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The document is divided in two parts. The first one proposes an ORC model developed at (and for) Enertime SA, a French company that sells medium scale ORC machines and engineering services. This model, developed in Python 3.4, is able to cover a wide range of medium to large scale machines, and to answer to simulation and design problems. It is designed to be as general as possible, but with sufficient accuracy and the opportunity for easy further development. The first part of the report is thus dedicated to the description of the model and its implementation.

In a second part, the model is confronted to two case studies. The first one is a waste heat recovery ORC of 3 MW based in China. Measurements were retrieved from effective operating points to analyze and validate the accuracy of the model. The second one focuses on a specific application of the model in order to illustrate the potential of it. The model is there used to answer to a specific industrial problem related to the design and the control of an air-condenser in a geothermal ORC application.

The model presented in this paper is able to design and simulate medium to large scale Organic Rankine Cycles (ORC) with shell and tubes heat exchangers in different configurations with good robustness. It allows to add a recuperator and/or a preheater in parallel or in series. The Moving Boundary Model that has been implemented allows to simulate almost all temperature profiles. Some simulation equations that have been used were simplified in order to obtain a user-friendly tool that does not require too much upstream research or information to get acceptable results. Of course, this implies a limited accuracy. Still, it is shown that model provides rather good order of magnitude, considering the apparent simplicity of some constituting equations.

ORC, Modelling, Validation --- Waste Heat Recovery --- Ingénierie, informatique & technologie > Energie

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Turboexpanders and Process Applications offers readers complete application criteria, functional parameters, and selection guidelines. This book is intended for the widest possible spectrum of engineering functions, including technical support, maintenance, operating, and managerial personnel in process plants, refineries, air liquefaction, natural gas separation, geothermal mining, and design contracting.The text distinguishes between cryogenic turboexpanders that are used to recover power from extremely cold gases, and hot gas expanders that accomplish the same objective with gases

Heat recovery. --- Turboexpanders. --- Expansion turbines --- Turbines --- Recovery of waste heat --- Waste heat recovery --- Cogeneration of electric power and heat --- Heat engineering --- Heat regenerators --- Waste heat

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Future European regulations imposing large decrease in CO2 emissions force the manufacturers of heavy-duty vehicles to implement innovative solutions to achieve these challenging targets. In this context, waste heat recovery systems represent a suitable solution to exploit thermal energy lost to the ambient by diesel engines. To this end, waste heat recovery by means of an Organic Rankine cycle (ORC) is considered as a promising technology. This thermodynamic bottoming cycle aims to recover thermal power in order to produce electricity on-board, that can be injected into mild-hybrid drivelines.
Volvo Trucks is studying for many years this fuel-saving technology. In the scope of their current project in which this internship takes part, exhaust gases downstream the exhaust after treatment system are exploited as heat source. The heat sink is simply the ambient air, driven towards the condenser placed behind the cab by two fans. A piston expander is used to produce mechanical power, which is in turn converted into electricity to charge a 48V battery of a mild-hybrid truck.
The modelling of an ORC is a major aspect of the system design methodology. Indeed, simulations are used in the early design phase to compare several system architectures and to select the most appropriated working fluid. At a later stage, the plant model can be exploited to design the controller of the ORC system. It is thus essential to develop a precise and efficient model integrating all the components of the Rankine cycle (heat exchangers, expander, pump, etc.) as well as an accurate procedure to compute working fluid properties. In this context, the present work aims to improve the ORC simulation tool developed by Volvo Trucks on Matlab-Simulink.
At first, a new moving boundaries (MB) model of heat exchanger is developed to replace the previous one, based on a finite volumes (FV) approach. This new model is as accurate as the FV model, but it is computationally faster. This robust model takes the form of a Simulink library and is exploited to model the exhaust boiler as well as the air condenser in the complete Rankine system model. It is validated regarding both steady-state and transient simulations. Thanks to this new approach of heat exchanger modelling, the computational time required to perform simulations of the ORC during a road driving cycle is drastically reduced (-72%).
Secondly, this master thesis is dedicated to the modelling of the lubricant added to the working fluid performing the Rankine cycle. This oil is needed in practice to ensure the lubrication of the piston expander, but its presence was neglected up to now in the Rankine simulation tool where pure working fluid properties are assumed. However, a brief literature review shows that it could have a significant impact on ORC performances. To this end, an empirical solubility model is exploited to compute thermodynamic properties of the mixture composed of working fluid (cyclopentane) and Polyalkylene Glycol (PAG) synthetic oil. In addition, all the components of the Rankine model are revised to take into account the presence of lubricant. This study concludes that the net ORC power is clearly impacted by the presence of lubricant. This decrease in net power depends on the exhaust conditions, the ambient air temperature and the oil circulation rate.

waste heat recovery --- organic Rankine cycle --- automotive --- modelling --- heat exchanger --- moving boundaries --- heat transfer --- PID controller --- lubricant --- solubility model --- Ingénierie, informatique & technologie > Ingénierie mécanique

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Heat exchangers --- Heat recovery --- Heat engineering --- Recovery of waste heat --- Waste heat recovery --- Chemical engineering --- Heat --- Refrigeration and refrigerating machinery --- Cogeneration of electric power and heat --- Heat regenerators --- Waste heat --- Mechanical engineering --- Thermodynamics --- Equipment and supplies --- Transmission

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Heat recovery --- Heat exchangers --- Chaleur --- Échangeurs de chaleur --- Récupération --- Recovery of waste heat --- Waste heat recovery --- Chemical engineering --- Heat --- Refrigeration and refrigerating machinery --- Cogeneration of electric power and heat --- Heat engineering --- Heat regenerators --- Waste heat --- Equipment and supplies --- Transmission