<p>This diploma work on D-level is made in cooperation with Varnäsföretagen AB in Eskilstuna. The company performs contract manufactured aluminium goods. This work is a continuation on earlier diploma work in Varnäsföretagen AB. Even if the industry process consumes much energy for melting the aluminium goods, they consume a great amount of oil to warm up the building. The purpose of this work is to examine some places in the building and the process to see how much energy it is possible to recycles to the heating system and reduce the costs for heating. The places have all a big heat excess and recycling will get more acceptable thermal comfort for the staff. </p><p>Studies of efficiency, the variation in power and temperatures is made to see how much energy it is possible to recycle. Many systems could with small measures be more efficient.</p><p>A general problem for many places is that the energy is in the indoor air and has low temperature. It means that most of the energy is difficult to use in other places than for preheating of the intake air in the air handling units.</p>

This diploma work on D-level is made in cooperation with Varnäsföretagen AB in Eskilstuna. The company performs contract manufactured aluminium goods. This work is a continuation on earlier diploma work in Varnäsföretagen AB. Even if the industry process consumes much energy for melting the aluminium goods, they consume a great amount of oil to warm up the building. The purpose of this work is to examine some places in the building and the process to see how much energy it is possible to recycles to the heating system and reduce the costs for heating. The places have all a big heat excess and recycling will get more acceptable thermal comfort for the staff.  Studies of efficiency, the variation in power and temperatures is made to see how much energy it is possible to recycle. Many systems could with small measures be more efficient. A general problem for many places is that the energy is in the indoor air and has low temperature. It means that most of the energy is difficult to use in other places than for preheating of the intake air in the air handling units.

La thèse porte sur la conception et la simulation d'un réservoir de stockage solide de l'hydrogène sous forme d'hydrure de magnésium (MgH2). La particularité du réservoir conçu réside dans sa capacité à stocker l'énergie d'absorption grâce à un matériau de changement de phase (MCP). Afin de pouvoir prouver la viabilité du système, une étude portant sur le comportement de l'hydrure de magnésium compacté lors du cyclage à été effectuée. Celle-ci montre qu'après 100 cycles, les cinétiques de réaction et les taux massiques de stockage d'hydrogène ne sont pas affectés. En revanche, un changement de morphologie important a été observé puisqu'une dilatation ainsi qu'une augmentation importante de la conductivité des matériaux composites ont été relevées. L'étude du MCP révéla l'importance de certains paramètres, en particulier la conductivité thermique et l'enthalpie de fusion. Le MCP sélectionné est un alliage métallique en composition eutectique. Celui ci est bon conducteur de chaleur, présente une enthalpie de fusion élevée et une stabilité de comportement thermique au cyclage. Le réservoir construit contient 10 kg d'hydrure de magnésium co-broyé + 5 % de Graphite Naturel Expansé. Il est capable de stocker 7000 NL d'hydrogène (625 g) en 3h. L'avantage principal du réservoir est son efficacité énergétique, puisque la chaleur stockée par le MCP à l'absorption est refournie lors de la désorption. Afin de pouvoir prédire les comportements thermiques et cinétiques des prochains réservoirs basés sur cette technologie, 2 modèles numériques utilisant Matlab et Fluent ont été développés et validés. / The thesis's subject is about creation and modeling of a solid state hydrogen tank using magnesium hydride (MgH2). The main characteristic of this tank is the ability to store the heat of absorption due to the use of a Phase Change Material (PCM). In order to prove the sustainability of this system, a study, on the magnesium hydride's behavior, has been carried out. On one hand, kinetic properties and the amount of the stored hydrogen do not decrease after 100 cycles. On the other hand, a significant change on material morphology has been noticed. Indeed, a swelling and an increasing of thermal conductivity have been measured. Investigations about the MCP showed the importance of the thermal conductivity and the heat of fusion. That's why a metallic eutectic alloy has been selected. His atomic composition is Mg69Zn28Al3, he is a good thermal conductor, having a high heat of fusion, and presenting a good chemical stability during cycling. The designed tank contains 10 kg of magnesium hydride ball-milled added with Expanded Natural Graphite. It can absorb 7000 NL (625 g) of hydrogen in 3 hours and a half. On one total cycle, the energetic efficiency can be estimated to more than 70 %. At the same time, two numerical modeling have been achieved with Fluent and Matlab softwares, in order to make the design of next generation of tanks easier.