References of "Lebrun, Jean"
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See detailGlobal optimization of the production and the distribution system for typical European HVAC systems
Randaxhe, François ULg; Lemort, Vincent ULg; Lebrun, Jean ULg

in Energy Procedia (2015), 78

European countries have agreed on a new 2030 Framework with a 30% improvement in energy efficiency compared to projection and a 40% cut in greenhouse gas emissions compared to 1990 levels. With an ... [more ▼]

European countries have agreed on a new 2030 Framework with a 30% improvement in energy efficiency compared to projection and a 40% cut in greenhouse gas emissions compared to 1990 levels. With an estimated 11% of all the electrical energy used in Europe consumed by HVAC systems, the improvement of their efficiency is a key element to reach these targets. When looking at the energy flow in typical European HVAC systems, one can observe important degradation in efficiency associated to heating and cooling energy transportation systems together with a non-optimal use of the production plant. These inefficiencies are direct consequences of the system design with, quite often, a lack of consideration of the system part load or its off-design operation. This research attempts to identify the sensitivity of both cooling and heating HVAC systems to these conditions and to propose an approach to optimize the design and the operation of HVAC systems integrated in buildings considering trade-off between primary systems efficiency, distribution losses and auxiliaries consumption. [less ▲]

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See detailLessons Learned from Heat Balance Analysis for Holzkirchen Twin Houses Experiment
Masy, Gabrielle; Rehab, Imane ULg; Andre, Philippe ULg et al

in Energy Procedia (2015)

Holzkirchen full scale dynamic experiments were conducted in the framework of IEA Annex 58 research program with the aim to obtain and apply a high quality experimental dataset for model validation of ... [more ▼]

Holzkirchen full scale dynamic experiments were conducted in the framework of IEA Annex 58 research program with the aim to obtain and apply a high quality experimental dataset for model validation of full scale buildings. A first experiment was conducted in August 2013. Two identical houses were submitted to a side by side experiment, one with blinds up, one with blinds down. That first experience lasted 42 days including an initialization period, a Randomly Ordered Logarithmic Binary Sequence of heat inputs (ROLBS), and a re-initialization followed by a free-float period. A second experiment was conducted in April 2014 in one of the two houses, with higher levels of heating power in the South oriented zones and imposed indoor temperatures in the North oriented zones. Simulations were performed with EES Engineering Equation Solver using simplified RC dynamic models. The discrepancies observed between simulated results and measured data were first explained through a deeper analysis of thermal bridges, a better assessment of solar heat gains and a better assessment of the air duct heat losses. In the second experiment, the results revealed an underestimation of the building transmission heat losses. A candidate explanation might be the air stratification which would enhance heat losses on the ceiling side. A modelization of the upper and lower room air layers was introduced. The resulting simulated indoor temperature profiles were in accordance with the measurements. A complete breakdown of heat losses and heat gains was computed for both houses, using measured temperatures as input data for the simulation. [less ▲]

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See detailComparison of translocation methods to conserve metallophyte communities in the Southeastern D.R. Congo
Le Stradic, Soizig ULg; Seleck, Maxime ULg; Lebrun, Jean ULg et al

in Environmental Science and Pollution Research (2015)

In southeastern Democratic Republic of Congo, unique metallophyte communities supporting numerous endemic species occurred on the highly mineralized copper cobalt (Cu–Co) hills throughout the province ... [more ▼]

In southeastern Democratic Republic of Congo, unique metallophyte communities supporting numerous endemic species occurred on the highly mineralized copper cobalt (Cu–Co) hills throughout the province. These hills are economically valuable mineral reserves; mining activities represent therefore a threat to the long-term persistence of these communities. Ex situ conservation program was set up by a mining company to rescue and conserve the diversity of Cu–Co communities until restoration activities are initiated. Two kinds of Cu–Co communities: the steppe and the steppic savanna, were translocated using topsoil spreading and whole-turf translocation. In this study, we assessed the effectiveness of these two techniques in conserving Cu–Co communities and their potential use in future restoration programs. More than 2 years after the translocation, whole-turf translocation appeared to be the better technique for ex situ conservation of endemic Cu–Co species. Not only did whole-turf successfully translocate numerous target species that were not present in the topsoil areas, but it also resulted in fewer ruderal and non-target species compared to topsoil spreading. Topsoil spreading recorded low seedling emergence from seed bank due to large proportions of dormant seeds or the absence of a seed bank, especially for the steppic savanna. Restoration of the steppe is currently more successful than for steppic savanna where the lack of dominant and structuring species likely contributed to divergence in species composition compared to reference ecosystem. Our study stresses the fact that tropical old-growth grasslands, which require probably several centuries to assemble, are difficult to restore or translocate. © 2015 Springer-Verlag Berlin Heidelberg [less ▲]

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See detailIEA Annex 48: Reversible Air-Conditioning
Andre, Philippe ULg; Lebrun, Jean ULg

Report (2011)

Rapport de synthèse du projet IEA Annex 48: Reversible Air-conditioning

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See detailExperimental study and modeling of an Organic Rankine Cycle using scroll expander
Quoilin, Sylvain ULg; Lemort, Vincent ULg; Lebrun, Jean ULg

in Applied Energy (2010), 87(4), 1260-1268

This paper presents both a numerical model of an Organic Rankine Cycle (ORC) and an experimental study carried out on a prototype working with refrigerant HCFC-123, and whose heat sources consist in two ... [more ▼]

This paper presents both a numerical model of an Organic Rankine Cycle (ORC) and an experimental study carried out on a prototype working with refrigerant HCFC-123, and whose heat sources consist in two hot air flows. The ORC model is built by interconnecting different sub-models: the heat exchanger models, a volumetric pump model and a scroll expander model. Measured performance of the ORC prototype is presented and used to validate the ORC model. This model is finally used to investigate potential improvements of the prototype. [less ▲]

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See detailCharacterization of a scroll compressor under extended operating conditions
Cuevas, Cristian; Lebrun, Jean ULg; Lemort, Vincent ULg et al

in Applied Thermal Engineering (2010), 30

Refrigeration and air-conditioning compressors are designed to work under well-defined conditions. In some applications it is interesting to observe their performances beyond these conditions, for example ... [more ▼]

Refrigeration and air-conditioning compressors are designed to work under well-defined conditions. In some applications it is interesting to observe their performances beyond these conditions, for example in the case of a high temperature two-stage heat pump or of a cooling system working at high temperature. In this study a compressor is characterized experimentally with refrigerant R134a and through 118 tests at condensing pressures varying from 8.6 up to 40.4 bar (tsat = 33.9°C to tsat = 100.8°C) and evaporating pressures varying from 1.6 up to 17.8 bar (tsat = -15.6°C to tsat = 62.4°C). Under these conditions the compressor motor was pushed at its maximal current in several tests. This compressor’s performance is mainly characterized by its isentropic and volumetric efficiencies. It presents a maximal isentropic efficiency of 72%, corresponding to a pressure ratio of around 2.5–2.6. The volumetric efficiency decreases linearly from almost 1.0 (for a pressure ratio of 1.3) to 0.83 (for a pressure ratio of 9.7). A slight degradation of the isentropic and volumetric efficiencies is observed when the compressor supply and exhaust pressures are increased for a given pressure ratio; this could be due to an internal leakage. The compressor tests are used to identify the six parameters of a semi-empirical simulation model. After parameter identification, experimental and simulated results are in very good agreement, except for some points at high compressor power where the compressor is pushed at its maximal current. [less ▲]

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See detailDevelopment and use of equation based simulation tools to support audit of commercial buildings
Bertagnolio, Stéphane ULg; Lebrun, Jean ULg; Andre, Philippe ULg

in Proceedings of the eleventh International IBPSA Conference, Glasgow, UK (2009, July)

A series of new 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 ... [more ▼]

A series of new 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 Opportunities (ECOs). The Building-HVAC System global models presented here include simplified models of building zones and of HVAC equipment. Only a limited number of easily identifiable parameters is 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 use of these models are discussed in the present paper. Focus is also given to the calibration of the tools to the monthly utility bills. [less ▲]

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See detailTesting and validation of simulation tools of HVAC mechanical equipment including their control strategies. Part III: Validation of an air-cooled chiller model
Lemort, Vincent ULg; Lebrun, Jean ULg; Felsmann, Clemens

(2009, July)

This paper presents a semi-empirical steady-state model of an air-cooled water chiller. The first part of the paper shows how the model is built by associating a scroll compressor and two heat exchanger ... [more ▼]

This paper presents a semi-empirical steady-state model of an air-cooled water chiller. The first part of the paper shows how the model is built by associating a scroll compressor and two heat exchanger sub-models. The second part of the paper presents the parameters identification process based on published manufacturer data (for the compressor and the whole chiller models). The only encountered difficulty is the characterization of the fan control model, since information is lacking to identify its parameters. The third part of the paper presents results of an experimental investigation carried out on the same chiller integrated into an existing cooling plant. A detailed analysis of the experimental data allowed a better understanding of the chiller’s operation and a better identification of the model’s parameters (such as the models of the fan control and of the compressor staging control). Moreover, a simple but realistic model of the condenser hot gas by-pass was introduced. As a result, deviations between predictions by the model and the experimental data were considerably reduced. The model is finally found to predict the total cooling energy and the total electrical consumption over a long-term simulation period with a very good accuracy. [less ▲]

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See detailTesting and validation of simulation tools of HVAC mechanical equipment including their control strategies. Part II: Validation of cooling and heating coil models
Felsmann, Clemens; Lebrun, Jean ULg; Lemort, Vincent ULg et al

(2009, July)

This paper presents detailed information about testing and validation of cooling and heating coil models. The work has been carried out under Subtask D of the International Energy Agency’s SHC Task 34 ... [more ▼]

This paper presents detailed information about testing and validation of cooling and heating coil models. The work has been carried out under Subtask D of the International Energy Agency’s SHC Task 34/ECBCS Annex 43 (Testing and Validation of Building Energy Simulation Tools). The goal of this Subtask (Mechanical Equipment and Control Strategies) was to develop and test methods that would help evaluating, diagnosing and correcting HVAC mechanical equipment simulation software. [less ▲]

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See detailTesting and validation of simulation tools of HVAC mechanical equipment including their control strategies. Part I: Description of the validation test cases
Felsmann, Clemens; Lebrun, Jean ULg; Lemort, Vincent ULg et al

(2009, July)

This paper presents the work carried out under Subtask D of the International Energy Agency SHC Task 34/ECBCS Annex 43 (Testing and Validation of Building Energy Simulation Tools). The goal of this ... [more ▼]

This paper presents the work carried out under Subtask D of the International Energy Agency SHC Task 34/ECBCS Annex 43 (Testing and Validation of Building Energy Simulation Tools). The goal of this Subtask (Mechanical Equipment and Control Strategies) was to develop methods to help evaluating, diagnosing and correcting HVAC mechanical equipment simulation software. [less ▲]

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See detailDevelopment and validation of a condenser three zones model
Cuevas, Cristian; Lebrun, Jean ULg; Lemort, Vincent ULg et al

in Applied Thermal Engineering (2009)

A general and simple ‘‘deterministic” model of a refrigeration condenser is presented. The model assumes that the condenser can be divided into three distinct zones on the refrigerant side: the vapour de ... [more ▼]

A general and simple ‘‘deterministic” model of a refrigeration condenser is presented. The model assumes that the condenser can be divided into three distinct zones on the refrigerant side: the vapour de-superheating zone, the two-phase zone and the sub-cooled liquid zone. The model inputs are the air supply temperature, the air mass flow rate, the refrigerant supply temperature (or the over-heating), the exhaust sub-cooling and the refrigerant mass flow rate. The model is able to identify the pressures and temperatures in each zone and the corresponding heat flows. The model also gives the geometrical repartition among the zones and the pressure drop on air-side. The condenser model is validated with a total of 183 tests. Testing conditions cover a very wide domain, including pressures up to 40 bars with refrigerant R134a. The model is able to predict with a probability of 95% the condenser supply pressure within a confidence interval of +0.5 and 0.1 bar. This means a condenser power confidence interval within 200 and +100 W, which is considered here as acceptable. Refrigerant pressure drop is predicted with a higher error, but it is attributed to measuring uncertainty. On the other hand, air pressure drop is predicted with a very poor accuracy. Undoubtedly, this is due to the friction factor correlation used in this study which is not the most adequate. Here a difference of 40% is obtained. [less ▲]

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See detailDeveloppement et utilisation de modèles de simulation pour l'audit et la rénovation des bâtiments conditionnés
Bertagnolio, Stéphane ULg; Lebrun, Jean ULg; Andre, Philippe ULg

(2009, May)

Une suite d’outils de simulation de bâtiment et de système de climatisation destinés à assister l’audit et la rénovation des bâtiments commerciaux est actuellement en développement. Les outils en question ... [more ▼]

Une suite d’outils de simulation de bâtiment et de système de climatisation destinés à assister l’audit et la rénovation des bâtiments commerciaux est actuellement en développement. Les outils en question sont développés de façon à limiter le nombre de paramètres demandés à l’utilisateur et à garder une transparence totale pour ce dernier. Dans un premier temps, le développement des modèles et leur implémentation dans un solveur d’équations sont discutés. L’identification des paramètres des modèles développés est ensuite discutée et illustrée par un exemple d’application. [less ▲]

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See detailEvaluation, correction et validation de modèles de composants d'une centrale de production d'eau glacée
Lemort, Vincent ULg; Lebrun, Jean ULg

(2009, May)

Ce papier présente des outils d’évaluation, de correction et de validation des modèles de simulation d’un groupe frigorifique et d’une batterie froide. Après avoir brièvement décrit les modèles, le papier ... [more ▼]

Ce papier présente des outils d’évaluation, de correction et de validation des modèles de simulation d’un groupe frigorifique et d’une batterie froide. Après avoir brièvement décrit les modèles, le papier montre comment leurs paramètres peuvent être identifiés sur base uniquement des performances publiées par les constructeurs. Cette information est incomplète et des hypothèses rationnelles sont proposées. Les modèles sont validés par comparaison des résultats de simulations avec à ceux obtenus au moyen d’autres modèles et/ou avec des données expérimentales. Ces comparaisons conduisent finalement à encore améliorer les modèles et à en ré-ajuster les paramètres. [less ▲]

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See detailTesting and modeling a scroll expander integrated into an Organic Rankine Cycle
Lemort, Vincent ULg; Quoilin, Sylvain ULg; Cuevas, Cristian et al

in Applied Thermal Engineering (2009), 29

Organic Rankine Cycles (ORC’s) are particularly suitable for recovering energy from low-grade heat sources. This paper first presents the results of an experimental study carried out on a prototype of an ... [more ▼]

Organic Rankine Cycles (ORC’s) are particularly suitable for recovering energy from low-grade heat sources. This paper first presents the results of an experimental study carried out on a prototype of an open-drive oil-free scroll expander integrated into an ORC working with refrigerant HCFC-123. By exploiting the overall expander performance measurements, the eight parameters of a scroll expander semi-empirical model are then identified. The model is able to compute variables of first importance such as the mass flow rate, the delivered shaft power and the discharge temperature, and secondary variables such as the supply heating-up, the exhaust cooling-down, the ambient losses, the internal leakage and the mechanical losses. The maximum deviation between the predictions by the model and the measurements is 2% for the mass flow rate, 5% for the shaft power and 3 K for the discharge temperature. The validated model of the expander is finally used to quantify the different losses and to indicate how the design of the expander might be altered to achieve better performances. This analysis pointed out that the internal leakages and, to a lesser extent, the supply pressure drop and the mechanical losses are the main losses affecting the performance of the expander. [less ▲]

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See detailSimulation-assisted audit of an air conditioned building
Bertagnolio, Stéphane ULg; Lebrun, Jean ULg; Hannay, Cleide ULg et al

in Proceedings of the 8th International Conference for Enhanced Building Operation, Berlin, Germany (2008, October)

The example presented here concerns the audit of a typical, medium-size, office building erected in Brussels at the end of the sixties. This building is equipped with a classical old fashioned air ... [more ▼]

The example presented here concerns the audit of a typical, medium-size, office building erected in Brussels at the end of the sixties. This building is equipped with a classical old fashioned air conditioning system with air handling units and four-pipes induction units. In the first part of the paper, a classical audit procedure is applied. It consists in a systematic analysis of all information available, with help of very simple calculation. In the second part of the paper, an equation-based building-HVAC simulation tool is used to assist the audit. Fuel and electricity consumption are then interpreted and significant energy saving opportunities are identified. [less ▲]

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See detailNew simulation tools usable in the energy audit of HVAC systems
Lebrun, Jean ULg; Bertagnolio, Stéphane ULg

Scientific conference (2008, October)

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See detailSimulation of a building and its HVAC system with an equation solver: Application to benchmarking
Bertagnolio, Stéphane ULg; Lebrun, Jean ULg

in Building Simulation: An International Journal (2008), 1(3), 234-250

The today - availability of powerful engineering equation solvers is opening very new possibilities in technical component modelling and in system simulation. The simulation models, the “user guide” and ... [more ▼]

The today - availability of powerful engineering equation solvers is opening very new possibilities in technical component modelling and in system simulation. The simulation models, the “user guide” and the “reference guide” are all included in a same file. Reliable “reference” and “simplified” models are currently available for the building zone and for most HVAC components. Focus is given here on “simplified” models and on a simulation tool, called “Benchmark”. This tool should help an auditor to make the best use of the limited information usually available about actual fuel and electricity consumptions and to get a very first evaluation of the actual performances of a given HVAC system. An example of such use is presented. Another simulation tools and more information about the modelling of HVAC components will be presented in a further paper. [less ▲]

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See detailBuilding and HVAC system simulation with the help of an engineering equation solver
Bertagnolio, Stéphane ULg; Masy, Gabrielle; Andre, Philippe ULg et al

in Proceedings of the 3rd National conference of the IBPSA-USA, Berkeley, CA (2008, July)

A simplified Building-HVAC system model is presented here. It includes simplified models of building zone and of HVAC equipment. The simplified building zone model is based on a R and C network, whose ... [more ▼]

A simplified Building-HVAC system model is presented here. It includes simplified models of building zone and of HVAC equipment. The simplified building zone model is based on a R and C network, whose parameters are adjusted trough a frequency characteristic analysis. The implementation of the classical phenomena taking place in building dynamics is discussed. The simplified building model is compared with more detailed models, using the BESTEST procedure. The application of the presented model to the audit of commercial buildings is also discussed. [less ▲]

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See detailDevelopment of a simplified Building-HVAC System model with the help of an equation solver
Bertagnolio, Stéphane ULg; Lemort, Vincent ULg; Lebrun, Jean ULg

Conference (2008, June 25)

This seminar shows how modeling and simulation environments that are built using equation-based solvers can benefit the building energy community. Such modeling and simulation environments separate the ... [more ▼]

This seminar shows how modeling and simulation environments that are built using equation-based solvers can benefit the building energy community. Such modeling and simulation environments separate the formulation of a model’s underlying physics from its numerical solution algorithms. This allows input-output free modeling, it leads to faster model development time and it facilitates model reuse for different applications. Equation-based modeling and simulation environments are frequently used in various industrial sectors. For building energy simulation, however, they have not yet enjoyed wide-spread use. This seminar encourages discussions to understand their applicability, advantages and limitations for the building energy community. [less ▲]

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See detailHeat Pumping and Reversible Air Conditioning: How to make the best use of HVAC equipment ?
Bertagnolio, Stéphane ULg; Lebrun, Jean ULg; Andre, Philippe ULg et al

in Proceedings of the 9th International IEA Heat Pump Conference, Zurich, Switzerland (2008, May)

Detailed reference viewed: 74 (13 ULg)