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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 detailDesigning large-scale CO2 capture units with assessment of solvent degradation
Léonard, Grégoire ULg; Crosset, Cyril; Dumont, Marie-Noëlle ULg et al

in Energy Procedia (2014), 63

Solvent degradation is one of the main operational drawbacks of post-combustion CO2 capture with amine solvents. Although the different degradation mechanisms have been largely studied in recent years, it ... [more ▼]

Solvent degradation is one of the main operational drawbacks of post-combustion CO2 capture with amine solvents. Although the different degradation mechanisms have been largely studied in recent years, it is still impossible to predict the solvent losses and the emissions of degradation products that may occur in a CO2 capture plant depending on its size and on its operating conditions. In the present work, we experimentally study the degradation of MEA monoethanolamine) under accelerated conditions implying high temperature, continuous gas feed and vigorous agitation. A special focus is set on the oxidative degradation of MEA, which is studied in the absence of CO2. Based on the experimental results, we propose a kinetic model to describe both MEA oxidative and thermal degradation pathways. The degradation kinetics is then included into a global model of the CO2 capture process, enabling solvent losses and emissions of degradation products to be predicted as a function of the process operating conditions. The predicted MEA loss is in the same order of magnitude as reported in degradation measurements from pilot plants, although lower by a factor 3. This kind of model assessing solvent degradation could and should be used for the design of large-scale CO2 capture plants in order to simultaneously consider the energy consumption of the process and its environmental impact related to the emissions of degradation products and amine solvent. Further developments shall consider the effect of SOx, NOx and dissolved metals on MEA degradation. [less ▲]

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See detailSimulation of a vertical ground heat exchanger as low temperature heat source for a closed adsorption seasonal storage of solar heat
Hennaut, Samuel ULg; Thomas, Sébastien ULg; Davin, Elisabeth ULg et al

in Energy Procedia (2014), 48

Get It @ ULg(opens in a new window)|View at Publisher| Export | Download | More... Energy Procedia Volume 48, 2014, Pages 370-379 2nd International Conference on Solar Heating and Cooling for Buildings ... [more ▼]

Get It @ ULg(opens in a new window)|View at Publisher| Export | Download | More... Energy Procedia Volume 48, 2014, Pages 370-379 2nd International Conference on Solar Heating and Cooling for Buildings and Industry, SHC 2013; Freiburg; Germany; 23 September 2013 through 25 September 2013; Code 104547 Simulation of a vertical ground heat exchanger as low temperature heat source for a closed adsorption seasonal storage of solar heat (Conference Paper) Hennaut, S.a , Thomas, S.a, Davin, E.a, Skrylnyk, A.b, Frère, M.b, André, P.a a University of Liège, Building Energy Monitoring and Simulation, Avenue de Longwy 185, 6700 Arlon, Belgium b University of Mons, Energy Research Cente, Boulevard Dolez 31, 7000 Mons, Belgium View references (9) Abstract This paper deals with the simulation of a vertical geothermal heat exchanger as low temperature heat source for a closed adsorption seasonal heat storage. The seasonal storage should allow reaching a nearly 100 % solar fraction for space heating of a "low energy" building". The selected adsorbent and adsorbate are respectively bromide strontium and water. The studied system, including the building and the ground exchanger, is simulated using the dynamic simulation software TRNSYS. Results show that expected performances are reached with a borehole of 100 m. The evaporation temperatures computed are really close to 0°C which might cause some problems. But an advanced research would maybe impose a deeper borehole to avoid cooling the ground on the long term. [less ▲]

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See detailExperimental study and modeling of sorption isotherms of Kabar Sid El Cheikh Capparis spinosa L. from Bechar (South west Algeria)
Said, Bennaceur; Belkacem, Draoui; Bennamoun, Lyes ULg et al

in Energy Procedia (2012), 18

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See detailEffects of hydrogen partial pressure on fermentative biohydrogen production by a chemotropic Clostridium bacterium in a new horizontal rotating cylinder reactor
Beckers, Laurent ULg; Hiligsmann, Serge ULg; MAsset, Julien et al

in Energy Procedia (2012)

In order to produce fermentative biohydrogen at high yields and production rates, efficient bioreactors have to be designed. A new reactor called anaerobic biodisc reactor allowed the production of ... [more ▼]

In order to produce fermentative biohydrogen at high yields and production rates, efficient bioreactors have to be designed. A new reactor called anaerobic biodisc reactor allowed the production of biohydrogen from glucose with the selected Clostridium sp. strain at high yields (2.49 molH2•molglucose-1) and production rates (598 mlH2•medium-1•h-1). The bacteria were fixed on a rotating support enabling efficient gas transfer from the liquid to the phase. It allowed the metabolism of the bacteria to produce more hydrogen. Moreover, an increase of the total pressure 0.18 bar lowered the yields of 19.5% while a decrease of 0.11 bar increased the yields of 7%. Our work concludes on the importance of providing good liquid to gas transfers in the biohydrogen-producing reactors. [less ▲]

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See detailExperimentation and Simulation of a Small-Scale Adsorption Cooling System in Temperate Climate
Thomas, Sébastien ULg; Hennaut, Samuel ULg; Maas, Stefan et al

in Energy Procedia (2012), 30

This paper focuses on the analysis of the operation of a solar cooling system based upon an adsorption chiller. The air-conditioned building studied is a laboratory located in a temperate climate region ... [more ▼]

This paper focuses on the analysis of the operation of a solar cooling system based upon an adsorption chiller. The air-conditioned building studied is a laboratory located in a temperate climate region (Belgium). The monitoring reveals thermal and electrical coefficient of performance (COP) of the cooling system for different time scale (10s to 1 month). The whole system including solar collectors, adsorption machine, recooling unit and hot storage is simulated. The models are then confronted to the measurements. Measurement period is shared between 2011 and 2012. Enhancements have been achieved during winter 2011 to have a more efficient system operation. The aim of this experimental work is to describe, for both measurement periods, the influence of operating conditions on the energy efficiency (thermal behavior and electrical consumption). On the simulation point of view, the main objective is to find accurate models for all the components. The adsorption chiller model is not yet precise enough to evaluate the performance of solar cooling in other conditions. [less ▲]

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