Design and Flow Analysis of a Supersonic Small Scale ORC Turbine Stator With High Molecular Complexity Working Fluid

2014 ◽  
Author(s):  
Antti Uusitalo ◽  
Teemu Turunen-Saaresti ◽  
Alberto Guardone ◽  
Aki Grönman
Keyword(s):  
High Efficiency ◽  
Waste Heat ◽  
Flow Analysis ◽  
Organic Rankine Cycle ◽  
Working Fluid ◽  
Small Scale ◽  
Low Grade ◽  
Real Gas ◽  
Turbine Stator ◽  
Molecular Complexity

In small scale and low temperature waste heat recovery systems, Organic Rankine Cycle (ORC) technology can be identified as a promising solution in converting low-grade heat into electricity. The principle of ORC is based on a conventional Rankine process but an organic working fluid is adopted instead of steam. The use of high molecular complexity working fluids enables the design of high efficiency ORCs and are characterized by dry expansion and high pressure ratios over the turbine, as well as low speed of sound, which typically leads to highly supersonic flows in the ORC turbine stator. In order to design supersonic ORC turbines, the geometry of the turbine stator has to be based on design methods that accurately take into account the real gas effects of the working fluid during the expansion. In this study, a highly supersonic small scale ORC turbine stator using siloxane MDM as working fluid, is studied. The accurate real gas model was implemented in a CFD-flow solver in order to predict the flow field in the stator in design and in off-design conditions. The results of this study gives valuable information on realising small capacity ORC turbomachinery, characterized by highly supersonic stators, and on the off-design performance of supersonic radial turbine stator that has not been documented or discussed in the previous studies.

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.

Thermo-economic optimization of small-scale Organic Rankine Cycle: A case study for low-grade industrial waste heat recovery

Energy ◽  
2020 ◽  
Vol 213 ◽  
pp. 118898
Author(s):  
Bernardo Peris ◽  
Joaquín Navarro-Esbrí ◽  
Carlos Mateu-Royo ◽  
Adrián Mota-Babiloni ◽  
Francisco Molés ◽  
...  
Keyword(s):  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Small Scale ◽  
Low Grade ◽  
Economic Optimization ◽  
Industrial Waste Heat

Performance Evaluation of a Small Scale High Efficiency Cogeneration System

2006 ◽  
Author(s):  
Mauro Reini
Keyword(s):  
High Efficiency ◽  
Pressure Ratio ◽  
Organic Rankine Cycle ◽  
Thermodynamic Cycle ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Working Fluid ◽  
Small Scale ◽  
Performance Parameters ◽  
Cogeneration System

In recent years, a big effort has been made to improve microturbines thermal efficiency, in order to approach 40%. Two main options may be considered: i) a wide usage of advanced materials for hot ends components, like impeller and recuperator; ii) implementing more complicated thermodynamic cycle, like combined cycle. In the frame of the second option, the paper deals with the hypothesis of bottoming a low pressure ratio, recuperated gas cycle, typically realized in actual microturbines, with an Organic Rankine Cycle (ORC). The object is to evaluate the expected nominal performance parameters of the integrated-combined cycle cogeneration system, taking account of different options for working fluid, vapor pressure and component’s performance parameters. Both options of recuperated and not recuperated bottom cycles are discussed, in relation with ORC working fluid nature and possible stack temperature for microturbine exhaust gases. Finally, some preliminary consideration about the arrangement of the combined cycle unit, and the effects of possible future progress of gas cycle microturbines are presented.

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.

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.

Experimental Investigation of a Small-Scale Orc Turbo-Generator Supported On Gas-Lubricated Bearings

2021 ◽  
Author(s):  
Kévin Rosset ◽  
Olivier Pajot ◽  
Jurg Schiffmann
Keyword(s):  
High Speed ◽  
Waste Heat ◽  
Electrical Power ◽  
Organic Rankine Cycle ◽  
Mechanical Efficiency ◽  
Load Level ◽  
Working Fluid ◽  
Small Scale ◽  
Electrical Machine ◽  
Turbo Generator

Abstract Waste heat recovery is expected to contribute to reducing CO2 emissions from trucks. Organic Rankine cycle (ORC) systems show the highest potential for this application, but still lack efficient small-scale expansion devices, in practice. A novel turbo-generator supported on gas-lubricated bearings is presented in this paper. The device combines a single-stage radial-inflow turbine and a permanent-magnet machine in a single rotating part supported on aerodynamic bearings, lubricated with the working fluid (R245fa). The oil-free expander was tested within a dedicated ORC test setup. It was driven up to its nominal speed of 100 kRPM, generated up to 2.3 kW of electrical power, and reached a peak overall efficiency of 67%. Although the prototype was not actively cooled, the mechanical losses of the rotor shaft and the iron loss of the electrical machine reached their nominal levels. Only the copper loss was at a part-load level. The electro-mechanical efficiency of the turbo-generator reached 91% and is expected to increase while testing the device at higher load. This proof of concept confirms the high-speed and low-loss potential of gas-lubricated bearings for small-scale dynamic expanders.

3D CFD Analysis of a Twin Screw Expander With Different Real Gas Models for R245fa

2015 ◽  
Author(s):  
Iva Papes ◽  
Lazhar Abdelli ◽  
Joris Degroote ◽  
Jan Vierendeels
Keyword(s):  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Primary Energy ◽  
Ideal Gas ◽  
Production Costs ◽  
Working Fluid ◽  
Real Gas ◽  
Twin Screw ◽  
The Ideal

With the increasing importance of minimizing primary energy usage and complying with emission restrictions, a significant interest has been developed towards waste heat recovery from industrial processes. A large portion of this energy is available at low temperatures (350K–400K) but it can be relatively efficiently converted into mechanical power using an Organic Rankine Cycle (ORC). Twin screw expanders can be used as an alternative to turbines with their cheap production costs and well proven efficiencies. In this paper, 3D CFD simulations of a twin screw expander using R245fa as the working fluid are performed. Since the fluid properties show big deviations when using the ideal gas equation of state (EoS), the flow problem has been evaluated using different real gas models. Thermodynamic parameters for the ideal gas EoS, the cubic Aungier Redlich-Kwong EoS and the CoolProp fluid database (open source) were compared in a preliminary study. After that, the models have been included through user-defined functions (UDFs) in ANSYS Fluent and were tested on 3D CFD calculations of a twin screw expander and a simplified expansion model. Several performance indicators such as mass flow rates, pressure-volume diagrams and power output are used to compare different fluid models for R245fa. From the results of this study, it can be concluded that the ideal gas EoS shows big deviations going closer to the saturation vapor line and the deviation in power comparing to the Aungier Redlich-Kwong EoS is around 8%. Conversely, the Aungier Redlich-Kwong EoS and the CoolProp database present very similar results for this case.

Sign in / Sign up

Export Citation Format

Share Document