expansion ratio into consideration, which is related to the installation angle of the nozzle and the specific heat ratio of the working fluid. The improved model is used to analyze Tesla turbine performance and predict turbine efficiency. Thermodynamic analysis is conducted for a small scale ORC system. The simulation results reveal that the ORC system can generate a considerable net power output. Therefore, Tesla turbine can be regarded as a potential choice to be applied in small scale ORC systems.

scholarly journals Integrated Vapor Compression Chiller with Bottoming Organic Rankine Cycle and Onsite Low-Grade Renewable Energy

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6401
Author(s):  
Muhammad Tauseef Nasir ◽  
Michael Chukwuemeka Ekwonu ◽  
Javad Abolfazali Esfahani ◽  
Kyung Chun Kim
Keyword(s):  
Renewable Energy ◽  
Heat Source ◽  
Energy Input ◽  
Cooling Water ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Sensitivity Analyses ◽  
Working Fluid ◽  
Inlet Temperature ◽  
Low Grade

The present study offers a scheme to improve the performance of existing large-scale chillers. The system involves raising the temperature of the chiller’s cooling water stream using renewable energy sources by incorporating an organic Rankine cycle (ORC). The thermal analysis was conducted by raising the temperature of one-third of the approximately 200 ton chiller’s cooling water. The investigation was considered for ORC evaporator inlet temperature of 90~120 °C by the step of 10 °C. Various working fluids for the different ORC evaporator inlet temperatures were examined. Sensitivity analyses conducted on the degree of superheating, degree of subcooling, condenser saturation temperature, pinch point temperature differences of the ORC evaporator and condenser, and the mass flowrates of the heating and cooling streams were also reported. Genetic algorithm was employed to carry out the optimization. The best options for the ORC working fluid at the heating source ORC evaporator inlet temperatures of 90 °C was found to be DME, presenting an improvement of 48.72% in comparison with the rated coefficient of performance (COP) value of the VCC, with a renewable energy input requirement of 710 kW. At the heat source temperatures of 100 °C and 110 °C, butene, which presented an improvement in the COP equal to 48.76% and 68.85%, respectively, with the corresponding renewable energy requirements of 789.6 kW and 852 kW, was found to be the ideal candidate. Meanwhile, at the heat source inlet temperature of 120 °C, R1233zd (E), representing an improvement of 140.88% with the renewable energy input of around 1061 kW, was determined to be the most favorable ORC working fluid candidate.

scholarly journals Addressing Industrial Waste Heat Supply Variability With Organic Rankine Cycle Systems Incorporating Thermal Energy Storage

2021 ◽  
Author(s):  
Bipul Krishna Saha ◽  
Basab Chakraborty ◽  
Rohan Dutta
Keyword(s):  
Power Generation ◽  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Power Plants ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Low Grade

Abstract Industrial low-grade waste heat is lost, wasted and deposited in the atmosphere and is not put to any practical use. Different technologies are available to enable waste heat recovery, which can enhance system energy efficiency and reduce total energy consumption. Power plants are energy-intensive plants with low-grade waste heat. In the case of such plants, recovery of low-grade waste heat is gaining considerable interest. However, in such plants, power generation often varies based on market demand. Such variations may adversely influence any recovery system's performance and the economy, including the Organic Rankine Cycle (ORC). ORC technologies coupled with Cryogenic Energy Storage (CES) may be used for power generation by utilizing the waste heat from such power plants. The heat of compression in a CES may be stored in thermal energy storage systems and utilized in ORC or Regenerative ORC (RORC) for power generation during the system's discharge cycle. This may compensate for the variation of the waste heat from the power plant, and thereby, the ORC system may always work under-designed capacity. This paper presents the thermo-economic analysis of such an ORC system. In the analysis, a steady-state simulation of the ORC system has been developed in a commercial process simulator after validating the results with experimental data for a typical coke-oven plant. Forty-nine different working fluids were evaluated for power generation parameters, first law efficiencies, purchase equipment cost, and fixed investment payback period to identify the best working fluid.

Innovative Research in the Organic Rankine Cycle

Impact ◽  
2020 ◽  
Vol 2020 (6) ◽  
pp. 76-78
Author(s):  
Tzu-Chen Hung ◽  
Yong-Qiang Feng
Keyword(s):  
Phase Change ◽  
Mechanical Energy ◽  
Heat Engine ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Vapour Phase ◽  
Working Fluid ◽  
Low Grade ◽  
Initial State ◽  
Thermodynamic Cycles

Thermodynamic cycles consist of a sequence of thermodynamic processes involving the transfer of heat and work into and then out of a system. Variables, such as pressure and temperature, eventually return the system to its initial state. During the process of passing through the system, the working fluid converts heat and disposes of any remaining heat, making the cycle act as a heat engine, where heat or thermal energy is converted into mechanical energy. Thermodynamic cycles are an efficient means of producing energy and one of the most well-known examples is a Rankine cycle. From there, scientists have developed the organic Rankine cycle (ORC), which uses fluid with a liquid to vapour phase change that occurs at a lower temperature than the water to steam phase change. Dr Tzu-Chen Hung and Dr Yong-Qiang Feng, who are based at both the Department of Mechanical Engineering, National Taipei University in Taiwan, and the School of Energy and Power Engineering, Jiangsu University in China, are carrying out work that seeks to design and build improved ORC systems which can be used for low-grade heat to power conversion.

Performance Evaluation of a Turbine Used in a Regenerative Organic Rankine Cycle

2012 ◽  
Author(s):  
Maoqing Li ◽  
Jiangfeng Wang ◽  
Lin Gao ◽  
Xiaoqiang Niu ◽  
Yiping Dai
Keyword(s):  
Flow Rate ◽  
Rotational Speed ◽  
Electrical Power ◽  
Organic Rankine Cycle ◽  
Axial Flow ◽  
Rankine Cycle ◽  
Operating Conditions ◽  
Working Fluid ◽  
Low Grade ◽  
Low Grade Heat

Due to environmental constraints, the Organic Rankine Cycle (ORC) is widely used to generate electricity from low grade heat sources. In ORC processes, the working fluid is an organic substance, which has a better thermodynamic performance than water for low grade heat recovery. The design of the turbine which is the key component in the ORC system strongly depends on the operating conditions and on the scale of the facility. This paper presents an experimental study on a prototype of an axial-flow turbine integrated into a regenerative ORC system with R123 as working fluid. The power output is 10kW scale, and the single-stage turbine is selected. The turbine is specially designed and manufactured, and a generator is connected to the turbine directly. In the experiment, the turbine is tested under different inlet pressure conditions (0.6–1.5MPa), different inlet temperature conditions (80–150°C) and different flow rate conditions. The experimental data such as the pressures, temperatures of the turbine inlet and outlet, flow rate, rotational speed, and electrical power generation are analyzed to find their inner relationships. During the test, the turbine rotational speed could reach more than 3010 r/min, while the design rotational speed is 3000 r/min. The isentropic efficiency of the turbine could reach 53%. The maximum electrical power generated by the turbine-generator is 6.57KW. From the test data the peak value of the temperature difference between the inlet and the outlet of the turbine is 53 °C, and the expansion ratio reaches about 11. The computational fluid dynamics (CFD) solvers is also used to analyze the performance of the turbine. The distributions of the pressure, Mach number, and static entropy in the turbine flow passage component are examined and the reasons are also obtained. This study reveals the relationships between the performance of the axial-flow turbine and its inlet and outlet vapor conditions. The experiment results and the CFD results lay a foundation for using this type turbine in the ORC systems which product electrical power from a few KW to MW.

Working Fluid and Parametric Optimization of a Two-Stage ORC Utilizing LNG Cold Energy and Low Grade Heat of Different Temperatures

2017 ◽  
Author(s):  
Zhixin Sun ◽  
Shujia Wang ◽  
Fuquan Xu ◽  
Tielong Wang
Keyword(s):  
Heat Source ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Cycle Performance ◽  
Maximum Efficiency ◽  
Working Fluid ◽  
Low Grade ◽  
Two Stage ◽  
Cold Energy ◽  
Low Grade Heat

Natural gas is considered as a green fuel due to its low environmental impact. LNG contains a large amount of cold exergy and must be regasified before further utilization. ORC (Organic Rankine Cycle) has been proven to be a promising solution for both low grade heat utilization and LNG cold exergy recovery. Due to the great temperature difference between the heat source and LNG, the efficiency of one-stage ORC is relatively small. Hence, some researchers move forward to a two-stage Rankine cycle. Working fluid plays a quite important role in the cycle performance. Working fluid selection of a two-stage ORC is much more challenging than that of a single-stage ORC. In this paper, a two-stage ORC is studied. Heat source temperatures of 100,150 and 200°C are investigated. 20 substances are selected as potential candidates for both the high and low Rankine cycles. The evaporating, condensing and turbine inlet temperatures of both Rankine cycles are optimized by PSO (Particle Swarm Optimization). The results show that the best combination for heat source temperature of 100°C is R161/R218 with the maximum exergy efficiency of 35.27%. The best combination for 150°C is R161/RC318 with the maximum efficiency of 37.84% and ammonia/ammonia with the maximum efficiency of 39.15% for 200°C. Fluids with intermediate critical temperature, lower triple point temperature and lower normal boiling temperature are good candidates.

Design and Optimization of a Low Temperature Organic Rankine Cycle and Turbine

2013 ◽  
Author(s):  
Murat Erbas ◽  
Mehmet Alper Sofuoglu ◽  
Atilla Biyikoglu ◽  
Ibrahim Uslan
Keyword(s):  
Low Temperature ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Cycle Performance ◽  
Working Fluid ◽  
Design Criteria ◽  
Design And Optimization ◽  
Turbine Efficiency ◽  
Design Requirements ◽  
R 134A

In this study, low temperature Organic Rankine Cycle (ORC) systems with single and two-stage turbine are proposed for the production of electricity. The refrigerant R-134a is selected as working fluid based on peak temperature of the cycle for solar and geothermal applications. The design criteria of ORC system is introduced and explained in detail. The radial inflow turbine is selected to satisfy the design requirements. The cycle performance is taken as a key point in the design criteria. The system performance map is constructed based on both velocity triangles and approximate efficiency of turbine. The procedures for turbine and cycle design are introduced in detail. The components of cycle and turbine are modeled using baseline correlations via real gas tables and macros created on Excel for the refrigerant, R134a. Finally, the turbine geometry is optimized to attain maximum turbine efficiency via MATLAB optimization toolbox.

scholarly journals Conversion of Low-Grade Heat from Multiple Streams in Methanol to Olefin (MTO) Process Based on Organic Rankine Cycle (ORC)

2020 ◽  
Vol 10 (10) ◽  
pp. 3617 ◽  
Author(s):  
Danchen Wei ◽  
Cheng Liu ◽  
Zhongfeng Geng
Keyword(s):  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Exergy Efficiency ◽  
Working Fluid ◽  
Low Grade ◽  
Maximum Output ◽  
Methanol To Olefin ◽  
Thermodynamic Performance ◽  
Selection Of ◽  
Mto Process

The organic rankine cycle (ORC) has been widely used to convert low-grade thermal energy to electricity. The selection of the cycle configuration, working fluid, and operating parameters is crucial for the economic profitability of the ORC system. In the methanol to olefin (MTO) process, multi-stream low-temperature waste heat has not been effectively utilized. The previous study mostly focused on the optimization of a single stream system and rarely considered the comprehensive optimization of multi-stream ORC systems which have multi-temperature heat sources. This paper proposes five kinds of system design schemes, and determines the optimal output work and the highest exergy efficiency through the selection of working fluid and optimization of system parameters. In addition, the influence of mixed working fluid on the thermodynamic performance of the system was also investigated. It is found that there is an optimal evaporation temperature due to the restriction of pinch temperature. At the optimal temperature the ORC system obtains the maximum net output power of 4.95 MW. The optimization results show that the working fluid R227EA selected from seven candidate working fluids shows the optimal thermodynamic performance in all the five design schemes, and obtains the maximum output work and exergy efficiency.

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