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See detailMODELLING OF A DOMESTIC GAS-FIRED CONDENSING BOILER
Ballant, Adrien; Makaire, Danielle ULg; Ngendakumana, Philippe ULg

Scientific conference (2008, May)

Within the actual context of energy savings and pollutant emissions reduction, installing condensing boilers becomes indispensable because of their high efficiency compared to conventional boilers. A ... [more ▼]

Within the actual context of energy savings and pollutant emissions reduction, installing condensing boilers becomes indispensable because of their high efficiency compared to conventional boilers. A simulation model predicting boiler performances and condensing rate in the boiler heat exchanger is very valuable. The model developed within this work is a one-dimension model of a domestic gasfired condensing boiler. The aim of the model is to know whether or not the boiler works in good condensing conditions. It gives a better understanding of using and installation requirements of condensing boilers. The structure of the model is similar to a conventional boiler model [1] with a combustion chamber and a dry heat exchanger (HX1), at which a wet heat exchanger (HX2) is added (Figure 1). The calculation consists of evaluating combustion gas temperature and gas composition after the dry heat exchanger. Then, retrievable energy from the flue gas is calculated for a fixed geometry and efficiency of wet heat exchanger and for a fixed return water temperature. The heat transfer coefficient in the wet heat exchanger is calculated according to Liang et al. [2] . The influence of different parameters on condensing performances are analysed: excess air, return water temperature and flue gas mass flow rate for different heat output power. The model has been validated with measurements on a test bench equipped with a 24 kW gas-fired condensing boiler. The test bench is represented on Figure 2. [less ▲]

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See detailMODELLING OF A DOMESTIC GAS-FIRED CONDENSING BOILER
Makaire, Danielle ULg; Ngendakumana, Philippe ULg

Conference (2008, September)

Nowadays, condensing technology is widely used in domestic heating. This paper presents a model that simulates the performance in steady-state regime of a domestic gas-fired condensing boiler. The model ... [more ▼]

Nowadays, condensing technology is widely used in domestic heating. This paper presents a model that simulates the performance in steady-state regime of a domestic gas-fired condensing boiler. The model is similar to a conventional boiler model with a dry heat exchanger at which a wet heat exchanger is added to simulate the heat recovered by condensation. Experimental parameters are used to simulate the different components. The model has been applied to a 24 kW gas-fired condensing boiler test bench available in the laboratory. According to the experimental results (at full load), the model predicts correctly the thermal efficiency of the boiler. Indeed, calculated values are in good agreement with measured values. [less ▲]

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Peer Reviewed
See detailModelling of Accessibility Fields
Donnay, Jean-Paul ULg; Ledent, Philippe

in Proceeding of the First Joint European Conference on Geographical Information (1995)

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See detailModelling of agricultural diffuse pollution and mitigation measures effectiveness inWallonia (Belgium)
Sohier, Catherine ULg; Deraedt, Deborah ULg; Degré, Aurore ULg

in Geophysical Research Abstracts (2012), 14(EGU2012), 9672

Implementation of European directives in the environmental field and, specially, in the water management field, generates a request from policy-makers for news tools able to evaluate impact of management ... [more ▼]

Implementation of European directives in the environmental field and, specially, in the water management field, generates a request from policy-makers for news tools able to evaluate impact of management measures aiming at reducing pressures on ecosystems. In Wallonia (Southern Region of Belgium), the Nitrate Directive (EEC/676/91) was transposed into the “Walloon action plan for nitrogen sustainable management in agriculture” (PGDA1) in 2002. In 2007, a second plan was launched to reinforce some topics (PGDA2). Furthermore, the goal of “good quality” of surface waters and groundwater imposed by the Water Framework Directive poses new challenges in water management. In this context, a “soil and vadose” hydrological model is used in order to evaluate diffuse pollutions and efficiency of mitigation measures. This model, called EPICgrid, has been developed at catchment scale with an original modular concept on the basis of the field scale “water-soil-plant” EPIC model (Williams J.R., Jones C.A., Dyke P.T. (1984). A modelling approach to determining the relationship between erosion and soil productivity. Transactions of the ASAE. 27, 129-144). The model estimates, for each HRU identified into a 1km2 grid, water and nutrients flows into the plant-soil-vadose zone system (Sohier C., Degré A., Dautrebande S. (2009). From root zone modelling to regional forecasting of nitrate concentration in recharge flows – The case of the Walloon Region (Belgium). Journal of Hydrology, Volume 369, Issues 3-4, 15 May 2009, Pages 350-359). The model is used to make prospective simulations in order to evaluate the impact of measures currently performed to reduce the effect of diffuse pollution on water surface quality and groundwater quality, at regional scale. Response of the soil-vadose zone to agricultural practices modification is analyzed for the deadlines of the Water Framework Directive: 2015, 2021 and 2027, taking into account two climatic scenarios. Simulations results showed that actual measures are not sufficient in some areas and that new actions are necessary. The EPICgrid model was also used to evaluate effectiveness of further measures that could be implemented in order to reduce agricultural diffuse pollution. The increasing of catch crops in vulnerable zones has shown a limited impact in theWalloon context. The modifications of agricultural practices such as crop rotations or mineral fertilizing amounts have shown a more significant impact on water quality. Furthermore, the farmers’ practices are evaluated each year by a measuring campaign of the soil nitrogen residue after harvest. These data allow us to improve the representativeness of the EPICgrid model in areas in which agricultural practices largely differs from regional statistics. [less ▲]

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See detailModelling of an air condenser working in critical zone for engine cooling by refrigerant loop
Cuevas, Cristian; Winandy, Eric; Lebrun, Jean et al

in 6th Edition of Vehicle Thermal Management Systems (VTMS) Conference (2003, May)

A general and simple model of a condenser for engine cooling by refrigeration loop is presented. The model assumes that the condenser is divided into three distinct zones on the refrigerant side: the ... [more ▼]

A general and simple model of a condenser for engine cooling by refrigeration loop is presented. The model assumes that the condenser is divided into three distinct zones on the refrigerant side: the vapor superheated zone, the two-phase zone and the sub-cooled liquid zone. The model inputs are the dry bulb air supply temperature, the air mass flow rate, the refrigerant supply over-heating, the sub-cooling and the refrigerant mass flow rate. The model is able to give mainly the pressure and temperature in each zone and, of course also, the heat flow and the exhaust enthalpy. The model gives also the geometrical repartition or area percentage of each zone. Adjustable coefficients are used with each correlation to fit the experimental results. An example of identification and validation is presented. The condenser has been tested up to 40 bar with R134a and the model accuracy is within ±2K in condensing temperature prediction. [less ▲]

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See detailMODELLING OF BACTERIAL SULPHATE REDUCTION IN ANAEROBIC PONDS : KINETIC INVESTIGATIONS
Harerimana, Casimir ULg; Vasel, Jean-Luc ULg; Jupsin, Hugues ULg et al

in Australian Water Association (2011)

The aim of the study was first to develop a simple and practical model of anaerobic digestion including sulphate-reduction in anaerobic ponds. The basic microbiology of our model consists of three steps ... [more ▼]

The aim of the study was first to develop a simple and practical model of anaerobic digestion including sulphate-reduction in anaerobic ponds. The basic microbiology of our model consists of three steps, namely, acidogenesis, methanogenesis, and sulphate reduction. This model includes multiple reaction stoichiometry and substrate utilization kinetics. The second aim was to determine some kinetic parameters associated with this model. The values of these parameters for sulfidogenic bacteria are used in the anaerobic pond model to describe the sulphate reduction processes and to evaluate the risk of odour generation. [less ▲]

Detailed reference viewed: 84 (4 ULg)
Peer Reviewed
See detailModelling of beam-to-column joints for the design of steel building frames.
Maquoi, René ULg; Jaspart, Jean-Pierre ULg

in Proceedings of the Constructional steel design conference (1992)

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See detailThe modelling of catalytic trickle-bed reactors
Crine, Michel ULg; Marchot, Pierre ULg

in Chemical Engineering of Gas-Liquid-Solid Reactions (1979)

Detailed reference viewed: 1 (1 ULg)
See detailModelling of Cellular Dynamics
Bullinger, Eric ULg

Conference (2005, September 01)

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See detailModelling of contact between stiff bodies in automotive transmission systems
Virlez, Geoffrey ULg; Bruls, Olivier ULg; Poulet, Nicolas et al

in Fisette, Paul; Samin, Jean-Claude (Eds.) Multibody Dynamics: Computational Methods and Applications (2013)

Many transmission components contain moving parts, which can come into in contact. For example, the TORSEN differentials aremainly composed of gear pairs and thrust washers. The friction involved by ... [more ▼]

Many transmission components contain moving parts, which can come into in contact. For example, the TORSEN differentials aremainly composed of gear pairs and thrust washers. The friction involved by contacts between these two parts is essential in the working principle of such differentials. In this chapter, two different contact models are presented and exploited for the modelling of differentials. The former uses an augmented Lagrangian technique or a penalty method and is defined between two flexible bodies or between a rigid body and a flexible structure. The second contact formulation is a continuous impact modelling based on a restitution coefficient. [less ▲]

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See detailModelling of dual porosity media: comparisons of different techniques and evaluation of the impact on plume transport simulations
Brouyère, Serge ULg; Dassargues, Alain ULg; Therrien, René et al

in Stauffer, F.; Kinzelbach, W.; Kovar, K. (Eds.) et al Calibration and Reliability in Groundwater Modelling: Coping with Uncertainty (2000)

Detailed reference viewed: 34 (16 ULg)
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See detailModelling of electromagnetic waves in periodic media with finite elements
Nicolet, A.; Guenneau, S.; Geuzaine, Christophe ULg et al

in Journal of Computational & Applied Mathematics (2004), 168

Detailed reference viewed: 22 (3 ULg)
Peer Reviewed
See detailModelling of electromagnetic waves in periodic media with finite elements
Nicolet, A.; Guenneau, S.; Geuzaine, Christophe ULg et al

in 2nd international conference on advanced computational methods in engineering, ACOMEN 2002 (2002)

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See detailModelling of Forest Trees Autecology. An applied research at the Walloon Region scale (Belgium)
Ridremont, François ULg; Claessens, Hugues ULg; Lejeune, Philippe ULg et al

Poster (2010, January 12)

Three reasons have urged the Walloon Forest Administration (Walloon Public Service) on to solicit the help of forest researchers to bring practical responses to the adaptation of its current forests ... [more ▼]

Three reasons have urged the Walloon Forest Administration (Walloon Public Service) on to solicit the help of forest researchers to bring practical responses to the adaptation of its current forests management: (i) the progression of research in applied autecology, (ii) the development of software for the management and the analysis of georeferenced data (GIS technologies) and, (iii) the awareness of the potential negative impacts of climate change on forests. To answer to this request, this research aims to model the autecology of the main forest tree species at the Walloon Region scale (Beech, Oak, Norway Spruce, Douglas-fir and valuable broadleaves species). The results will be used to update current practical tools to assess the adequacy of forest tree species on sites, especially in the climate change context. The research is built into three main steps: • update the autecology knowledge for the targeted forest tree species through a state of the art; • compile and create different ecological parameters that can explain the major part of trees growth such as climatic, topographic, geologic, edaphic and phytosociological data gathered from forest plots or geodatabases. In the context of climate change, a particular attention will be brought on bioclimatic and soil moisture conditions because of their narrow link with the potential risk of trees ecophysiological stress; • model tree species reaction to environmental conditions with tree growth indicators. Three types of indicators with different spatio-temporal scales are foreseen: stand site index (30-50 years), periodic diameter growth (5-10 years) and tree-ring growth (1-3 years). The use of these three scales is justified by the interest presented by their cross-validations which are necessary for an accurate extrapolation of results to the entire region. Results should indicate the tree species behaviour, especially towards stress conditions. The integration of climatic data, provided by global climate models based on IPCC's climate scenarios, in autecological models could be used to assess the behaviour of forest stands in future climate conditions. From those results, we expect to identify and assess accurately the risky “sites-species pairs” to avoid in the context of a sustainable silviculture. Finally, results will be used to provide autecological synthesis and practical tools to help forest managers and foresters to identify the best “site-species pairs” (tree-site adequacy maps, sites catalogue and computer platform). [less ▲]

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See detailModelling of Forest Trees Autecology. An applied research at the Walloon Region scale (Belgium).
Ridremont, François ULg; Claessens, Hugues ULg; Lejeune, Philippe ULg et al

in Hallet, Vincent; Vanclooster, Marnik (Eds.) ENVITAM and UNITER : PhD Student Day 2010 Proceedings (2010, January 12)

Detailed reference viewed: 34 (13 ULg)