Meanline Analysis and CFD Study of a Radial Inflow Turbine With Vaneless Distributor for Low Temperature Organic Rankine Cycle

2020 ◽  
Author(s):  
M. Deligant ◽  
S. Braccio ◽  
T. Capurso ◽  
F. Fornarelli ◽  
M. Torresi ◽  
...  
Keyword(s):  
Energy Demand ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Operating Conditions ◽  
Low Grade ◽  
Heat Sources ◽  
Turbine Wheel ◽  
Good Efficiency ◽  
Low Grade Heat

Abstract The Organic Rankine Cycle (ORC) allows the conversion of low-grade heat sources into electricity. Although this technology is not new, the increase in energy demand and the need to reduce CO2 emissions create new opportunities to harvest low grade heat sources such as waste heat. Radial turbines have a simple construction, they are robust and they are not very sensitive to geometry inaccuracies. Most of the radial inflow turbines used for ORC application feature a vaned nozzle ensuring the appropriate distribution angle at the rotor inlet. In this work, no nozzle is considered but only the vaneless gap (distributor). This configuration, without any vaned nozzle, is supposed to be more flexible under varying operating conditions with respect to fixed vanes and to maintain a good efficiency at off-design. This paper presents a performance analysis carried out by means of two approaches: a combination of meanline loss models enhanced with real gas fluid properties and 3D CFD computations, taking into account the entire turbomachine including the scroll housing, the vaneless gap, the turbine wheel and the axial discharge pipe. A detailed analysis of the flow field through the turbomachine is carried out, both under design and off design conditions, with a particular focus on the entropy field in order to evaluate the loss distribution between the scroll housing, the vaneless gap and the turbine wheel.

Second Law Analysis and Optimization of Organic Rankine Cycle

2006 ◽  
Author(s):  
C. Somayaji ◽  
P. J. Mago ◽  
L. M. Chamra
Keyword(s):  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Operating Conditions ◽  
Working Fluid ◽  
Second Law ◽  
Low Grade ◽  
Heat Sources ◽  
Working Fluids ◽  
Second Law Analysis

This paper presents a second law analysis and optimization for the use of Organic Rankine Cycle “ORC” to convert waste energy to power from low grade heat sources. The working fluids used in this study are organic substances which have a low boiling point and a low latent heat for using low grade waste heat sources. The organic working fluids under investigation are R134a and R113 and their results are compared with those of ammonia and water under similar operating conditions. A combined first and second law analysis is performed by varying some system operating parameters at various reference temperatures. Some of the results show that the efficiency of ORC is typically below 20% depending on the temperatures and matched working fluid. In addition, it has been found that organic working fluids are more suited for heat recovery than water for low temperature applications, which justifies the use of organic working fluids at the lower waste source temperatures.

Supercritical Fluids and Their Applications in Power Generation

2021 ◽  
pp. 566-599
Author(s):  
Huijuan Chen ◽  
Ricardo Vasquez Padilla ◽  
Saeb Besarati
Keyword(s):  
Power Generation ◽  
Supercritical Fluids ◽  
Waste Heat ◽  
Electrical Power ◽  
Rankine Cycle ◽  
Low Grade ◽  
Heat Sources ◽  
Working Fluids ◽  
Low Grade Heat ◽  
Selection Of

Supercritical fluids have been studied and used as the working fluids in power generation system for both high- and low-grade heat conversions. Low-grade heat sources, typically defined as below 300 ºC, are abundantly available as industrial waste heat, solar thermal, and geothermal, to name a few. However, they are under-exploited for power conversion because of the low conversion efficiency. Technologies that allow the efficient conversion of low-grade heat into mechanical or electrical power are very important to develop. First part of this chapter investigates the potential of supercritical Rankine cycles in the conversion of low-grade heat to power, while the second part discusses supercritical fluids used in higher grade heat conversion system. The selection of supercritical working fluids for a supercritical Rankine cycle is of key importance. This chapter discusses supercritical fluids fundamentals, selection of supercritical working fluids for different heat sources, and the current research, development, and commercial status of supercritical power generation systems.

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.

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

2006 ◽  
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.

scholarly journals Experimental characterization of an ORC (organic Rankine cycle) for power and CHP (combined heat and power) applications from low grade heat sources

Energy ◽  
2015 ◽  
Vol 82 ◽  
pp. 269-276 ◽  
Author(s):  
Bernardo Peris ◽  
Joaquín Navarro-Esbrí ◽  
Francisco Molés ◽  
Manuel González ◽  
Adrián Mota-Babiloni
Keyword(s):  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Combined Heat And Power ◽  
Low Grade ◽  
Heat Sources ◽  
Experimental Characterization ◽  
Low Grade Heat

scholarly journals Thermodynamic investigation of organic Rankine cycle energy recovery system and recent studies

2018 ◽  
Vol 22 (6 Part A) ◽  
pp. 2679-2690 ◽  
Author(s):  
Ozlem Boydak ◽  
Ismail Ekmekci ◽  
Mustafa Yilmaz ◽  
Hasan Koten
Keyword(s):  
Phase Change ◽  
Low Temperatures ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Energy Resources ◽  
Working Fluid ◽  
Low Grade ◽  
Heat Sources ◽  
Water Steam ◽  
Low Grade Heat

Recently, new environment-friendly energy conversion technologies are required for using energy resources valid to power generation. Accordingly, low-grade heat sources as solar heat, geothermal energy, and waste heat, which have available temperatures ranging between 60 and 200?C, are supposed as applicants for recent new generation energy resources. As an alternative energy source, such low-grade heat sources usage generating electricity with the help of power turbine cycles was examined through this study. Such systems have existing technologies applicable at low temperatures and a compact structure at low cost, however, these systems have a low thermal efficiency of the Rankine cycles operated at low temperatures. An organic Rankine cycle is alike to a conventional steam power plant, except the working fluid, which is an organic, high molecular mass fluid with a liquid-vapor phase change, or boiling point, at a lower temperature than the water-steam phase change. The efficiency of an organic Rankine cycle is about between 10% and 20%, depending on temperature levels and availability of a valid fluid.

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