References of "Lemort, Vincent"
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See detailExhaust Heat Recovery Rankine System for passenger cars: modelling and design
Glavatskaya, Yulia; Lemort, Vincent ULg; Podevin, Pierre et al

(2011, July)

Nowadays, in average, one third of the fuel energy consumed by an engine is wasted throughout the exhaust gases. The recovery of this amount of energy would enable a reduction of the fuel consumption. One ... [more ▼]

Nowadays, in average, one third of the fuel energy consumed by an engine is wasted throughout the exhaust gases. The recovery of this amount of energy would enable a reduction of the fuel consumption. One solution is to integrate an exhaust heat recovery system based on a Rankine cycle. The first and most crucial step in the design is the definition of its architecture, the definition of the rated operating conditions and the sizing of the different components whilst considering the heat recovery over customer driving cycles. This paper presents a steady-state model of a steam Rankine cycle built by interconnecting sub-models of the heat exchangers, the pump and the expander. All the models were developed under EES (Engineering Equation Solver) environment. The models of heat exchanger are developed using the ε-NTU method. A heat exchanger is subdivided into three zones, each of them being characterized by both the exhaust gases and water side pressure drop as well as heat transfer coefficient. The evaluation of the two-phase zone pressure drop and heat transfer with respect to the vapour quality was carried out. The model of rotary piston expander describes the evolution of the fluid through the device and was split into three global steps: pressure drop across the supply port, isentropic and expansion at constant volume, internal and external heat transfers. The overall simulation model is finally used to predict the performance of the heat recovery system as the operating conditions and geometrical characteristics of each component are modified. An optimal sizing of the system is proposed and the underlying methodology is discussed. The analysis of the results pointed out that the levels of high/low pressure and the amount of superheat are the main parameters that impact the performance of the cycle and the sizing of the components. [less ▲]

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See detailTransient Organic Rankine Cycle Modelling for Waste Heat Recovery on a Truck
Espinosa, Nicolas; Gil-Roman, Ignacio; Didiot, Damien et al

(2011, July)

The Organic Rankine Cycle is showing promising results for waste heat recovery on long haul truck applications. This technology could further increase the efficiency of current truck powertrains. In such ... [more ▼]

The Organic Rankine Cycle is showing promising results for waste heat recovery on long haul truck applications. This technology could further increase the efficiency of current truck powertrains. In such a context, the dynamic simulation of a Rankine cycle is found to be very important to study its starting and shutting down phases, control strategies and their limits. Such studies are not always easy to perform on a test bench. This paper deals with the dynamic simulation of a Rankine cycle done under a one dimension commercial fluid dynamic simulation tool (GT-Power). After a brief summary of the component modelling, the paper focuses on the starting and initialization of the model as well as the strategies applied to make the simulation converge. Tank sizing and temperature limitations are addressed to illustrate the use of the model. [less ▲]

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See detailInvestigation on an air-to-air heat recovery exchanger: modeling and experimental validation in dry conditions
Gendebien, Samuel ULg; Bertagnolio, Stéphane ULg; Georges, Bernard ULg et al

in Proceedings of the RoomVent 2011 Conference (2011, June 21)

This paper deals with the development and the experimental validation of an air-to-air recovery heat exchanger model dedicated to ventilation of residential buildings. The first part of the paper presents ... [more ▼]

This paper deals with the development and the experimental validation of an air-to-air recovery heat exchanger model dedicated to ventilation of residential buildings. The first part of the paper presents a semi-empirical model based on physical characteristics of the heat exchanger. The aim of this model is to predict the behavior of the device in dry conditions. The second part of the paper describes the experimental facility designed to determine the hydraulic and thermal performance of the device and offers a comparison between simulation and experimental results. Finally, the model is calibrated in order to predict the thermal and hydraulic performance of the heat exchanger within respectively, less than 5% and less than 2% of accuracy. [less ▲]

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See detailExperimental characterization of a hermetic scroll expander for use in a micro-scale Rankine cycle
Lemort, Vincent ULg; Declaye, Sébastien ULg; Quoilin, Sylvain ULg

in Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy (2011)

This paper presents the results of an experimental study carried out on a prototype of a hermetic scroll expander, integrated into a gas cycle test rig, whose working fluid is HFC-245fa. This system was ... [more ▼]

This paper presents the results of an experimental study carried out on a prototype of a hermetic scroll expander, integrated into a gas cycle test rig, whose working fluid is HFC-245fa. This system was designed to test only the performance of the expander. It is mainly made up of a scroll compressor, a scroll expander, a heat exchanger and a by-pass valve. The latter is used to adjust the pressure ratio imposed to the expander. The expander is originally a compressor designed for heat pump applications and characterized by a nominal power input of 2.5 kWe. Performance of the expander is evaluated in terms of isentropic effectiveness and filling factor as function of the main operating conditions. The study also investigates the impact of oil mass fraction on the expander performance. Maximum overall isentropic effectiveness of 71.03% is measured, which is partly explained by the good volumetric performance of the machine. Using the experimental data, parameters of a semi-empirical simulation model of the expander are identified. This model is used to analyze the measured performance of the expander. Finally, a polynomial empirical model of the expander is proposed for fast and robust simulations of ORC systems. [less ▲]

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See detailPerformance and Design optimization of a low-cost solar organic Rankine cycle for remote power generation
Quoilin, Sylvain ULg; Orosz, Matthew; Lemort, Vincent ULg

in Solar Energy (2011)

Recent interest in small-scale solar thermal combined heat and power (CHP) power systems has coincided with demand growth for distributed electricity supplies in areas poorly served by centralized power ... [more ▼]

Recent interest in small-scale solar thermal combined heat and power (CHP) power systems has coincided with demand growth for distributed electricity supplies in areas poorly served by centralized power stations. One potential technical approach to meeting this demand is the parabolic trough solar thermal collector coupled with an organic Rankine cycle (ORC) heat engine. The paper describes the design of a solar organic Rankine cycle being installed in Lesotho for rural electrification purpose. The system consists of parabolic though collectors, a storages tank, and a small-scale ORC engine using scroll expanders. A model of each component is developed taking into account the main physical and mechanical phenomena occurring in the cycle and based on experimental data for the main key components. The model allows sizing the different components of the cycle and evaluates the performance of the system. Different working fluids are compared, and two different expansion machine configurations are simulated (single and double stage). [less ▲]

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See detailThe Organic Rankine Cycle: Thermodynamics, Applications and Optimization
Quoilin, Sylvain ULg; Lemort, Vincent ULg

in Exergy, Energy system analysis, and Optimization (2011)

New energy conversion technologies are required in order to ensure the production of electricity without generating environmental pollution. Among them, low-grade heat sources or low power heat sources ... [more ▼]

New energy conversion technologies are required in order to ensure the production of electricity without generating environmental pollution. Among them, low-grade heat sources or low power heat sources present an important potential of development. The Organic Rankine Cycle (ORC) is a well known technology since the early 80’s. A large amount of ORC power plants have been built, mainly for geothermal, waste heat recovery and combined heat and power applications. This technology shows a number of advantages over the traditional steam Rankine cycle that make it more profitable for power plants with a limited electrical output power (typically lower than 1 MWe), despite a lower efficiency. The optimization of the ORC is quite different from that of the steam cycle, mainly because of the heat source temperature limitation, and because there is usually no constraint regarding the vapour quality at the end of the expansion. This chapter presents an overview of the current state of the art in the ORC technology and exposes the main target applications. The modelling of such a cycle is described and issues such as fluid selection, optimization or control of the cycle are thoroughly reviewed. [less ▲]

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See detailThermo-Economic optimization of waste heat recovery Organic Rankine Cycles
Quoilin, Sylvain ULg; Declaye, Sébastien ULg; Tchanche, Bertrand F. et al

in Applied Thermal Engineering (2011)

The present paper focuses both on the thermodynamic and on the economic optimization of a small scale ORC in waste heat recovery application. A sizing model of the ORC is proposed, capable of predicting ... [more ▼]

The present paper focuses both on the thermodynamic and on the economic optimization of a small scale ORC in waste heat recovery application. A sizing model of the ORC is proposed, capable of predicting the cycle performance with different working fluids and different components sizes. The working fluids considered are R245fa, R123, n-butane, n-pentane and R1234yf and Solkatherm. Results indicate that, for the same fluid, the objective functions (economics profitability, thermodynamic efficiency) lead to different optimal working conditions in terms of evaporating temperature: the operating point for maximum power doesn’t correspond to that of the minimum specific investment cost: The economical optimum is obtained for n-butane with a specific cost of 2136 €/kW, a net output power of 4.2 kW, and an overall efficiency of 4.47%, while the thermodynamic optimum is obtained for the same fluid with an overall efficiency of 5.22%. It is also noted that the two optimizations can even lead to the selection of a different working fluid. This is mainly due to additional fluid properties that are not taken into account in the thermodynamic optimization, such as the fluid density: a lower density leads to the selection of bigger components which increases the cost and decreases the economical profitability. [less ▲]

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See detailDynamic modeling and optimal control strategy of waste heat recovery Organic Rankine Cycles
Quoilin, Sylvain ULg; Aumann, Richard; Grill, Andreas et al

in Applied Energy (2011)

Organic Rankine Cycles (ORCs) are particularly suitable for recovering energy from low-grade heat sources. This paper describes the behavior of a small scale ORC used to recover energy from a variable ... [more ▼]

Organic Rankine Cycles (ORCs) are particularly suitable for recovering energy from low-grade heat sources. This paper describes the behavior of a small scale ORC used to recover energy from a variable flow rate and temperature waste heat source. A traditional static model is unable to predict transient behavior in a cycle with a varying thermal source, whereas this capability is essential for simulating an appropriate cycle control strategy during part-load operation and start and stop procedures. A dynamic model of the ORC is therefore proposed focusing specifically on the time-varying performance of the heat exchangers, the dynamics of the other components being of minor importance. Three different control strategies are proposed and compared. The simulation results show that a model predictive control strategy based on the steady-state optimization of the cycle under various conditions is the one showing the best results. [less ▲]

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See detailA Generalized Simulation Model of Chillers and Heat Pumps to be Calibrated on Published Manufacturer's Data
Lemort, Vincent ULg; Bertagnolio, Stéphane ULg

(2010, August 07)

This paper shows how semi-empirical models of chillers and heat pumps can be calibrated on the basis of manufacturer’s published data, which is most of the time the only available source of information. A ... [more ▼]

This paper shows how semi-empirical models of chillers and heat pumps can be calibrated on the basis of manufacturer’s published data, which is most of the time the only available source of information. A calibration methodology is proposed and illustrated for different technologies of vapor-compression machines, pointing out tips and tricks. Whatever the size and technology (e.g. scroll, screw or reciprocating compressors), the semi-empirical model is found to predict both full load and part load performance with a very good accuracy. This is partially due to the tailor-made formalism of the model, which allows describing the main features of the machine. [less ▲]

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See detailEconomic feasibility study of a small scale Organic Rankine Cycle system in waste heat recovery applications
Tchanche, Bertrand; Quoilin, Sylvain ULg; Declaye, Sébastien ULg et al

(2010, August)

The Organic Rankine Cycle (ORC) appears progressively as a promising solution to recover waste heat energy from thermal processes for electricity generation. A prototype of small-scale ORC has been built ... [more ▼]

The Organic Rankine Cycle (ORC) appears progressively as a promising solution to recover waste heat energy from thermal processes for electricity generation. A prototype of small-scale ORC has been built and successfully tested at the University of Liège. It uses R-245fa and R-123 as working fluid, and an oil-free scroll compressor adapted to run in expander mode. Thermodynamic model of the system was derived and validated for performance prediction. The validated thermodynamic model is used to optimize the operation of the small ORC in waste heat recovery application (ORC-WHR). For exhaust gases at 180 ºC and a mass flow rate of 0.21 kg/s, a maximum net power output of 2 kWe is obtained for an evaporator pressure of 11.84 bar. The cycle thermal efficiency is 8.23 and the recuperation efficiency, 66.32%. Based on the aforementioned conditions, the economic assessment of small scale ORC-WHR was carried out using economic criteria such as levelized electricity cost (LEC), Net present value (NPV) and depreciated payback period (DPP). For a 2kWe ORC-WHR, the specific installed cost is 5775 €/kW with a LEC of 13.27 c€/kWh while for a 50 kWe, the specific installed cost is about 3034 €/kW and the LEC, 7c€/kWh. For an electricity unit price of 20 c€/kWh, the payback period of a 2 kWe system is 6 years while it is 2.5 years for a 50 kWe system. It is concluded from the study that recovering the waste heat by way of ORCs is technically and economically feasible. As recycled energy, waste heat has the same advantages as renewable energy and should benefit from the same legislative conditions (Feed-in-Laws). [less ▲]

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See detailDesign and Experimental investigation of a Small scale organic Rankine using a scroll expander
Declaye, Sébastien ULg; Quoilin, Sylvain ULg; Lemort, Vincent ULg

in Proceeding of the 13th International Refrigeration and Air Conditioning Conference at Purdue (2010, July 11)

The world is facing a historical increase in energy demand and energy consumption. As consequence the conventional fossil fuels are depleting faster with an inherent pollution causing sever damages to our ... [more ▼]

The world is facing a historical increase in energy demand and energy consumption. As consequence the conventional fossil fuels are depleting faster with an inherent pollution causing sever damages to our environment. Renewable energy sources are considered as a solution to both environmental issue and energy demand. At the same time a lot of waste heat is witnessed in processes in industries and other thermal devices such internal combustion engines. Our objective is to propose a solution to recover this heat wasted. The organic Rankine cycle appeared to us as a solution. This paper presents a study carried out on a prototype of small scale organic Rankine cycle (ORC) driven by two waste heat hot air streams. The prototype was designed using a diaphragm pump, a set of plate heat exchangers and an oil-free scroll compressor adapted to run in expander mode. The available literature on Organic Rankine Cycles only proposes theoretical studies of fluid selection for a given application. This study aims at comparing fluids experimentally. Therefore, several fluids (including R245fa and R123) were tested in the prototype and the performance was measured. The tests were performed to study the performance of the ORC system and the expander over a wide range of working conditions. The temperature of the heat sources varied between 150°C and 200°C. The maximum expander shaft power was above 2kW and maximum expander efficiency was 70%. These tests allowed to point out the critical characteristics that should be taken into account while selecting the components for the design of an ORC. [less ▲]

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See detailExpansion Machine and fluid selection for the Organic Rankine Cycle
Quoilin, Sylvain ULg; Declaye, Sébastien ULg; Lemort, Vincent ULg

in Proceedings of the 7th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics (2010, July)

This paper considers a whole range of ORC applications, in terms of power (from the kW-scale to the multi-MW plants), heat source temperature (from 90°C to more than 300°C) or heat source nature (solar ... [more ▼]

This paper considers a whole range of ORC applications, in terms of power (from the kW-scale to the multi-MW plants), heat source temperature (from 90°C to more than 300°C) or heat source nature (solar, biomass, waste heat recovery, geothermy, etc.). Five typical ORC applications are considered in terms of evaporating and condensing temperature. A screening of the most used ORC working fluids is performed, and their thermodynamics performances are compared with respect to the foreseen application. A detailed analysis of the most common expansion machines is then conducted, by comparing their respective operating maps for each fluid and for each application type. The considered expansion machines are the single-stage radial-inflow turbine, the screw expander, and the scroll expander, which are widely used in commercial applications and/or in scientific literature. The limitations of these machines are listed and considered to define an operating map for each considered fluid. Finally, the allowable power range is described with respect to the application and to the selected expansion device. [less ▲]

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See detailExperimental Analysis of Radiant Ceiling Systems Coupled to its Environment
Fonseca, Néstor; Cuevas, Cristian; Lemort, Vincent ULg

(2010, July)

This paper presents the results of an experimental analysis of the radiant ceiling systems in both heating and cooling modes coupled to its environment (fenestration, walls, internal loads and ventilation ... [more ▼]

This paper presents the results of an experimental analysis of the radiant ceiling systems in both heating and cooling modes coupled to its environment (fenestration, walls, internal loads and ventilation system). The main objective of this study is to present the results of the systems performance and measurement methods used to evaluate the influence of some important parameters on the radiant ceiling capacity and comfort conditions. Two test chambers are adapted in a way to reproduce as good as possible the characteristics of the real offices located in Brussels. Forty-six tests were performed in which the main objective was to observe the influence of parameters such as the mass flow rate, supply water temperature and thermal load distribution, fenestration and ventilation system effects. Laboratory test results show that the influence of surfaces temperatures inside the room, especially the facade, is considerable. Therefore, the system must be evaluated together with its designed environment and not as separate HVAC equipment. [less ▲]

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See detailDynamic Modeling and Validation of Radiant Ceiling Systems Coupled to its Environment
Fonseca, Néstor; Cuevas, Cristian; Lemort, Vincent ULg

(2010, July)

This paper presents the results of a study performed in order to develop a dynamic model of radiant ceiling panels in heating or cooling modes coupled to its environment (fenestration, walls, internal ... [more ▼]

This paper presents the results of a study performed in order to develop a dynamic model of radiant ceiling panels in heating or cooling modes coupled to its environment (fenestration, walls, internal loads and ventilation system). The model considers the radiant panels as a dynamic-state finned heat exchanger connected to a detailed lumped dynamic model of the building (R-C network). The behavior of the radiant ceiling system and the interactions with its environment has been experimentally and numerically evaluated. Using as inputs the radiant ceiling and room dimensions, material properties and the transient measurements of air temperature at the adjacent zones, supply air and water temperatures and mass flow rates, the model allows for the estimation of the water exhaust temperature, radiant ceiling average surface temperature, resultant and dry air room temperatures, radiant ceiling power and internal surface temperatures of the room in order to compare with measurements taken during the commissioning process. Two dynamic tests in heating and cooling modes are used to validate the model. [less ▲]

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See detailThe use of semi-empirical modeling to extrapolate chiller performance maps
Lemort, Vincent ULg; Bertagnolio, Stéphane ULg

Conference (2010, June 28)

HVAC&R components operate most of the time in part load conditions for which little data are available from manufacturers. This makes performance prediction difficult. Approaches and problems are ... [more ▼]

HVAC&R components operate most of the time in part load conditions for which little data are available from manufacturers. This makes performance prediction difficult. Approaches and problems are presented for simulating the performance of HVAC&R components under part load conditions and under consideration of dynamic effects such as cycling. The seminar motivates a discussion about HVAC&R component modeling for part load and dynamic conditions and it dscusses what additional data are required from manufacturers to assess the performance at these conditions. [less ▲]

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See detailSimulation of a building and its HVAC system with an equation solver: Application to audit
Bertagnolio, Stéphane ULg; Andre, Philippe ULg; Lemort, Vincent ULg

in Building Simulationa: An international Journal (2010), 3(2), 139-152

A series of building energy simulation tools are being developed to help the building energy auditor in establishing his diagnosis (including benchmarking and detailed analysis of actual energy ... [more ▼]

A series of building energy simulation tools are being developed to help the building energy auditor in establishing his diagnosis (including benchmarking and detailed analysis of actual energy consumption) and in evaluating the selected Energy Conservation Measures (ECMs). A first simulation tool, dedicated to benchmarking, has been presented in a previous paper. The present paper focuses on the second simulation tool, dedicated to inspection and evaluation of ECMs. This Building-HVAC System global model includes simplified models of building zones and of HVAC equipment. Only a limited number of easily identifiable parameters are required. The simplicity of the models and the use of an equation solver to run the simulation ensure good robustness and full transparency. The development, the implementation and the application of these models are discussed. Focus is also given to the calibration of the tools to monthly utility bills. [less ▲]

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See detailEconomic Optimization of Small Scale Organic Rankine Cycles
Tchanche, Bertrand; Quoilin, Sylvain ULg; Declaye, Sébastien ULg et al

(2010, June)

The present paper focuses on the economic optimization of a small scale ORC in waste heat recovery application with specific investment cost as objective function. First, a pre-design model of the ORC was ... [more ▼]

The present paper focuses on the economic optimization of a small scale ORC in waste heat recovery application with specific investment cost as objective function. First, a pre-design model of the ORC was built and simulations run with different working fluids to evaluate their technical performance. In a second step, components and system cost models were built and simulations carried out to evaluate the cost effectiveness of systems associated with different fluids. The working fluids considered are R245fa, R123, R113, n-Pentane and n-Butane. Results indicate that for the same fluid, the point of high performance and that f cost-effectiveness do not match. The operating point for maximum power doesn’t correspond to that of the minimum specific investment cost. For n-Pentane, the maximum net power of 1.98 kW is obtained for an evaporator pressure of 5.14 bar and the specific investment cost is 5450 €/kW. For this same fluid, a minimum specific investment cost of 4440 €/kW is obtained for an evaporator pressure of 8.5 bar and the corresponding power output is 1.745 kW. The mismatch aforementioned is due to the thermodynamic properties such as liquid/vapour densities, which significantly influence system performance and components sizes. Seeking for profitable environmental solutions, economic optimization as a necessary step in the optimization of any thermodynamic system is highly advised. [less ▲]

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See detailComparative validation of three water cooling coil models
Gendebien, Samuel ULg; Bertagnolio, Stéphane ULg; Lemort, Vincent ULg

in Proceedings of the 10th REHVA World Congress - Clima 2010 (2010, May)

Water cooling coils are widely used in common HVAC systems. Accurate and robust cooling coil simulation models are required to perform reliable calculations of building cooling needs. Many different ... [more ▼]

Water cooling coils are widely used in common HVAC systems. Accurate and robust cooling coil simulation models are required to perform reliable calculations of building cooling needs. Many different cooling coil simulation models were developed during the last decades. The most commonly used cooling coil models are presented and compared in terms of implementation in the first part of the paper. A simplified variable boundary model is presented and comparatively and empirically validated to two reference models. [less ▲]

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See detailEvaluation du potentiel de récupération d’énergie à l’échappement d’un moteur TDI à l’aide d’un cycle de Rankine organique (ORC)
Declaye, Sébastien ULg; Quoilin, Sylvain ULg; Lemort, Vincent ULg

Poster (2010, May)

Une étude expérimentale a été menée sur un cycle de Rankine organique de faible puissance (2,5kW). Les résultats expérimentaux ont permis de calibrer un modèle du cycle qui a ensuite été utilisé afin ... [more ▼]

Une étude expérimentale a été menée sur un cycle de Rankine organique de faible puissance (2,5kW). Les résultats expérimentaux ont permis de calibrer un modèle du cycle qui a ensuite été utilisé afin d’évaluer le potentiel de récupération d’énergie à l’échappement d’un moteur TDI pour 13 points de fonctionnement représentatifs. Les résultats montrent la possibilité de produire jusqu’à 2,4kW de puissance mécanique additionnelle. La fraction d’énergie récupérée (ERR) pouvant atteindre 6,8% de la puissance à l’arbre moteur. [less ▲]

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See detailRankine cycle for waste heat recovery on commercial trucks: approach, constraints and modelling
Espinosa, Nicolas; Tilman, Loic; Lemort, Vincent ULg et al

(2010, May)

With increasing oil price and growing interest in cutting green house gases emissions, waste heat recovery techniques appear as a very promising path to enhance engine thermal efficiency ... [more ▼]

With increasing oil price and growing interest in cutting green house gases emissions, waste heat recovery techniques appear as a very promising path to enhance engine thermal efficiency. Thermoelectricity and Rankine cycles are two possible ways to recover thermal energy. The Rankine cycle shows the highest potential due to its higher cycle efficiency in comparison with the current state-of-the-art thermoelectric materials intrinsic conversion ratio. This paper will focus on the Rankine cycle system. The first part of the paper lists and describes the constraints of a heat recovery Rankine cycle system associated to a long haulage truck: limitation of heat available in the heat source, vehicle heat rejection constraints, safety and environmental issues for the working fluid, and backpressures occurring during the heat recovery process. The second part of the paper presents a 0-D simulation model of a Rankine cycle system. It is shown how the model can be used to compare the performance achieved with several working fluids. Moreover, basic thermodynamic limitations of the system are underlined. Conclusions are drawn concerning the limitation of using only thermodynamic simulations. The performance of the condenser (and its influence on the overall performance) has been investigated more in details, which is shown in the third part of the paper. This was carried out based on a 1-D simulation model of the condenser. Influence of the condenser size and ram air effect are discussed, and the impact on the Rankine cycle is assessed. [less ▲]

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