scholarly journals 3D CFD Simulations of a Candidate R143A Radial-Inflow Turbine for Geothermal Power Applications

2014 ◽  
Author(s):  
Emilie Sauret ◽  
Yuantong Gu
Keyword(s):  
Numerical Simulations ◽  
Equations Of State ◽  
Thermodynamic Cycle ◽  
High Density ◽  
Operating Conditions ◽  
Working Fluid ◽  
Cfd Simulations ◽  
Binary Cycle ◽  
Radial Inflow Turbine ◽  
Turbine Design

Optimisation of Organic Rankine Cycles (ORCs) for binary cycle applications could play a major role in determining the competitiveness of low to moderate renewable sources. An important aspect of the optimisation is to maximise the turbine output power for a given resource. This requires careful attention to the turbine design notably through numerical simulations. Challenges in the numerical modelling of radial-inflow turbines using high-density working fluids still need to be addressed in order to improve the turbine design and better optimise ORCs. This paper presents preliminary 3D numerical simulations of a radial-inflow turbine working with high-density fluids in realistic geothermal ORCs. Following extensive investigation of the operating conditions and thermodynamic cycle analysis, the refrigerant R143a is chosen as the high-density working fluid. The 1D design of the candidate radial-inflow turbine is presented in details. Furthermore, commercially-available software Ansys-CFX is used to perform preliminary steady-state 3D CFD simulations of the candidate R143a radial-inflow turbine at the nominal operating condition. The real-gas properties are obtained using the Peng-Robinson equations of state. The thermodynamic ORC cycle is presented. The preliminary design created using dedicated radial-inflow turbine software Concepts-Rital is discussed and the 3D CFD results are presented and compared against the meanline analysis.

Novel Combined Power and Cooling Thermodynamic Cycle for Low Temperature Heat Sources, Part II: Experimental Investigation

2003 ◽  
Vol 125 (2) ◽  
pp. 223-229 ◽  
Author(s):  
Gunnar Tamm ◽  
D. Yogi Goswami
Keyword(s):  
Low Temperature ◽  
System Analysis ◽  
Waste Heat ◽  
Thermal Power ◽  
Experimental System ◽  
Thermodynamic Cycle ◽  
Operating Conditions ◽  
Working Fluid ◽  
Water Mixture ◽  
Theoretical Simulation

A combined thermal power and cooling cycle proposed by Goswami is under intensive investigation, both theoretically and experimentally. The proposed cycle combines the Rankine and absorption refrigeration cycles, producing refrigeration while power is the primary goal. A binary ammonia-water mixture is used as the working fluid. This cycle can be used as a bottoming cycle using waste heat from a conventional power cycle or as an independent cycle using low temperature sources such as geothermal and solar energy. An experimental system was constructed to demonstrate the feasibility of the cycle and to compare the experimental results with the theoretical simulation. Results showed that the vapor generation and absorption condensation processes work experimentally, exhibiting expected trends, but with deviations from ideal and equilibrium modeling. The potential for combined turbine work and refrigeration output was evidenced in operating the system. Analysis of losses showed where improvements could be made, in preparation for further testing over a broader range of operating conditions.

scholarly journals Utilization Waste Brine Water Separator for Binary Electric Energy Conversion in Geothermal Wells

2021 ◽  
Vol 16 (4) ◽  
pp. 411-420
Author(s):  
Herianto
Keyword(s):  
Heat Exchanger ◽  
Electric Energy ◽  
Thermodynamic Cycle ◽  
Geothermal Field ◽  
Working Fluid ◽  
Fluid Temperature ◽  
Binary Cycle ◽  
Water Separator ◽  
Geothermal Wells

Nowadays, geothermal is one of the most environmentally friendly energy that can replace the role of fossils energy by converting steam to electricity. Brine is one of the by-products of the production of geothermal wells that are generally not used or simply re-injected. In fact, brine can be converted into electricity using the binary cycle process. In binary cycle, brine from separator is used as a heater of working fluid and transform it into a vapor phase. The vapor will be used to turn turbines and generators to produce electricity. The working fluid selection in accordance with the heating fluid temperature becomes important because it results in optimization of the thermodynamic cycle. The temperature of the wellhead in the geothermal field will decrease 3% per year and reducing the heating fluid temperature in heat exchanger. So, in this paper intends to utilizes brine to heat the heat exchanger by using iso-butane, n-pentane, and iso-pentane because its critical temperature can be stable at 193℃ wellhead temperatures. From the results of predictions from brain 2 production well for 17 years with iso-butane in this binary cycle planning, can utilize waste brine water separator to converse electric energy to produce 4 MWh electricity.

Assessment of Tesla Turbine Performance for Small Scale Rankine Combined Heat and Power Systems

2010 ◽  
Vol 132 (12) ◽  
Author(s):  
Van P. Carey
Keyword(s):  
Power Systems ◽  
Residential Buildings ◽  
Rankine Cycle ◽  
Combined Heat And Power ◽  
Operating Conditions ◽  
Working Fluid ◽  
Small Scale ◽  
Manufacturing Cost ◽  
Turbine Design ◽  
The Impact

For solar Rankine cycle combined heat and power systems for residential buildings and other small-scale applications (producing 1–10 kWe), a low manufacturing cost, robust, and durable expander is especially attractive. The Tesla-type turbine design has these desired features. This paper summarizes a theoretical exploration of the performance of a Tesla turbine as the expander in a small-scale Rankine cycle combined heat and power system. A one-dimensional idealized model of momentum transfer in the turbine rotor is presented, which can be used to predict the efficiency of the turbine for typical conditions in these systems. The model adopts a nondimensional formulation that identifies the dimensionless parameters that dictate performance features of the turbine. The model is shown to agree well with experimental performance data obtained in earlier tests of prototype Tesla turbine units. The model is used to explore the performance of this type of turbine for Rankine cycle applications using water as a working fluid. The model indicates that isentropic efficiencies above 0.75 can be achieved if the operating conditions are tailored in an optimal way. The scalability of the turbine design, and the impact of the theoretical model predictions on the development of solar combined heat and power systems are also discussed.

A Preliminary Turbine Design for an Organic Rankine Cycle

2013 ◽  
Author(s):  
T. Efstathiadis ◽  
M. Rivarolo ◽  
A. I. Kalfas ◽  
A. Traverso ◽  
P. Seferlis
Keyword(s):  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Operating Conditions ◽  
Design Parameters ◽  
Working Fluid ◽  
Energy Sources ◽  
Small Scale ◽  
Choked Flow ◽  
Turbine Speed ◽  
Turbine Design

An increasing trend in exploiting low enthalpy content energy sources, has led to a renewed interest in small-scale turbines for Organic Rankine Cycle applications. The design concept for such turbines can be quite different from either standard gas or steam turbine designs. The limited enthalpic content of many energy sources enforces the use of organic working media, with unusual properties for the turbine. A versatile cycle design and optimization requires the parameterization of the prime turbine design. In order to address the major challenges involved in this process, the present study discusses the preliminary design of an electricity-producing turbine, in the range of 100 kWel, for a low enthalpy organic Rankine cycle. There are many potential applications of this power generating turbine including geothermal and solar thermal fields or waste heat of PEM type fuel cells. An integrated model of equations has been developed, accordingly. The model aims to assess the performance of an organic cycle for various working fluids, including NH3, R600a and R-134a. The most appropriate working fluid has been chosen, taking into consideration its influence on both cycle efficiency and the specific volume ratio. The influence of this choice is of particular importance at turbine extreme operating conditions, which are strongly related to the turbine size. In order to assess the influence of various design parameters, a turbine design tool has been developed and applied to preliminarily define the blading geometry. Finally, a couple of competitive turbine designs have been developed. In one approach, the turbine speed is restricted to subsonic domain, while in the other approach the turbine speed is transonic, resulting to choked flow at the turbine throat. The two approaches have been evaluated in terms of turbine compactness and machine modularity. Results show that keeping the crucial parameters of the geometrical formation of the blade constant, turbine size could become significantly smaller decreasing up to 90% compared its original value.

Numerical Investigation of Aerodynamic Radial and Axial Impeller Forces in a Turbocharger

2011 ◽  
Author(s):  
Henning Raetz ◽  
Jasper Kammeyer ◽  
Christoph K. Natkaniec ◽  
Joerg R. Seume
Keyword(s):  
Numerical Simulations ◽  
Numerical Investigation ◽  
Operating Conditions ◽  
Aerodynamic Forces ◽  
Cfd Simulations ◽  
Axial Forces ◽  
Ansys Cfx ◽  
Radial Turbines ◽  
Bearing Friction

Aerodynamic forces are a major cause of turbocharger bearing friction. Thus, numerical simulations with ANSYS CFX are performed for a turbocharger turbine and compressor in order to determine these forces. Today, in common turbocharger CFD simulations the influence of the impeller backside cavity and blow-by are usually neglected. As a consequence, the axial forces on the impeller cannot be correctly determined. In this study therefore, the impeller backside cavity and blow-by were taken into account. Additionally, the influence of different operating conditions as well as different turbine and compressor blow-by flows were investigated. Finally, the resulting aerodynamic impeller forces of a turbocharger were analysed and visualized. The results show some trends which agree with the impeller forces of larger radial turbines and compressors published in literature. However some turbocharger-specific differences are identified, e.g. the wide operation range of a turbocharger. The influences of blow-by are found to be small but not negligible.

Numerical Study of Straight Annular Seals Versus Convergent Annular Seals at Different Geometries, Surface Roughness, and Operating Conditions

2013 ◽  
Author(s):  
Serafettin Ustun ◽  
Emanuel Marsis ◽  
Gerald Morrison
Keyword(s):  
Surface Roughness ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Numerical Study ◽  
Operating Conditions ◽  
Working Fluid ◽  
Axial Pressure ◽  
Cfd Simulations ◽  
Axial Pressure Gradient ◽  
Annular Seals

Annular seals are used in many turbomachineries to reduce the leakage from high to low pressure zones. In this paper, 2D CFD simulations are used to analyze the flow inside straight annular seals and convergent tapered annular seals with two different exit clearances. The working fluid used was water. The effect of the geometry and surface roughness on the seal performance was studied at different differential pressures and rotor speeds. Moreover, a new design parameter is introduced that relates the normalized axial pressure gradient to the axial wall shear stress for straight and convergent annular seals. This ratio was found to be constant at different seal geometries, exit clearances, differential pressures, and rotor speeds. This allows designers to consider the effects of various convergent tapered seal designs upon the rotordynamic characteristics of the seal without requiring individual CFD simulations.

Optimisation Methods for Coupled Thermodynamic and 1D Design of Radial-Inflow Turbines

2014 ◽  
Author(s):  
Rodney Persky ◽  
Emilie Sauret ◽  
Lin Ma
Keyword(s):  
Thermodynamic Cycle ◽  
Performance Estimation ◽  
Working Fluid ◽  
Preliminary Design ◽  
Design Code ◽  
Organic Rankine Cycles ◽  
The One ◽  
Optimisation Methods ◽  
Turbine Design ◽  
Optimisation Procedure

Optimisation is a fundamental step in the turbine design process, especially in the development of non-classical designs of radial-inflow turbines working with high-density fluids in low-temperature Organic Rankine Cycles (ORCs). The present work discusses the simultaneous optimisation of the thermodynamic cycle and the one-dimensional design of radial-inflow turbines. In particular, the work describes the integration between a 1D meanline preliminary design code adapted to real gases and the performance estimation approach for radial-inflow turbines in an established ORC cycle analysis procedure. The optimisation approach is split in two distinct loops; the inner operates on the 1D design based on the parameters received from the outer loop, which optimises the thermodynamic cycle. The method uses parameters including brine flow rate, temperature and working fluid, shifting assumptions such as head and flow coefficients into the optimisation routine. The discussed design and optimisation method is then validated against published benchmark cases. Finally, using the same conditions, the coupled optimisation procedure is extended to the preliminary design of a radial-inflow turbine with R143a as working fluid in realistic geothermal conditions and compared against results from commercially-available software RITAL from Concepts-NREC.

Investigating the Effect of Changing the Working Fluid on the Three-Dimensional Flow Within Organic Rankine Cycle Turbines

2016 ◽  
Author(s):  
M. White ◽  
A. I. Sayma
Keyword(s):  
Low Cost ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
High Volume ◽  
Detailed Comparison ◽  
Operating Conditions ◽  
Working Fluid ◽  
Working Fluids ◽  
Turbine Design ◽  
Similitude Theory

For small and micro scale (< 50 kWe) organic Rankine cycle (ORC) systems to be commercially viable, systems are required that can operate efficiently over a range of operating conditions. This will lead to the high volume, low cost production that is critical to improve the current economy of scale, and reduce system costs. This requirement will inevitably mean utilising the same system within a range of different applications and may also require the same turbine to operate in different systems where the working fluid may change. Under these circumstances it is therefore important to develop suitable models that can determine the off design performance of these turbines. This will help to understand how the performance of existing ORC turbines responds to such changes. This topic is also of interest when considering retrofitting existing systems with more modern working fluids, which meet current environmental regulations. Recent work by the authors has developed a turbine design model and produced a candidate radial turbine design. Furthermore a modified similitude theory has been developed and validated, which can be used to predict turbine performance following a change in working fluid. This paper extends this analysis to a wider array of working fluids, and in addition to comparing the important performance parameters such as mass flow rate and turbine efficiency, a detailed comparison of the resulting flow field, blade loading distributions and velocity triangles is also presented. Predictions made using the modified similitude theory are compared to steady and unsteady 3D RANS CFD simulations completed using the commercial solver ANSYS CFX. Real fluid properties are accounted for by generating property tables using REFPROP. By comparing these important flow features the validity of the modified similitude model can be examined to a much greater extent.

scholarly journals Experimental Analysis of Refrigeration Ejector System by using Different Organic Refrigerants

2021 ◽  
Vol 9 (VII) ◽  
pp. 281-288
Author(s):  
P. V. Wakchaure
Keyword(s):  
Experimental Analysis ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Optimum Operating ◽  
Working Fluid ◽  
Cfd Simulations ◽  
Evaporator Temperature ◽  
Optimum Operating Condition ◽  
Condenser Temperature ◽  
Ejector System

This paper presents the experimental analysis performed on ejectors to optimize operating conditions like evaporator temperature, condenser temperature and generator temperature. Using the environmentally friendly working fluid R134a, R152a, R600a, R717 (Ammonia). Parametric analysis was performed to review the effect of blending chamber geometry on ejector performance which has direct impact on coefficient of performance of ejector refrigeration cycles. Results show that operating conditions and thus the effect of the deflection of the primary flow on the secondary flow is set. CFD simulations was performed to identify optimum geometry and optimum operating condition

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