Novel Heat Sink Design Utilizing Ionic Wind for Efficient Passive Thermal Management of Grid-Scale Power Routers

This paper presents a numerical model assessing the potential of ionic wind as a heat transfer enhancement method for the cooling of grid distribution assets. Distribution scale power routers (13-37 kV, 1-10 MW) have stringent requirements regarding lifetime and reliability, so that any cooling technique involving moving parts such as fans or pumps are not viable. A new heat sink design combining corona electrodes with bonded fin arrays is presented. The model of the suggested design is solved numerically. It is predicted that applying a voltage of 5 kV on the corona electrodes could increase the heat removed by a factor of five as compared to natural convection

Application of hydrides in hydrogen storage and compression: Achievements, outlook and perspectives

Metal hydrides are known as a potential efficient, low-risk option for high-density hydrogen storage since the late 1970s. In this paper, the present status and the future perspectives of the use of metal hydrides for hydrogen storage are discussed. Since the early 1990s, interstitial metal hydrides are known as base materials for Ni – metal hydride rechargeable batteries. For hydrogen storage, metal hydride systems have been developed in the 2010s [1] for use in emergency or backup power units, i. e. for stationary applications. With the development and completion of the first submarines of the U212 A series by HDW (now Thyssen Krupp Marine Systems) in 2003 and its export class U214 in 2004, the use of metal hydrides for hydrogen storage in mobile applications has been established, with new application fields coming into focus. In the last decades, a huge number of new intermetallic and partially covalent hydrogen absorbing compounds has been identified and partly more, partly less extensively characterized. In addition, based on the thermodynamic properties of metal hydrides, this class of materials gives the opportunity to develop a new hydrogen compression technology. They allow the direct conversion from thermal energy into the compression of hydrogen gas without the need of any moving parts. Such compressors have been developed and are nowadays commercially available for pressures up to 200 bar. Metal hydride based compressors for higher pressures are under development. Moreover, storage systems consisting of the combination of metal hydrides and high-pressure vessels have been proposed as a realistic solution for on-board hydrogen storage on fuel cell vehicles. In the frame of the “Hydrogen Storage Systems for Mobile and Stationary Applications” Group in the International Energy Agency (IEA) Hydrogen Task 32 “Hydrogen-based energy storage”, different compounds have been and will be scaled-up in the near future and tested in the range of 500 g to several hundred kg for use in hydrogen storage applications.Fil: Bellosta von Colbe, Jose. Helmholtz-Zentrum Geesthacht; AlemaniaFil: Ares Fernández, José Ramón. Universidad Autónoma de Madrid; EspañaFil: Jussara, Barale. Università di Torino; ItaliaFil: Baricco, Marcello. Università di Torino; ItaliaFil: Buckley, Craig E.. Curtin University; AustraliaFil: Capurso, Giovanni. Helmholtz Zentrum Geesthacht; AlemaniaFil: Gallandat, Noris. GRZ Technologies Ltd; SuizaFil: Grant, David M.. Science and Technology Facilities Council of Nottingham. Rutherford Appleton Laboratory; Reino Unido. University of Nottingham; Estados UnidosFil: Guzik, Matylda N.. University of Oslo; NoruegaFil: Jacob, Isaac. Ben Gurion University of the Negev; IsraelFil: Jensen, Emil H.. University of Oslo; NoruegaFil: Jensen, Torben. University Aarhus; DinamarcaFil: Jepsen, Julian. Helmholtz Zentrum Geesthacht; AlemaniaFil: Klassen, Thomas. Helmholtz Zentrum Geesthacht; AlemaniaFil: Lototskyy, Mykhaylol V.. University of Cape Town; SudáfricaFil: Manickam, Kandavel. University of Nottingham; Estados Unidos. Science and Technology Facilities Council of Nottingham. Rutherford Appleton Laboratory; Reino UnidoFil: Montone, Amelia. Casaccia Research Centre; ItaliaFil: Puszkiel, Julián Atilio. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Helmholtz Zentrum Geesthacht; AlemaniaFil: Sartori, Sabrina. University of Oslo; NoruegaFil: Sheppard, Drew A.. Curtin University; AustraliaFil: Stuart, Alastair. University of Nottingham; Estados Unidos. Science and Technology Facilities Council of Nottingham. Rutherford Appleton Laboratory; Reino UnidoFil: Walker, Gavin. University of Nottingham; Estados Unidos. Science and Technology Facilities Council of Nottingham. Rutherford Appleton Laboratory; Reino UnidoFil: Webb, Colin J.. Griffith University; AustraliaFil: Yang, Heena. Empa Materials Science & Technology; Suiza. École Polytechnique Fédérale de Lausanne; SuizaFil: Yartys, Volodymyr. Institute for Energy Technology; NoruegaFil: Züttel, Andreas. Empa Materials Science & Technology; Suiza. École Polytechnique Fédérale de Lausanne; SuizaFil: Dornheim, Martin. Helmholtz Zentrum Geesthacht; Alemani

Enhanced Ambient Heat Rejection in Passive Thermal Management Systems

The combined trends of increasing computing power with the miniaturization of electronic devices brought about new challenges in terms of ambient heat rejection. The most simple and reliable ambient heat rejection method is natural air convection. However, this technique is limited in terms of the cooling power that can be dealt with. This work presents two technologies that can potentially increase the heat rejection rate to ambient air without using any moving part, thus ensuring a high reliability. The first technology considered uses ionic wind to increase the air flow through cooling passages. Ionic wind occurs when a high voltage potential is applied to an electrode with a large curvature – typically a thin wire or a needle. Due to the strong electric potential close to the electrode, a Corona discharge occurs and air molecules are ionized. The resulting ions induce an air flow through collisions with neutral molecules. In this study, the Corona current is characterized experimentally and a numerical procedure is developed to solve the electrohydrodynamics. A custom-built test bench is used to validate the numerical model experimentally. It is shown that ionic wind can increase the heat removal rate by up to 100% as compared to natural convection only. The second cooling enhancement technology considered is the addition of a chimney on top of the heat sink to increase the air flow through the cooling channels. A semi-analytical model based on thermal- and fluid equivalent resistance networks is developed. The model is validated using a commercial CFD package. Finally, a thermo-economic study is performed using genetic algorithms in order to compare the performance of both technologies versus natural convection only. A Pareto front combining the three technologies is constructed, allowing for cost-effective design decisions based on the cooling power requirements.Ph.D

Methanation reactor

The present relates to a chemical reactor comprising a catalyst bed enclosed in a reactor vessel and at least one cooling tube placed in the reactor vessel and passing through the catalyst bed, characterized in that the cooling tubes are disposed within the reactor so as to generate thermal gradients of at least 20°C/cm thereby generating hot spots throughout the reactor upon carrying out a reaction

Metal hydride compressor control device and method

The present relates to a Metal hydride compressor control method for generating a variable output pressure P_desired_outPut, comprising a first step of inflowing gaseous hydrogen into a metal hydride compartment at a constant temperature and then stopping the gaseous hydrogen inflow, a second step of heating the metal hydride to a predetermined temperature which corresponds to a temperature which passes through the α+β phase at the desired output pressure P_desired_output, a third step of opening the output connection of the compressor and keeping it at a constant pressure by regulating the temperature to keep a constant output pressure P_desired_outPut until the system completely leaves the α+β phase

Methanation reactor and method

The present relates to a chemical reactor comprising a catalyst bed enclosed in a reactor vessel and at least one cooling tube placed in the reactor vessel and passing through the catalyst bed, characterized in that the cooling tubes are disposed within the reactor so as to generate thermal gradients of at least 20°C/cm thereby generating hot spots throughout the reactor upon carrying out a reaction. The invention further relates to a methanation process

Combined hydrogen storage - compression system for the filling of high pressure hydrogen tanks

The present relates to a combined hydrogen storage-compression unit suitable for the filling of high-pressure (350 bar and beyond) hydrogen vessels. It comprises a containment vessel filled with a hydrogen storage alloy, a heating system, a cooling system and a thermal management system. The instant invention shall be connected directly to the hydrogen supply (e.g. an electrolyser) on one side and to the end consumer on the other side. Moreover, it offers the possibility for intermediate storage of at least one time the maximal quantity of hydrogen that is to be supplied at high pressure in a single step

Sample holder for accurate temperature control

The present relates to a sample holder comprising a single block (1) made of a thermally conductive material comprising at least two volumes, a reference volume (5) and a sample holding volume (4) directly machined in said single block (1), a heating means (3) and a temperature detector (2), wherein the heating means (3) is preferably embedded in the single block (1) such that the distance between the sample holding volume (4) and the heating means (3) is the same in a heat conductivity sense as the distance between the reference volume (5) and the heating means (3) and the distance between the thermocouple (2) and the heating means (3)

Parametric sensitivity in the Sabatier reaction over Ru/Al2O3 - theoretical determination of the minimal requirements for reactor activation

The methanation of carbon dioxide is an option for chemical storage of renewable energy together with greenhouse gas reutilization because it offers a product with a high energy density. The reaction CO2 + 4H(2) CH4 + 2H(2)O is performed on a Ru/Al2O3 catalyst and is strongly exothermal. For this reason, the reactor design must take into account an efficient thermal management system to limit the maximal temperature and guarantee high CO2 conversion. Additionally, the methanation reactor is subject to parameter sensitivity. This phenomenon can generate instability in the operation of a power to gas plant, due to the variability in the hydrogen production rate. Here we present a parametric study of the thermal properties of the reaction and determine the minimal feed temperature for the normal operation of a reactor. The minimal temperature required is determined by several parameters, such as pressure, space velocity and properties of the cooling system. For adiabatic reactors, the required feed temperature is 210 degrees C for a space velocity of 3000 h(-1) and a pressure of 10 bar. The space velocity strongly affects the positioning of the ignition point, causing a large variability of the feed temperature required. At the same time, the optimal working point of the reactor is at the minimal activation temperature. The properties of cooled reactors are elucidated, showing how the interrelationship between cooling and feed temperature makes the management of this class of reactors more challenging. On the base of the modelling results, we propose a reactor configuration that adjusts the thermodynamic limitations and respects the minimal requirements for reaction ignition, allowing a more stable operation and avoiding the functioning at excessive temperature