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

2009 ◽  
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 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 combine 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 non-dimensional 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 0.70 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 development of solar combined heat and power systems are also discussed.

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.

Radial Inflow Turbine Assessment for Small-Scale Concentrated Solar Rankine Combined Heat and Power Technology

2010 ◽  
Author(s):  
Deborah A. Sunter ◽  
Van P. Carey ◽  
Zack Norwood
Keyword(s):  
Rural Communities ◽  
Power Systems ◽  
Residential Buildings ◽  
Combined Heat And Power ◽  
Operating Conditions ◽  
Geometric Parameters ◽  
Small Scale ◽  
Brayton Cycle ◽  
Analysis Tools ◽  
Radial Inflow Turbine

Recent studies suggest that small scale (5–10kW) distributed solar Rankine combined heat and power could be a viable renewable energy strategy for displacing fossil fuel use in residential buildings, small commercial buildings, or developing rural communities. One of the primary obstacles of scaling down solar Rankine technology to this level is finding an appropriate expander design. This paper considers the radial-inflow turbine for such an application. Although well-tested methodologies exist for design analysis of radial inflow turbines, existing analysis tools are generally focused on machines using a combustion gases in a Brayton cycle. Use of Rankine cycle working fluids under conditions optimal for small scale Rankine solar systems result in turbine operating conditions that can be dramatically different from those in combustion-based Brayton cycle power systems. This investigation explored how analysis tools developed by NASA and others for conventional Brayton cycle power systems can be adapted to analyze and design radial inflow expanders for small scale Rankine solar combined heat and power systems. Using a 1D model derived from analysis methodologies used by NASA for conventional aerospace gas turbine power applications, the effect of reduced power output on performance is explored. Since the model contains several non-dimensional variables, a variety of geometries are surveyed, and performance sensitivity to various geometric parameters is observed. The interplay between radial inflow turbine performance and cycle efficiency for the system is examined in detail. Several fluids are compared to access how critical temperature and the shape of the saturation dome affect thermodynamic performance of the cycle and efficiency of the turbine. Conclusions regarding optimal fluids and geometric parameters for the radial-inflow turbine are discussed.

scholarly journals Sensitivity of Supersonic ORC Turbine Injector Designs to Fluctuating Operating Conditions

2015 ◽  
Author(s):  
Elio A. Bufi ◽  
Paola Cinnella ◽  
Xavier Merle
Keyword(s):  
Method Of Characteristics ◽  
Organic Rankine Cycle ◽  
Design Procedure ◽  
Rankine Cycle ◽  
Operating Conditions ◽  
Real Gas ◽  
Real Gas Effects ◽  
Nozzle Shape ◽  
Turbine Design ◽  
The Impact

The design of an efficient organic rankine cycle (ORC) expander needs to take properly into account strong real gas effects that may occur in given ranges of operating conditions, which can also be highly variable. In this work, we first design ORC turbine geometries by means of a fast 2-D design procedure based on the method of characteristics (MOC) for supersonic nozzles characterized by strong real gas effects. Thanks to a geometric post-processing procedure, the resulting nozzle shape is then adapted to generate an axial ORC blade vane geometry. Subsequently, the impact of uncertain operating conditions on turbine design is investigated by coupling the MOC algorithm with a Probabilistic Collocation Method (PCM) algorithm. Besides, the injector geometry generated at nominal operating conditions is simulated by means of an in-house CFD solver. The code is coupled to the PCM algorithm and a performance sensitivity analysis, in terms of adiabatic efficiency and power output, to variations of the operating conditions is carried out.

Optimum Microturbine Sizing in Small Scale CHP Systems

2011 ◽  
Author(s):  
Mehdi Aghaei Meybodi ◽  
Masud Behnia
Keyword(s):  
Power Systems ◽  
Carbon Tax ◽  
Combined Heat And Power ◽  
Small Scale ◽  
Optimum Number ◽  
Prime Mover ◽  
Present Worth ◽  
Prime Movers ◽  
Chp System ◽  
The Impact

Microturbines are ideally suited for distributed generation applications due to their flexibility in connection methods. They can be stacked in parallel for larger loads and provide stable and reliable power generation. One of the main applications of microturbines is operating as the prime mover in a combined heat and power (CHP) system. CHP systems are considered to be one of the best ways to produce heat and power with efficient fossil fuel consumption. Further, these systems emit less pollution compared to separate productions of the same amount of electricity and heat. In order to optimally benefit from combined heat and power systems, the proper sizing of prime movers is of paramount importance. This paper presents a technical-economic method for selecting the optimum number and nominal power as well as planning the operational strategy of microturbines as the prime movers of small scale combined heat and power systems (capacities up to 500 kW) in three modes of operation: one-way connection (OWC) mode, two-way connection (TWC) mode, and heat demand following (HDF) mode. In the proposed sizing procedure both performance characteristics of the prime mover and economic parameters (i.e. capital and maintenance costs) are taken into account. As the criterion for decision making Net Present Worth (NPW) is used. In our analysis we have also considered the impact of carbon tax on the economics of generation. The proposed approach may also be used for other types of prime movers as well as other sizes of CHP system.

Review of Expander Selection for Small-Scale Organic Rankine Cycle

2014 ◽  
Author(s):  
Saeedeh Saghlatoun ◽  
Weilin Zhuge ◽  
Yangjun Zhang
Keyword(s):  
Internal Combustion Engines ◽  
Large Scale ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Operating Conditions ◽  
Small Scale ◽  
Manufacturing Cost ◽  
Operating Characteristics ◽  
Small Scale Industries

After more than twenty years working on the selection of an appropriate expander for Organic Rankine cycles and wide research and attentions about its influence on the performance and total cost of waste heat recovery systems, now there is a good-enough background studies and achievement for large scale applications. But small-scale industries is like a art space to modify and revise the previous results. As it is clearly known, in small-scale applications and industries especially in internal combustion engines, besides the investigation of performance, physical properties and final efficiency of expander, other parameters should be analyzed accurately like manufacturing cost, availability, reliability, sensitivity to operating condition fluctuations. Due to a significant role of expander equipment to enhance the efficiency of ORC system in the first step expanders is investigated. In this paper, as per related operating characteristics, a complete comparison of small-scale expanders will be debated to guide designers to select more appropriate and the best efficient expansion machine as per their requirements. According to available literatures there is more need to do research about different types of expanders with various operating conditions in small-scale industries.

scholarly journals Dynamic Modeling and Control System Definition for a Micro-CSP Plant Coupled With Thermal Storage Unit

2014 ◽  
Author(s):  
Melissa K. Ireland ◽  
Matthew S. Orosz ◽  
J. G. Brisson ◽  
Adriano Desideri ◽  
Sylvain Quoilin
Keyword(s):  
Rural Communities ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Thermal Storage ◽  
Energy Coupling ◽  
Operating Conditions ◽  
Small Scale ◽  
Storage Unit ◽  
Modeling And Control ◽  
The Impact

Organic Rankine cycle (ORC) systems are gaining ground as a means of effectively providing sustainable energy. Coupling small-scale ORCs powered by scroll expander-generators with solar thermal collectors and storage can provide combined heat and power to underserved rural communities. Simulation of such systems is instrumental in optimizing their control strategy. However, most models developed so far operate at steady-state or focus either on ORC or on storage dynamics. In this work, a model for the dynamics of the solar ORC system is developed to evaluate the impact of variable heat sources and sinks, thermal storage, and the variable loads associated with distributed generation. This model is then used to assess control schemes that adjust operating conditions for daily environmental variation.

scholarly journals Assessment of a District Trigeneration Biomass Powered Double Organic Rankine Cycle as Primed Mover and Supported Cooling

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1030
Author(s):  
Muhammad Tauseef Nasir ◽  
Michael Chukwuemeka Ekwonu ◽  
Yoonseong Park ◽  
Javad Abolfazli Esfahani ◽  
Kyung Chun Kim
Keyword(s):  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Hot Water ◽  
Design Parameters ◽  
Working Fluid ◽  
Small Scale ◽  
Vapor Compression ◽  
Medium Temperature ◽  
Exergetic Analysis ◽  
The Impact

This study presents a combined cooling, heating, and power system powered by biogas, suitable for small scale communities in remote locations. To run such a system, in order to obtain the daily life essentials of electricity, hot water, and cooling, municipal waste can be considered as an option. Furthermore, the organic Rankine cycle part of the organic Rankine cycle powered vapor compression chiller can be used in times of need for additional electric production. The system comprises a medium temperature organic Rankine cycle utilizing M-xylene as its working fluid, and the cooling was covered by an Isobutane vapor compression cycle powered by an R245fa employing organic Rankine cycle. The system analyzed was designated to provide 250 kW of electricity. The energetic and exergetic analysis was performed, considering several system design parameters. The impact of the design parameters in the prime mover has a much greater effect on the whole system. The system proposed can deliver cooling values at the rate between 9.19 and 22 kW and heating values ranging from 879 up to 1255 kW, depending on the design parameter. Furthermore, the second law efficiency of the system was found to be approximately 56% at the baseline conditions and can be increased to 64.5%.

scholarly journals Working Fluid as a Design Variable for a Family of Small Rankine Power Systems

1967 ◽  
Author(s):  
John W. Bjerklie
Keyword(s):  
Power Systems ◽  
Design Variable ◽  
Rankine Cycle ◽  
Operating Conditions ◽  
Peak Temperature ◽  
Working Fluid ◽  
Operating Speed ◽  
Support Structure ◽  
Working Fluids ◽  
The Family

Many different Rankine-cycle working fluids were considered in sizing turbomachinery for power levels from 50 w to 10 kw. It was found that by using three working fluids over the spectrum of applications that good performance could be achieved over the power range when peak temperature varied between 160 and 1000 F, and sink temperature varied between −65 and 635 F. These operating conditions can be met with as few as three turbine sizes when operating speed is allowed to vary to fit the application. Only one shaft, bearing, and basic support structure is needed for the family.

scholarly journals Numerical Study of Multistage Transcritical Organic Rankine Cycle Axial Turbines

2014 ◽  
Vol 136 (8) ◽  
Author(s):  
L. Sciacovelli ◽  
P. Cinnella
Keyword(s):  
Numerical Study ◽  
Pressure Ratio ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Operating Conditions ◽  
Working Fluid ◽  
Dense Gas ◽  
Working Fluids ◽  
Inlet Conditions ◽  
The Impact

Transonic flows through axial, multistage, transcritical organic rankine cycle (ORC) turbines are investigated by using a numerical solver including advanced multiparameter equations of state and a high-order discretization scheme. The working fluids in use are the refrigerants R134a and R245fa, classified as dense gases due to their complex molecules and relatively high molecular weight. Both inviscid and viscous numerical simulations are carried out to quantify the impact of dense gas effects and viscous effects on turbine performance. Both supercritical and subcritical inlet conditions are studied for the considered working fluids. In the former case, flow across the turbine is transcritical, since turbine output pressure is subcritical. Numerical results show that, due to dense gas effects characterizing the flow at supercritical inlet conditions, supercritical ORC turbines enable, for a given pressure ratio, a higher isentropic efficiency than subcritical turbines using the same working fluid. Moreover, for the selected operating conditions, R134a provides a better performance than R245fa.

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