Dynamic Modeling of Organic Rankine Cycle Power Systems

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Francesco Casella ◽  
Tiemo Mathijssen ◽  
Piero Colonna ◽  
Jos van Buijtenen
Keyword(s):  
Power Systems ◽  
Dynamic Modeling ◽  
Power Plants ◽  
Dynamic Models ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Operating Conditions ◽  
Design And Optimization ◽  
Physically Based ◽  
Key Variables

New promising applications of organic Rankine cycle (ORC) technology, e.g., concentrated solar power, automotive heat recovery and off-grid distributed electricity generation, demand for more dynamic operation of ORC systems. Accurate physically-based dynamic modeling plays an important role in the development of such systems, both during the preliminary design as an aid for configuration and equipment selection, and for control design and optimization purposes. A software library of modular reusable dynamic models of ORC components has been developed in the MODELICA language and is documented in the paper. The model of an exemplary ORC system, namely the 150 kWe Tri-O-Gen ORC turbogenerator is validated using few carefully conceived experiments. The simulations are able to reproduce steady-state and dynamic measurements of key variables, both in nominal and in off-design operating conditions. The validation of the library opens doors to control-related studies, and to the development of more challenging dynamic applications of ORC power plants.

Preliminary Design of the ORCHID: A Facility for Studying Non-Ideal Compressible Fluid Dynamics and Testing ORC Expanders

2016 ◽  
Author(s):  
Adam Joseph Head ◽  
Carlo De Servi ◽  
Emiliano Casati ◽  
Matteo Pini ◽  
Piero Colonna
Keyword(s):  
Power Systems ◽  
Power Output ◽  
Fluid Dynamic ◽  
Supersonic Nozzle ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Operating Conditions ◽  
Performance Estimation ◽  
Preliminary Design ◽  
Integrated Device

Organic Rankine Cycle (ORC) power systems are receiving increased recognition for the conversion of thermal energy when the source potential and/or its temperature are comparatively low. Mini-ORC units in the power output range of 3–50 kWe are actively studied for applications involving heat recovery from automotive engines and the exploitation of solar energy. Efficient expanders are the enabling components of such systems, and all the related developments are at the early research stage. Notably, no experimental gasdynamic data are available in the open literature concerning the fluids and flow conditions of interest for mini-ORC expanders. Therefore, all the performance estimation and the fluid dynamic design methodologies adopted in the field rely on non-validated tools. In order to bridge this gap, a new experimental facility capable of continuous operation is being designed and built at Delft University of Technology, the Netherlands. The Organic Rankine Cycle Hybrid Integrated Device (ORCHID) is a research facility resembling a state-of-the-art high-temperature ORC system. It is flexible enough to treat different working fluids and operating conditions with the added benefit of two interchangeable Test Sections (TS’s). The first TS is a supersonic nozzle with optical access whose purpose is to perform gas dynamic experiments on dense organic flows in order to validate numerical codes. The second TS is a test-bench for mini-ORC expanders of any configuration up to a power output of 100 kWe. This paper presents the preliminary design of the ORCHID setup, discussing how the required operational flexibility was attained. The envisaged experiments of the two TS’s are also described.

scholarly journals A Novel Exergy Indicator for Maximizing Energy Utilization in Low-Temperature ORC

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1598 ◽  
Author(s):  
Marcin Jankowski ◽  
Aleksandra Borsukiewicz
Keyword(s):  
Performance Indicators ◽  
Power Plants ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Operating Conditions ◽  
Energy Utilization ◽  
Preliminary Evaluation ◽  
Outlet Temperature ◽  
Simple Formulation ◽  
Effect Factor

In the last decade, particular attention has been paid to the organic Rankine cycle (ORC) power plant, a technology that implements a classical steam Rankine cycle using low-boiling fluid of organic origin. Depending on the specific application and the choice of the designer, the ORC can be optimized using one or several criteria. The selected objectives reflect various system performance aspects, such as: thermodynamic, economic, environmental or other. In this study, a novel criterion called exergy utilization index (XUI) is defined and used to maximize the utilization of an energy source in the ORC system. The maximization of the proposed indicator is equivalent to bring the heat carrier outlet temperature to the ambient temperature as close as possible. In the studied case, the XUI is applied along with the total heat transfer area of the system, and the multi-objective optimization is performed in order to determine the optimal operating conditions of the ORC. Moreover, to reveal a relationship between the XUI and important ORC performance indicators, a parametric study is conducted. Based on the results, it has been found that high values of the XUI (~80%) correspond to optimal values of exergy-based indicators such as: exergy efficiency, waste exergy ratio, environmental effect factor or exergetic sustainability index. Furthermore, the values of the XUI = 60%–80% are associated with beneficial economic characteristics reflected in a low payback period (<11.3 years). When considering the ecological aspect, the maximization of XUI has resulted in minimization of exergy waste to the environment. In general, the simple formulation and straightforward meaning make the XUI a particularly useful indicator for the preliminary evaluation and design of the ORC. Furthermore, the comparative analysis with respect to other well-known performance indicators has shown that it has a potential to be successfully applied as the objective function in the optimization of ORC power plants.

scholarly journals Design Method and Performance Prediction for Radial-Inflow Turbines of High-Temperature Mini-Organic Rankine Cycle Power Systems

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
Carlo M. De Servi ◽  
Matteo Burigana ◽  
Matteo Pini ◽  
Piero Colonna
Keyword(s):  
Power Systems ◽  
Computational Fluid Dynamic ◽  
Dynamic Models ◽  
Waste Heat ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Loss Models ◽  
Radial Inflow Turbine

The realization of commercial mini organic Rankine cycle (ORC) power systems (tens of kW of power output) is currently pursued by means of various research and development activities. The application driving most of the efforts is the waste heat recovery from long-haul truck engines. Obtaining an efficient mini radial inflow turbine, arguably the most suitable type of expander for this application, is particularly challenging, given the small mass flow rate, and the occurrence of nonideal compressible fluid dynamic effects in the stator. Available design methods are currently based on guidelines and loss models developed mainly for turbochargers. The preliminary geometry is subsequently adapted by means of computational fluid-dynamic calculations with codes that are not validated in case of nonideal compressible flows of organic fluids. An experimental 10 kW mini-ORC radial inflow turbine will be realized and tested in the Propulsion and Power Laboratory of the Delft University of Technology, with the aim of providing measurement datasets for the validation of computational fluid dynamics (CFD) tools and the calibration of empirical loss models. The fluid dynamic design and characterization of this machine is reported here. Notably, the turbine is designed using a meanline model in which fluid-dynamic losses are estimated using semi-empirical correlations for conventional radial turbines. The resulting impeller geometry is then optimized using steady-state three-dimensional computational fluid dynamic models and surrogate-based optimization. Finally, a loss breakdown is performed and the results are compared against those obtained by three-dimensional unsteady fluid-dynamic calculations. The outcomes of the study indicate that the optimal layout of mini-ORC turbines significantly differs from that of radial-inflow turbines (RIT) utilized in more traditional applications, confirming the need for experimental campaigns to support the conception of new design practices.

scholarly journals Heat Exchanger Sizing for Organic Rankine Cycle

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3615 ◽  
Author(s):  
James Bull ◽  
James M. Buick ◽  
Jovana Radulovic
Keyword(s):  
Heat Exchanger ◽  
Power Systems ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Operating Conditions ◽  
Working Fluid ◽  
Two Phase ◽  
Operational Conditions ◽  
Shell And Tube

Approximately 45% of power generated by conventional power systems is wasted due to power conversion process limitations. Waste heat recovery can be achieved in an Organic Rankine Cycle (ORC) by converting low temperature waste heat into useful energy, at relatively low-pressure operating conditions. The ORC system considered in this study utilises R-1234yf as the working fluid; the work output and thermal efficiency were evaluated for several operational pressures. Plate and shell and tube heat exchangers were analysed for the three sections: preheater, evaporator and superheater for the hot side; and precooler and condenser for the cold side. Each heat exchanger section was sized using the appropriate correlation equations for single-phase and two-phase fluid models. The overall heat exchanger size was evaluated for optimal operational conditions. It was found that the plate heat exchanger out-performed the shell and tube in regard to the overall heat transfer coefficient and area.

Modular Trough Power Plants

2001 ◽  
Author(s):  
Vahab Hassani ◽  
Henry W. Price
Keyword(s):  
Rural Communities ◽  
Power Systems ◽  
Power Plants ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Market Potential ◽  
Small Scale ◽  
Number Of Factors ◽  
Electrical Generation ◽  
The Cost

Abstract A number of factors are creating an increased market potential for small trough power technology. These include the need for distributed power systems for rural communities worldwide, the need to generate more electricity by non-combustion renewable processes, the need for sustainable power for economic growth in developing countries, and the deregulation and privatization of the electrical generation sector worldwide. Parabolic trough collector technology has been used in large central station power plants. Organic Rankine cycle (ORC) air-cooled modular power units have been successfully applied for large and small-scale geothermal power plants, with over 600 MW of capacity, during the same period. The merging of these two technologies to produce distributed modular power plants in the 200 kW to 10 MW range offers a new application for both technologies. It is our objective in this paper to introduce a modular trough power plant (MTPP) and discuss its performance and the cost of electricity generation from such system.

scholarly journals An Organic Rankine Cycle Bottoming a Diesel Engine Powered Passenger Car

Energies ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 314 ◽  
Author(s):  
Antonio Mariani ◽  
Maria Laura Mastellone ◽  
Biagio Morrone ◽  
Maria Vittoria Prati ◽  
Andrea Unich
Keyword(s):  
Diesel Engine ◽  
Power Plants ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Operating Conditions ◽  
Working Fluid ◽  
Road Transportation ◽  
Passenger Car ◽  
Engine Efficiency ◽  
Driving Conditions

Organic Rankine Cycle (ORC) power plants are characterized by high efficiency and flexibility, as a result of a high degree of maturity. These systems are particularly suited for recovering energy from low temperature heat sources, such as exhaust heat from other plants. Despite ORCs having been assumed to be appropriate for stationary power plants, since their layout, size and weight constraints are less stringent, they represent a possible solution for improving the efficiency of propulsion systems for road transportation. The present paper investigates an ORC system recovering heat from the exhaust gases of an internal combustion engine. A passenger car with a Diesel engine was tested over a Real Driving Emission (RDE) cycle. During the test exhaust gas mass flow rate and temperature have been measured, thus calculating the enthalpy stream content available as heat addition to ORC plant in actual driving conditions. Engine operating conditions during the test were discretized with a 10-point grid in the engine torque–speed plane. The ten discretized conditions were employed to evaluate the ORC power and the consequent engine efficiency increase in real driving conditions for the actual Rankine cycle. N-pentane (R601) was identified as the working fluid for ORC and R134a was employed as reference fluid for comparison purposes. The achievable power from the ORC system was calculated to be between 0.2 and 1.3 kW, with 13% system efficiency. The engine efficiency increment ranged from 2.0% to 7.5%, with an average efficiency increment of 4.6% over the RDE test.

scholarly journals Component-Oriented Modeling of a Micro-Scale Organic Rankine Cycle System for Waste Heat Recovery Applications

2021 ◽  
Vol 11 (5) ◽  
pp. 1984
Author(s):  
Ramin Moradi ◽  
Emanuele Habib ◽  
Enrico Bocci ◽  
Luca Cioccolanti
Keyword(s):  
Electric Power ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Operating Conditions ◽  
Working Fluid ◽  
Pump Efficiency ◽  
Micro Scale

Organic Rankine cycle (ORC) systems are some of the most suitable technologies to produce electricity from low-temperature waste heat. In this study, a non-regenerative, micro-scale ORC system was tested in off-design conditions using R134a as the working fluid. The experimental data were then used to tune the semi-empirical models of the main components of the system. Eventually, the models were used in a component-oriented system solver to map the system electric performance at varying operating conditions. The analysis highlighted the non-negligible impact of the plunger pump on the system performance Indeed, the experimental results showed that the low pump efficiency in the investigated operating range can lead to negative net electric power in some working conditions. For most data points, the expander and the pump isentropic efficiencies are found in the approximate ranges of 35% to 55% and 17% to 34%, respectively. Furthermore, the maximum net electric power was about 200 W with a net electric efficiency of about 1.2%, thus also stressing the importance of a proper selection of the pump for waste heat recovery applications.

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