In the EU funded BRAVA project, technologies for a Fuel Cell based Power Generation System aviation are being developed. this paper, test results demonstrator novel two-phase pumped cooling system with 20 kW capacity presented. This uses evaporation of liquid to remove waste heat from sources. Several concepts have been tested demonstrator, including ‘no accumulator’ concept, which offers large mass reduction compared conventional systems. Also, can be rotated, and influence orientation has tested.

Strongly vertically shaken granular matter can display a density inversion: A high-density cluster of beads is elevated by dilute gaslike layer fast underneath ("granular Leidenfrost effect"). For even stronger shaking the state becomes unstable and convection rolls emerge. This transition resembles classical onset in fluid heated from below at some critical Rayleigh number. The same seen molecular dynamics (MD) simulations material. strength for be calculated linear stability analysis...

Hydrogen-powered fuel cells are the preferred energy source for electric aircraft. However, aircraft applications, it is of upmost importance to reduce mass cell system. A considerable amount total system due cooling In this paper, analysis a 2 MW cell-powered discussed. detailed comparison made between conventional liquid with ethylene glycol–water (EGW) and novel two-phase that uses evaporation remove waste heat from cells. For system, several refrigerants were analyzed, methanol resulted...

In the EU-funded BRAVA project, technologies for a fuel cell-based power generation system aviation are being developed. this paper, test results demonstrator of novel two-phase pumped cooling with 20 kW capacity presented. This uses evaporation liquid to remove waste heat from sources. Several concepts have been tested demonstrator, including ‘no accumulator’ concept, which offers large mass reduction compared conventional systems. Additionally, can be rotated, and influence orientation has tested.

Inverse Chladni patterns, i.e., grains collecting at the antinodes of a resonating plate, are traditionally believed to occur only when particles small enough be carried along by ambient air. We now show---theoretically and numerically---that air currents not mechanism leading inverse patterns: When acceleration plate does exceed $g$, will always roll antinodes, irrespective their size, even in absence also explain why this effect has hitherto escaped detection standard experiments.

Experiments and computational simulations are carried out to study the behavior of a granular column in silo whose walls able vibrate horizontally. The is brought steady fluidized state it behaves similar hydrostatic system. We dynamics discharge through openings at bottom order search for Torricelli-like behavior. show that flow rate scales with wall induced shear rate, high rates, bed indeed discharges viscous fluid.

Abstract When very light particles are sprinkled on a resonating horizontal plate, inverse Chladni patterns formed. Instead of going to the nodal lines where they would form standard pattern, dragged antinodes by air currents induced vibration plate. Here we present detailed picture mechanism using numerical simulations involving both and air. Surprisingly, time-averaged Eulerian velocity, commonly used in these type problems, does not explain motion particles: it even has opposite...

We report on numerical simulations of a vibrated granular bed including the effect ambient air, generating famous Faraday heaps known from experiment. A detailed analysis forces shows that are formed and stabilized by airflow through while gap between vibrating bottom is growing, confirming pressure gradient mechanism found experimentally Thomas Squires [Phys. Rev. Lett. 81, 574 (1998)], with addition partly generated isobars running parallel to surface bed. Importantly, also explain heaping...

The thermal performance and operating modi of a flat-plate closed-loop pulsating heat pipe (PHP) are experimentally observed. PHP is manufactured through computer numerical controlled milling vacuum brazing stainless steel 316 L. Next to plain PHP, also one that promotes fluid circulation passive Tesla-type valves was developed. Each channel has 2 × mm2 square cross section, in total, 12 parallel channels fit within the 50 200 effective area. During experimental investigation, power input...

This paper explores the pumping characteristics and behaviour of a thermally driven self-oscillating pump. The pump consists single wickless capillary tube with circular cross-section. is closed at one end has T-section two check valves other to provide for directional flow. An experimental setup was built investigate output mass flow pressure head During experiments, performance had negative influence on To determine this influence, video analysis fluid oscillation without conducted...

When a layer of granular material is vertically shaken, the surface spontaneously breaks up in landscape small Faraday heaps that merge into larger ones on an ever increasing time scale. This coarsening process studied linear setup, for which average life span transient state with N shown to scale as N-3. We describe this by set differential equations peak positions; calculated evolution excellent agreement both experiments and simulations. The same model explains observational fact number...

J. van Es, A. Pauw, H.J. Gerner, Thermal Control Group, Space Division, National Aerospace Laboratory, 8316 PR Marknesse Johannes.van.Es@nlr.nl, The Netherlands and E. Laudi Laboratory Study of Radiation Effect on Materials for application, 05100 Terni, Italy C.Gargiulo Instituto Nazionale di Fisica Nucleare Sezione Roma c/o Dipartimento Universita' degli Studi 00185 – Z.He Center Technology, Sun Yat-Sen University, 519082 Zhuhai, People’s Republic China B. Verlaat NIKHEF, Institute...

Abstract Currently, the amount of electrical power that is available for CubeSat’s very small and this reason, simple thermal conductance through frame CubeSat sufficient most missions. However, deployable solar panels have been developed recently peak powers up to 40W can now be generated. This higher generated results in more waste heat potentially too high temperatures inside CubeSat. For use water-filled pipes studied, since these are cheap, widely commercially available, bent desired...

When a layer of sand is vertically shaken, the surface spontaneously breaks up in landscape small conical "Faraday heaps," which merge into larger ones on an ever increasing time scale. We propose model for heap dynamics and show analytically that mean lifetime transient state with N heaps scales as N(-2). there abundance sand, such vibrating plate always remains completely covered, this means average diameter grows t(1/2). Otherwise, when less plentiful parts get depleted during coarsening...

In the EU funded BRAVA project, technologies for a Fuel Cell based Power Generation System aviation are being developed. this paper, analysis of 2 MW cooling system is dis-cussed. A comparison made between conventional liquid with Ethylene Glycol Water (EGW) and novel two-phase system, which uses evaporation liq-uid to remove waste heat from fuel cells. The mass EGW 35% higher than methanol accumulator 2.4 times metha-nol without accumulator.