Working fluid selection of low grade heat geothermal Organic Rankine Cycle (ORC)

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.

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

Volume 3: Coal, Biomass and Alternative Fuels; Cycle Innovations; Electric Power; Industrial and Cogeneration Applications; Organic Rankine Cycle Power Systems ◽

10.1115/gt2017-63164 ◽

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.

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

Applied Sciences ◽

10.3390/app10103617 ◽

2020 ◽

Vol 10 (10) ◽

pp. 3617 ◽

Cited By ~ 1

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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Organic Rankine Cycle Simulation Based on Aspen Plus

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1070-1072.1808 ◽

2014 ◽

Vol 1070-1072 ◽

pp. 1808-1811 ◽

Cited By ~ 1

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.

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Parametric study and working fluid selection of the parallel type organic Rankine cycle and ejector heat pump combined cycle

Solar Energy ◽

10.1016/j.solener.2020.05.099 ◽

2020 ◽

Vol 205 ◽

pp. 487-495 ◽

Cited By ~ 1

Author(s):

Chenghu Zhang ◽

Jiyou Lin ◽

Yufei Tan

Keyword(s):

Heat Pump ◽

Parametric Study ◽

Organic Rankine Cycle ◽

Rankine Cycle ◽

Combined Cycle ◽

Working Fluid ◽

Working Fluid Selection ◽

Selection Of ◽

Parallel Type

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Study of working fluid selection of organic Rankine cycle (ORC) for engine waste heat recovery

Energy ◽

10.1016/j.energy.2011.03.041 ◽

2011 ◽

Vol 36 (5) ◽

pp. 3406-3418 ◽

Cited By ~ 416

Author(s):

E.H. Wang ◽

H.G. Zhang ◽

B.Y. Fan ◽

M.G. Ouyang ◽

Y. Zhao ◽

...

Keyword(s):

Heat Recovery ◽

Waste Heat Recovery ◽

Waste Heat ◽

Organic Rankine Cycle ◽

Rankine Cycle ◽

Working Fluid ◽

Working Fluid Selection ◽

Selection Of

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

E3S Web of Conferences ◽

10.1051/e3sconf/20186406004 ◽

2018 ◽

Vol 64 ◽

pp. 06004 ◽

Cited By ~ 1

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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