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

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

10.21203/rs.3.rs-658624/v1 ◽

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.

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

Volume 6: Oil and Gas Applications; Concentrating Solar Power Plants; Steam Turbines; Wind Energy ◽

10.1115/gt2012-68441 ◽

2012 ◽

Cited By ~ 2

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.

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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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Situation Analysis of Organic Rankine Cycle System for Low-Grade Heat Power Generation in China

2011 Asia-Pacific Power and Energy Engineering Conference ◽

10.1109/appeec.2011.5748438 ◽

2011 ◽

Author(s):

Yongxi Liao ◽

Bin Xiong ◽

Hui Guo

Keyword(s):

Power Generation ◽

Organic Rankine Cycle ◽

Rankine Cycle ◽

Low Grade ◽

Heat Power ◽

Situation Analysis ◽

Cycle System ◽

Low Grade Heat

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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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The condensing engine: A heat engine for operating temperatures of 100 ℃ and below

Proceedings of the Institution of Mechanical Engineers Part A Journal of Power and Energy ◽

10.1177/0957650917736455 ◽

2017 ◽

Vol 232 (4) ◽

pp. 437-448

Author(s):

Gerald Müller ◽

Chun Ho Chan ◽

Alexander Gibby ◽

Muhammad Zubair Nazir ◽

James Paterson ◽

...

Keyword(s):

Heat Engine ◽

Organic Rankine Cycle ◽

Cost Effective ◽

Rankine Cycle ◽

Expansion Ratio ◽

Theoretical Development ◽

Working Fluid ◽

Low Grade ◽

The Difference ◽

Power Outputs

The cost-effective utilisation of low-grade thermal energy with temperatures below 150 ℃ for electricity generation still constitutes an engineering challenge. Existing technology, e.g. the organic Rankine cycle machines, are complex and only economical for larger power outputs. At Southampton University, the steam condensation cycle for a working temperature of 100 ℃ was analysed theoretically. The cycle uses water as working fluid, which has the advantages of being cheap, readily available, non-toxic, non-inflammable and non-corrosive, and works at and below atmospheric pressure, so that leakage and sealing are not problematic. Steam expansion will increase the theoretical efficiency of the cycle from 6.4% (no expansion) to 17.8% (expansion ratio 1:8). In this article, the theoretical development of the cycle is presented. A 40 Watt experimental engine was built and tested. Efficiencies ranged from 0.02 (no expansion) to 0.055 (expansion ratio 1:4). The difference between theoretical and experimental efficiencies was attributed to significant pressure loss in valves, and to difficulties with heat rejection. It was concluded that the condensing engine has potential for further development.

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Cost Effective Small Scale ORC Systems for Power Recovery From Low Grade Heat Sources

Advanced Energy Systems ◽

10.1115/imece2006-14284 ◽

2006 ◽

Cited By ~ 20

Author(s):

H. Leibowitz ◽

I. K. Smith ◽

N. Stosic

Keyword(s):

Organic Rankine Cycle ◽

Cost Effective ◽

Rankine Cycle ◽

Small Scale ◽

Low Grade ◽

Full Potential ◽

Heat Sources ◽

Capacity Cost ◽

Power Recovery ◽

Low Grade Heat

The growing need to recover power from low grade heat sources, has led to a review of the possibilities for producing systems for cost effective power production at outputs as little as 20-50kWe. It is shown that by utilizing the full potential of screw expanders instead of turbines, it is possible to produce Organic Rankine Cycle (ORC) systems at these outputs, which can be installed for a cost in the range of $1500 to $2000 /kWe of net output. This low capacity cost combined with the ORC's fuel-free specification results in a very favorable value proposition.

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