Marcos Rojas-Cárdenas

Marcos Rojas-Cárdenas
Clément Ader Institute | ICA · Modelling of Mechanical Systems and Microsystems Group

Assistant Professor, PhD

About

19
Publications
4,364
Reads
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213
Citations
Citations since 2016
10 Research Items
173 Citations
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20162017201820192020202120220102030
Additional affiliations
September 2014 - present
Institut National des Sciences Appliquées de Toulouse
Position
  • Professor (Assistant)
Description
  • Fluid Mechanics, Heat Transfer, Thermodynamics
September 2014 - present
Clément Ader Institute
Position
  • Professor (Assistant)
Description
  • Gas Flows for Microfluidic Applications - Molecular Tagging Velocimetry
September 2009 - September 2012
Aix-Marseille Université
Position
  • PhD Student

Publications

Publications (19)
Article
Full-text available
A thermal transpiration flow through a single rectangular micro-channel was studied experimentally for various gas species, including all rare gases, in order to investigate the influence of gas species on the flow properties. The final equilibrium flow characteristics and relaxation time of the pressure variation were evaluated as functions of the...
Article
Full-text available
Thermal transpiration is the macroscopic movement induced in a rarefied gas by a temperature gradient. The gas moves from the lower to the higher temperature zone. An original method is proposed here to measure the stationary mass flow rate of gas created by thermal transpiration in a micro-tube heated at its outlet. In addition, by means of a time...
Article
Full-text available
Thermometry techniques have been widely developed during the last decades to analyze thermal properties of various fluid flows. Following the increasing interest for microfluidic applications, most of these techniques have been adapted to the microscale and some new experimental approaches have emerged. In the last years, the need for a detailed ex...
Article
Full-text available
Thermal transpiration pumping in multistage assemblies is computationally investigated. Each stage is formed by combining in series-long microchannels with (a) uniform–uniform (“uni–uni”), (b) converging–uniform (“con–uni”), (c) diverging–uniform (“div–uni”) and (d) converging–diverging (“con–div”) rectangular cross sections. In all four investigat...
Article
Full-text available
Direct measurements of the slip velocity in rarefied gas flows produced by local thermodynamic non-equilibrium at the wall represent crucial information for the validation of existing theoretical and numerical models. In this work, molecular tagging velocimetry (MTV) by direct phosphorescence is applied to argon and helium flows at low pressures in...
Preprint
Full-text available
Gas behavior in systems at microscale has been receiving significant attention from researchers in the last two decades [1-4]. Today, there is an enhanced emphasis on developing new experimental techniques to capture the local temperature profiles in gases at rarefied conditions. The main underlying reason behind this focus is the interesting physi...
Article
Full-text available
The manufacturing process and architecture of three Knudsen type micropumps are discussed and the associated flow performance characteristics are investigated. The proposed fabrication process, based on the deposition of successive dry film photoresist layers with low thermal conductivity, is easy to implement, adaptive to specific applications, co...
Article
Accurate measurement methods are required in the analysis of thermodynamic non-equilibrium effects associated with rarefied gas flows. For example, for the specific case of accommodation coefficients measurements, the quantity of interest is often the mass flow rate along the channel. For this purpose, the following paper presents a new time-depend...
Article
Full-text available
The temperature-driven rarefied gas flow and the associated pumping effects through long channels with linearly diverging or converging cross sections are computationally investigated. The implemented kinetic modeling is well known and relies on the infinite capillary methodology coupled with the mass conservation principle along the channel. The n...
Article
Full-text available
This paper reports the experimental and numerical analysis of time-dependent rarefied gas flows through a long metallic micro-tube. The experimental methodology was conceived on the basis of the constant volume technique and adapted to measure the evolution with time of a transient mass flow rate through a micro-tube. Furthermore, the characteristi...
Article
This paper reports measurements of mass flow rate of nitrogen, R134a, and R600a through a commercially available stainless steel microtube, which closely reproduces the case of gas leakage through micrometric clearances found in compressor valves. The accuracy of the measurements in the whole rarefaction range considered was verified through compar...
Conference Paper
The exchange of momentum and energy in gas flows through microchannels is significantly influenced by the gas-surface interaction. At this scale often the gas is rarefied and therefore non-equilibrium effects in the fluid flow can arise in a layer which extends for a distance equivalent to the mean free path from the walls. Typical examples of non-...
Article
Full-text available
An analytical approach has been developed to take account of the influence of the lateral walls on a stationary isothermal gas flow through a rectangular microchannel. The study concerns pressure-gradient-driven flows in channels where the length is large compared to the critical smallest dimension, namely, the channel height. The calculation of th...
Article
Full-text available
By just applying a temperature difference to a micro-system filled with rarefied gas, it is possible to engender a displacement or a compression of the gas in the temperature gradient direction. This is the Thermal Transpiration phenomenon. In the present work, thermal transpiration has been studied both through an experimental approach, which expl...
Article
Full-text available
Thermal transpiration is the macroscopic movement of rarefied gas molecules induced by a temperature gradient. The gas moves from the lower to the higher temperature zone. An original method is proposed here to measure the mean macroscopic movement of gas in the case of a long circular cross-section glass microtube onto which a gradient of temperat...
Article
Full-text available
Thermal transpiration is the macroscopic movement of gas-particles induced by a temperature gradient. The gas-particles move from the lower to the higher temperature zone. The main aim of the present work is to measure experimentally the flow created by thermal transpiration in a tube heated at its outlet. The experimental system is composed by a c...

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Projects

Project (1)
Project
MIGRATE (Miniaturized Gas flow foR Applications with Enhanced Thermal Effects) is a Marie Skłodowska-Curie Innovative Training Network (ITN) funded by the European Union under the Horizon 2020 Programme (call H2020-MSCA-ITN-2014). Depletion of natural resources combined with the extending footprint of mankind has led to a shift in importance of research and development topics. Emphasis is now focused on resource efficiency as a primary objective. The European Roadmap of Process Intensification identifies several measures: miniaturization, improved heat transfer, and waste heat recovery. It is a well-known fact that minimization of heat and mass transfer resistances lead to tremendous increase in the related transport capacities. Thus, miniaturized devices will play a key role in future industrial applications and transport systems as well as in the re-design of existing processes that directly impact on the daily life of citizens, ranging from industrial technologies to personal equipment. However, there are significant gaps in the fundamental knowledge-base for both mass and heat transfer processes in the micro scale. Current research is primarily focused on phase transition or multi-phase flows, with less attention paid to single-phase gas flows. Measurement systems with sufficiently high temporal and spatial resolution to clarify phenomena in micro scale are not available in many cases, and modelling of such processes is exceptionally challenging. Because of this, pre-calculation and design of miniaturized devices is often based on trial-and-error. This is especially the case for heat transfer using gases. While natural convection systems are described clearly and well-understood, forced convection, enhanced micro-scale heat transfer or heat transfer at reduced pressure levels is not well understood. Optimization of gas-based miniaturized devices for thermal applications with regard to pressure losses, materials, microstructure design, modelling and simulation, let alone measurement and control of processes using such devices are not yet present in technological solution portfolios, although there are many applications of such devices. MIGRATE is intended to address some of the current challenges to innovation that face European industry with regard to heat and mass transfer in gas-based micro-scale processes. A Marie Skłodowska-Curie ETN innovation training network will be established spanning numerical, experimental, theoretical and applied research experts across academia, large scale industry and high-tech SMEs. Within MIGRATE, 15 Early-Stage Researchers (ESRs) will be trained through projects that will cover different aspects of enhanced heat transfer and thermal effects in gases. The presented publication will provide an overview to the activities within the MIGRATE project, depict planned topics and actions as well as present an outlook to future expectations and perspectives. The MIGRATE ITN gathers this understanding by bringing together an intersectoral and multidisciplinary collaboration between eleven academic and 6 industrial participants from 10 European countries. The consortium combines and shares expertise to offer training at an advanced level in various sub-topics.