scholarly journals Preliminary Design of an Axial-Flow Turbine for Small-Scale Supercritical Organic Rankine Cycle

Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5277
Author(s):  
Ningjian Peng ◽  
Enhua Wang ◽  
Hongguang Zhang
Keyword(s):  
High Efficiency ◽  
Pressure Ratio ◽  
Organic Rankine Cycle ◽  
Axial Flow ◽  
Rankine Cycle ◽  
Tip Clearance ◽  
Small Scale ◽  
Preliminary Design ◽  
Trailing Edge ◽  
Turbine Efficiency

A small-scale organic Rankine cycle (ORC) with kW-class power output has a wide application prospect in industrial low-grade energy utilization. Increasing the expansion pressure ratio of small-scale ORC is an effective approach to improve the energy efficiency. However, there is a lack of suitable expander for small-scale ORC that can operate with a high efficiency under the condition of large expansion pressure ratio and small mass flow rate. Aiming at the design of high-efficiency axial-flow turbine in small ORC system, this paper investigates the performance of a kW-class axial-flow turbine and proposes a method for efficiency improvement. First, the preliminary design of an axial-flow turbine is conducted to optimize the geometric parameters and aerodynamic parameters. Then, the effects of tip clearance and trailing edge thickness on turbine performance are analyzed under design and off-design conditions. The results show that the efficiency of the two-stage or three-stage turbine is evidently better than that of the single-stage one. The output power and efficiency of the three-stage turbine are close to that of the two-stage turbine while the speed is lower. Meanwhile, the trailing edge loss and leakage loss can be significantly reduced via reducing the trailing edge thickness and tip clearance, and thus the turbine efficiency can be improved significantly. The estimated efficiency arrives at 0.82, which is 33% higher than that of the conventional turbine. Considering the limitation of turbine speed, three-stage axial-flow turbine is a feasible choice to improve turbine efficiency in a small-scale ORC.

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.

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.

scholarly journals REVIEW OF ORGANIC RANKINE CYCLE USED IN SMALL- SCALE APPLICATION

2020 ◽  
Vol 7 (1) ◽  
pp. 52-63
Author(s):  
Ali A. F. Al-Hamadani ◽  
Aya Haitham. A. Kareem
Keyword(s):  
Heat Exchanger ◽  
High Efficiency ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Small Scale ◽  
Heat Sources ◽  
Radial Turbine ◽  
Temperature Method ◽  
Energy From Waste

Organic Rankine cycle an alternative way of generating energy from waste heat, fuel and gases at low-temperature. Method (ORC) proved successful and high efficiency to reduce environmental pollution, fuel consumption and convert low to medium heat sources. The paper will be presenting a review investigation on the organic Rankine cycle(ORC), cycle Background, (ORC) configuration, and selecting of working fluids and experimental studied of expansion apparatuses, which are classified into two type volumetric type such as (expander of rotary vane, scroll, reciprocating piston expander and screw) velocity kind (for example axial and radial turbine). Heat exchanger and expander apparatuses are considered economically expensive parts in (ORC).

The Role of Dense Gas Dynamics on Organic Rankine Cycle Turbine Performance

2013 ◽  
Vol 135 (10) ◽  
Author(s):  
Andrew P. S. Wheeler ◽  
Jonathan Ong
Keyword(s):  
Pressure Ratio ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Navier Stokes ◽  
Working Fluid ◽  
Gas Flows ◽  
High Pressure Ratio ◽  
Dense Gases ◽  
Turbine Efficiency ◽  
Turbine Vanes

In this paper, we investigate the real gas flows which occur within organic Rankine cycle (ORC) turbines. A new method for the design of nozzles operating with dense gases is discussed, and applied to the case of a high pressure ratio turbine vane. A Navier–Stokes method, which uses equations of states for a variety of working fluids typical of ORC turbines, is then applied to the turbine vanes to determine the vane performance. The results suggest that the choice of working fluid has a significant influence on the turbine efficiency.

scholarly journals Performance Analysis of Organic Rankine Cycle with the Turbine Embedded in a Generator (TEG)

Energies ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 309
Author(s):  
Jung-Bo Sim ◽  
Se-Jin Yook ◽  
Young Won Kim
Keyword(s):  
Thermal Efficiency ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Turbine Rotor ◽  
Loss Coefficient ◽  
Tip Clearance ◽  
Working Fluid ◽  
Turbine Generator ◽  
Turbine Efficiency ◽  
Isentropic Efficiency

The organic Rankine cycle (ORC) is a thermodynamic cycle in which electrical power is generated using an organic refrigerant as a working fluid at low temperatures with low-grade enthalpy. We propose a turbine embedded in a generator (TEG), wherein the turbine rotor is embedded inside the generator rotor, thus simplifying turbine generator structure using only one bearing. The absence of tip clearance between the turbine rotor blade and casing wall in the TEG eliminates tip clearance loss, enhancing turbine efficiency. A single-stage axial-flow turbine was designed using mean-line analysis based on physical properties, and we conducted a parametric study of turbine performance, and predicted turbine efficiency and power using the tip clearance loss coefficient. When the tip clearance loss coefficient was applied, turbine isentropic efficiency and power were 0.89 and 20.42 kW, respectively, and ORC thermal efficiency was 4.81%. Conversely, the isentropic efficiency and power of the turbine without the tip clearance loss coefficient were 0.94 and 22.03 kW, respectively, and the thermal efficiency of the ORC was 5.08%. Therefore, applying the proposed TEG to the ORC system simplifies the turbine generator, while improving ORC thermal efficiency. A 3D turbine generator assembly with proposed TEG structure was also proposed.

scholarly journals A Theoretical and Experimental Study of HFE-7000 in a Small Scale Solar Organic Rankine Cycle As a Thermofluid

2017 ◽  
Author(s):  
Huseyin Utku Helvaci ◽  
Zulfiqar Ahmad Khan
Keyword(s):  
Renewable Energy ◽  
Flat Plate ◽  
Thermal Energy ◽  
Pressure Ratio ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Heat Energy ◽  
Small Scale ◽  
Low Grade ◽  
Solar Collectors

Renewable energy technologies and sources have been playing a key role in reducing CO2 emissions and its footprint. Solar energy which is one of the major renewable energy sources can be utilized by means of solar Photovoltaic (PV) or solar collectors. Concentrating solar collectors supply thermal energy from medium to high grade where as non-concentrating collectors (flat plate) delivers low-grade thermal energy. The use of thermofluids with boiling temperatures lower than water, allows the operation of low grade solar thermal systems on an Organic Rankine Cycle (ORC) to generate both mechanical and heat energy. At the same time, the selection of an appropriate thermofluid is an important process and has a significant effect both on the system performance and the environment. Hydrofluoroethers (HFEs) are non-ozone depleting substances and they have relatively low global warming potential (GWP). In this study, a solar ORC is designed and commissioned to use HFE 7000 as a thermofluid. The proposed system consists of a flat-plate solar collector, a vane expander, a condenser and a pump where the collector and the expander are used as the heat source and prime mover of the cycle respectively. The performance of the system is determined through energy analysis. Then, a mathematical model of the cycle is developed to perform the simulations using HFE-7000 at various expander pressure values. Experimental data indicates that the efficiency and the net mechanical work output of the cycle were found to be 3.81% and 135.96 W respectively. The simulation results show that increasing the pressure ratio of the cycle decreased the amount of the heat that is transferred to HFE 7000 in the collector due to the increased heat loss from the collector to the environment. Furthermore, the net output of the system followed a linear augmentation as the pressure ratio of the system increased. In conclusion, both the experimental and theoretical research indicates that HFE 7000 offers a viable alternative to be used efficiently in small scale solar ORCs to generate mechanical and heat energy.

Design of Small-Scale Radial Inflow Turbine Integrated into Organic Rankine Cycle

2012 ◽  
Vol 524-527 ◽  
pp. 3907-3913
Author(s):  
Hui Wang ◽  
Xin Ling Ma ◽  
Xin Li Wei
Keyword(s):  
Low Temperature ◽  
Flow Field ◽  
Simple Structure ◽  
High Efficiency ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
3D Models ◽  
Small Scale ◽  
Radial Inflow Turbine

Organic Rankine Cycle (ORC) is dramatically suitable for low temperature waste-heat generation. The small-scale radial inflow turbine is introduced to integrate into the ORC characterized by simple structure, low parts count, high efficiency, especially getting high efficiency under the condition of smaller flow. This turbine is comprised of four main parts named by the volute, the nozzle (stator), the impeller (rotor), and the diffuser respectively. This paper introduces how to design and model the parts in detail, discusses modeling skills and shares experience. The structure of the volute and impeller is so complicated that parts are not easy to model. These 3D models can directly import to both ANSYS and FLUENT to analysis the flow field in order to achieve the optimize parameters.

The Role of Dense Gas Dynamics on ORC Turbine Performance

2013 ◽  
Author(s):  
Andrew P. S. Wheeler ◽  
Jonathan Ong
Keyword(s):  
Pressure Ratio ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Navier Stokes ◽  
Working Fluid ◽  
Gas Flows ◽  
High Pressure Ratio ◽  
Dense Gases ◽  
Turbine Efficiency ◽  
Turbine Vanes

In this paper we investigate the real gas flows which occur within Organic Rankine Cycle (ORC) turbines. A new method for the design of nozzles operating with dense gases is discussed, and applied to the case of a high pressure ratio turbine vane. A Navier-Stokes method which uses equations of states for a variety of working fluids typical of ORC turbines is then applied to the turbine vanes to determine the vane performance. The results suggest that the choice of working fluid has a significant influence on the turbine efficiency.

scholarly journals Comparative investigation of working fluids for an organic Rankine cycle with geothermal water

2015 ◽  
Vol 36 (2) ◽  
pp. 75-84
Author(s):  
Yan-Na Liu ◽  
Song Xiao
Keyword(s):  
Power Generation ◽  
Pressure Ratio ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Comparative Investigation ◽  
Geothermal Water ◽  
Thermodynamic Investigation ◽  
Working Fluids ◽  
Temperature Heat ◽  
Input Pressure

AbstractIn this paper, the thermodynamic investigation on the use of geothermal water (130 °C as maximum) for power generation through a basic Rankine has been presented together with obtained main results. Six typical organic working fluids (i.e., R245fa, R141b, R290, R600, R152a, and 134a) were studied with modifying the input pressure and temperature to the turbine. The results show that there are no significant changes taking place in the efficiency for these working fluids with overheating the inlet fluid to the turbine, i.e., efficiency is a weak function of temperature. However, with the increasing of pressure ratio in the turbine, the efficiency rises more sharply. The technical viability is shown of implementing this type of process for recovering low temperature heat resource.

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