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.

Investigations on experimental performance and system behavior of 10 kW organic Rankine cycle using scroll-type expander for low-grade heat source

Energy ◽  
2019 ◽  
Vol 177 ◽  
pp. 94-105 ◽  
Author(s):  
Chih-Hung Lin ◽  
Pei-Pei Hsu ◽  
Ya-Ling He ◽  
Yong Shuai ◽  
Tzu-Chen Hung ◽  
...  
Keyword(s):  
Heat Source ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Low Grade ◽  
System Behavior ◽  
Experimental Performance ◽  
Low Grade Heat

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.

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.

Organic Rankine Cycle Simulation Based on Aspen Plus

2014 ◽  
Vol 1070-1072 ◽  
pp. 1808-1811 ◽  
Author(s):  
Han Lv ◽  
Wei Ting Jiang ◽  
Qun Zhi Zhu
Keyword(s):  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Aspen Plus ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Low Grade ◽  
Evaporation Temperature ◽  
Cycle Simulation ◽  
Simulation Based ◽  
Low Grade Heat

Organic Rankine cycle is an effective way to recover low-grade heat energy. In order to improve system performance, for low-temperature waste heat of 120°C and R245fa,R600a,R227ea organic working fluid, using Aspen Plus software conducted simulation by changing the evaporation temperature. Results from these analyses show that decreasing the evaporation temperature, increasing thermal and exergy efficiencies, evaporating pressure, at the same time reduce steam consumption rate.

A Computer Program for Working Fluid Selection of Low Temperature Organic Rankine Cycle

2015 ◽  
Author(s):  
Muhammad Ansab Ali ◽  
Tariq Saeed Khan ◽  
Ebrahim Al Hajri ◽  
Zahid H. Ayub
Keyword(s):  
Low Temperature ◽  
Heat Source ◽  
Computer Program ◽  
Fossil Fuels ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Power Production ◽  
Working Fluid ◽  
Low Grade

Fossil fuels are continuously depleting while the global energy demand is growing at a fast rate. Additionally, fossil fuels based power plants contribute to environmental pollution. Search for alternate energy resources and use of industrial waste heat for power production are attractive topics of interest these days. One way of enhancing power production and decreasing the environmental impact is by recuperating and utilizing low grade thermal energy. In recent years, research on use of organic Rankine cycle (ORC) has gained popularity as a promising technology for conversion of heat into useful work or electricity. Due to simple structure of ORC system, it can be easily integrated with any energy source like geothermal energy, solar energy and waste heat. A computer program has been developed in engineering equation solver (EES) environment that analyzes and selects appropriate working fluid for organic Rankine cycle design based on available heat sources. For a given heat source, the program compares energy and exergy performance of various working fluids. The program also includes recuperator performance analysis and compares its effectiveness on the overall thermal performance of the Rankine cycle. This program can assist in preliminary design of ORC with respect to best performing refrigerant fluid selection for the given low temperature heat source.

scholarly journals Prospects of Trilateral Flash Cycle (TFC) for Power Generation from Low Grade Heat Sources

2018 ◽  
Vol 64 ◽  
pp. 06004 ◽  
Author(s):  
Iqbal Md Arbab ◽  
Rana Sohel ◽  
Ahmadi Mahdi ◽  
Close Thomas ◽  
Date Abhijit ◽  
...  
Keyword(s):  
Power Generation ◽  
Organic Rankine Cycle ◽  
Thermodynamic Cycle ◽  
Cost Effective ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Low Grade ◽  
Power Stations ◽  
Expansion Stage ◽  
Low Grade Heat

Despite the current energy crisis, a large amount of low grade heat (below 100oC) is being wasted for the lack of cost effective energy conversion technology. In the case of the conventional Organic Rankine Cycle (ORC) based geothermal power stations, only about 20% of available heat can be utilised due to a technological limitation as there is a phase change in the working fluid involved during the addition of heat which decreases utilisation effectiveness of the system. Therefore, in this paper, a trilateral flash cycle (TFC) based system has been studied to find out its prospect for utilizing more power from the same heat resources as the ORC. The TFC is a thermodynamic cycle that heats the working fluid as a saturated liquid from which it starts its expansion stage. The flash expansion is achieved by feeding the saturated high-pressured liquid working fluid through a convergent-divergent nozzle at which point it undergoes a flash expansion in the low-pressure environment of the generator housing. The momentum of the working fluid is extracted via a Pelton wheel and the cycle is completed with working fluid condensation and pressurisation. The analytical comparative study between the ORC and TFC based system shows that the TFC has about 50% more power generation capability and almost zero contribution on global warming.

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