Modeling and simulation of an air conditioning chilled water system

(2006, December)

This paper is giving an overview of problems encountered and solutions available for the simulation of an air conditioning system. Focus is given on the chilling water subsystem (from the chiller to the ... [more ▼]

This paper is giving an overview of problems encountered and solutions available for the simulation of an air conditioning system. Focus is given on the chilling water subsystem (from the chiller to the cooling coil). Main component simulation models (chillers, pumps, piping, valves, cooling coils and fans) are presented; they are tuned on manufacturer’s catalogue data. The way of integrating these models into a global HVAC system simulation is illustrated thanks to one example: the simulation of (a part of) a real chilled water loop, which is submitted to an exhaustive monitoring. Cooling demands and corresponding energy consumptions are systematically simulated and measured on one-minute time basis. This provides the opportunity for a global checking of the simulation by comparing simulated and measured cooling coil outputs. Further work should also include comparisons on chiller consumptions. [less ▲]

A contribution to the audit of an air-conditioning system: modeling, simulation and benchmarking

(2006, December)

This paper intends to show how benchmarks can help in the audit of a HVAC system and how these benchmarks can be generated. The work presented is part of the European “AUDITAC” project. How can an auditor ... [more ▼]

This paper intends to show how benchmarks can help in the audit of a HVAC system and how these benchmarks can be generated. The work presented is part of the European “AUDITAC” project. How can an auditor declare that a given HVAC is “consuming too much”? He can’t make any judgment, if not having some reference, i.e. some “benchmarks” available. Focus is given here to cooling regime, but even then, heating cannot be forgotten (for example, the remaining heating demand can be satisfied thanks some recovery on the condensers of the chillers). The dramatic question is: what should be the consumption(s) for such a building, in such a climate, with such occupancy, such internal loads and such actual indoor environment? Better than to look for a (very hypothetical) global weather index, similar to heating degree-days, it seems more rational to run a simulation model on a few thousands of hours, corresponding to one (or to several) cooling season(s). Current performances of simulation tools make this approach very expedient. The climate can then be considered as it is, without any simplification. The main simplification is still welcome on the system (building + HVAC) side, in order to get calculation robustness, easy understanding and easy parameter identification. In this perspective, the building has to be subdivided in a very limited number of zones and only a few components of the HVAC system have to be included in the simulation model, with as simple as possible control strategies. [less ▲]

From model validation to production of reference simulations: how to increase reliability and applicability of building and HVAC simulation models

(2006, December)

Validation of simulation models appears from a long time as a key issue in order to promote a more intensive and more efficient use of simulation models in the field of building and HVAC simulation. IEA ... [more ▼]

Validation of simulation models appears from a long time as a key issue in order to promote a more intensive and more efficient use of simulation models in the field of building and HVAC simulation. IEA Annex 34/43 originally targeted a number of specific applications where a more advanced validation was required: ground coupling problems, multizone building, shading, day lighting and cooling load interaction, HVAC components and ventilated facades. These validation exercises were built on the large methodological experience obtained in previous projects and address sometimes very fundamental problems of heat transfer in buildings. Consulting engineers and practitioners might see these exercises as a bit too far from their objectives and it is the reason why an additional activity was proposed with the specific aim of producing, based upon the results of the validation of models, a set of reference simulations. These applications cover a range of building types (residential, commercial) and systems (production, distribution emission) and run in a variety of climates. The paper will describe how models dedicated to these applications were developed, starting from validation results, going through the selection and consolidation of simulation hypothesises and ending with a number that might be considered as reference for the concerned applications. The paper will concentrate on models required by a residential building application (multizone building equipped with a heat pump or a condensing boiler). Simulations make use of both EES and TRNSYS software and both software are applied in parallel as far as possible in the different applications in order to get a better judgment of their potential advantages and drawbacks. The use of reference simulations in view of qualifying normative methods currently in development in the frame of the European Energy Performance in Buildings Directive is also addressed and demonstrated in the paper. [less ▲]

Le cas clinique du mois. Syndrome malin des neuroleptiques et paralysie generale

in Revue Médicale de Liège (2006), 61(12), 807-11

Described in 1960 by Jean Delay in relation to the use of haloperidol, neuroleptic malignant syndrome remains relatively rare, and poorly known by the medical profession. The emergence of the atypical ... [more ▼]

Described in 1960 by Jean Delay in relation to the use of haloperidol, neuroleptic malignant syndrome remains relatively rare, and poorly known by the medical profession. The emergence of the atypical antipsychotic agents and preventive measures which have become general in recent years in hospital departments using dopamine receptor antagonists has not altered the prognosis, which remains potentially fatal in approximately a quarter of cases. This article proposes a descriptive summary of this syndrome in terms of clinical and biological diagnostics as well as of evolution, epidemiology, differential diagnosis and treatment. It describes the case of a patient affected by general paralysis having developed a neuroleptic malignant syndrome, thus the hypothesis what the neuroleptic malignant syndrome preferentially arises in subjects having underlying organic or metabolic problems and provides food for thought regarding the main medical and psychiatric overlaps, the use of dopaminergic agents and the behaviour to be adopted when dealing with a patient presenting with inaugural psychiatric symptomatology. [less ▲]

A numerical comparison of control strategies applied to an existing ice storage system

in Energy Conversion and Management (2006), 47(20), 3619-3631

While ice storage systems are designed according to a defined strategy for warm day loads, it is interesting to consider other conventional control strategies for mid-season day loads. Three different ... [more ▼]

While ice storage systems are designed according to a defined strategy for warm day loads, it is interesting to consider other conventional control strategies for mid-season day loads. Three different charging-discharging control strategies are applied to an existing cooling plant and compared in terms of operating costs and energy consumption. A cooling plant model is built. A time stage equal to 15 min is considered to simulate numerically a whole charging-discharging process and compare the different control strategies. These simulations take into account existing technical constraints and set points. EES software is used. The operating costs of the cooling plant are evaluated by taking into account both the energy and the demand cost rate. It is shown that an ice storage system can allow savings of operating costs. However, they can increase energy consumption. (c) 2006 Elsevier Ltd. All rights reserved. [less ▲]

Entre méfiance et intégration. Les germanophones dans l'armée belge (1920-1955)

in Cahiers Belges d'Histoire Militaire (2006), 4

Assessment of trophic relationships between symbiotic tropical ophiuroids using C and N stable isotope analysis

in Journal of the Marine Biological Association of the United Kingdom (2006), 86(6), 1443-1447

Analyses of the natural abundance of carbon and nitrogen stable isotopes were performed to investigate the feeding habits of two ophiurolds, Ophiomastix venosa and Ophiocoma scolopendrina, and to assess ... [more ▼]

Analyses of the natural abundance of carbon and nitrogen stable isotopes were performed to investigate the feeding habits of two ophiurolds, Ophiomastix venosa and Ophiocoma scolopendrina, and to assess the potential benefit obtained by the symbiotic Ophiomastix venosa juveniles. A tracer experiment was also carried Out to clarify the contribution of algae to the nitrogen uptake amongst the tested ophiurolds. Our results suggest that Ophiocoma scolopendrina adults occupy a higher position in the food web than Ophiomastix venosa and mainly feed on neuston. In contrast, O. venosa adults feed on the alga Sargassum densifolium, and on organic matter associated with sediment. Free juveniles and symbiotic juveniles of O. venosa have intermediate PC values between both adult species. The high proportion of C-13 in the symbiotic juveniles compared to the one in their conspecific adults indicates that their diet slightly differs from the latter and is closer to that of Ophiocoma scolopendrina. This raises the hypothesis that symbiotic juveniles steal neuston front their associated host, O. scolopendrina. [less ▲]

Autobiographical memory in non-amnesic alcohol-dependent patients

in Psychological Medicine (2006), 36(12), 1707-1715

Background. Chronic alcohol abuse is associated with a wide range of cognitive deficits. However, little is known about memory for real-life events (autobiographical memory) in non-amnesic alcoholic ... [more ▼]

Background. Chronic alcohol abuse is associated with a wide range of cognitive deficits. However, little is known about memory for real-life events (autobiographical memory) in non-amnesic alcoholic patients. The purpose of this study was to investigate (a) non-amnesic alcoholics' ability to recall specific autobiographical memories and (b) their subjective experience when they access specific memories.Method. Twenty non-amnesic (without Korsakoff syndrome) recently detoxified alcoholics and 20 healthy controls completed the Autobiographical Memory Test (AMT), which assesses the frequency of specific (versus general) memories recalled in response to cue words, and the Memory Characteristics Questionnaire (MCQ), which assesses subjective experience (e.g. the amount of sensory and contextual details experienced) when remembering specific events.Results. Alcoholic patients recalled specific memories less frequently and general memories more frequently than healthy controls. Nevertheless, when a specific past event was accessed, alcoholic patients subjectively experienced as many sensory and contextual details as controls.Conclusions. These findings suggest that non-amnesic alcoholics have difficulties strategically accessing event-specific autobiographical knowledge, which might result from changes in frontal lobe function that are associated with alcoholism. [less ▲]

Rapport 2 projet FIRST DEI IMOBIOSE

Report (2006)

Le projet FIRST DEI IMOBIOSE est financé par la région wallonne et en partenariat avec la société Meurens Natural. Ce projet a pour but de produire des sirops d’isomaltooligosaccharides prébiotiques à ... [more ▼]

Le projet FIRST DEI IMOBIOSE est financé par la région wallonne et en partenariat avec la société Meurens Natural. Ce projet a pour but de produire des sirops d’isomaltooligosaccharides prébiotiques à partir de sirops de céréales et ce dans le respect du cahier des charges biologique, mais également de les caractériser d’un point de vue de leur composition et de leurs effets sur la santé. [less ▲]

Automates et vérification

in Encyclopédie de l'informatique et des systèmes d'information (2006)

La vérification de programmes consiste à analyser les comportements possibles de programmes en vue de déterminer s’ils seront toujours conformes à ce qui est attendu. Pour ce faire, les caractéristiques ... [more ▼]

La vérification de programmes consiste à analyser les comportements possibles de programmes en vue de déterminer s’ils seront toujours conformes à ce qui est attendu. Pour ce faire, les caractéristiques souhaitées des comportements sont exprimées formellement et confrontées, par des techniques mathématiques rigoureuses, à l’ensemble des comportements du programme à analyser. Dans ce contexte, les automates jouent un triple rôle. Tout d’abord, ils sont fréquemment utilisés en tant que langage de programmation simplifié pour décrire les programmes à analyser. Ensuite, ils servent de formalisme de description de propriétés de comportements, soit directement, soit par traduction à partir d’un langage logique. Finalement, ils s’avèrent très utiles en tant que formalisme de description d’ensembles infinis de valeurs. [less ▲]