Rakhi Rakhi

Brandenburg University of Technology Cottbus - Senftenberg | BTU · Mechanical Engineering

To render future SFR more robust and safe, certain BDBE have been considered in the recent years. A Core Disruptive Accident leading to a whole core meltdown scenario has gained the interest of researchers. Various design concepts and safety measures have been suggested and incorporated in design to address such a low probability scenario. A core c...

The incompressible temporally developing turbulent boundary layer (TBL) is analysed using the map-based stochastic one-dimensional turbulence (ODT) model. The TBL is a canonical flow problem, which is, in the present study, formed by a planar moving wall and a free stream at rest. An understanding of this idealised flow is of fundamental relevance...

A map-based stochastic approach, One-Dimensional Turbulence (ODT), is applied to analyze the incompressible spatially developing turbulent boundary layer (SBL). In the present study, the SBL is formed by a plane moving wall and a free stream at rest. The flow variables are resolved on all scales along a 1-D domain. A deterministic process represent...

A one-dimensional model, LOGEcat is used to develop a detailed surface reaction mechanism for modeling the steam reforming of methane over a nickel-based catalyst. The focus of the paper is to develop a kinetically consistent surface reaction mechanism. The two terms, kinetically and thermodynamically consistent mechanisms , will be used frequently...

Steam reforming of hydrocarbons is a well established chemical process which provides synthesis gas (H2 and CO). These synthesis products can hence be converted to numerous valuable basic chemicals. For the industrial application of steam reforming, a detailed understanding of the process is a prerequisite. Models that capture the detailed homogene...

In this study the methanation of synthesis gas (syngas) is investigated with a focus on achieving maximum methane and minimum CO by full methanation of CO2. For this study, we have considered a comprehensive thermodynamics analysis of CO2 hydrogenation. This will help us to understand the thermodynamic behaviour of the reactions involved in the met...

The production of green gases using power-to-gas in industry and the energy sector is essential for reducing the carbon footprint. In this process, green H2 and CO2 are converted into synthetic methane using nickel catalysts. The carbon dioxide can be obtained from the environment or from point sources such as waste-to-energy plants, combined heat...

Even if huge efforts are made to push alternative mobility concepts, such as electric cars and fuel-cell-powered cars, the significance and use of liquid fuels is anticipated to stay high during the 2030s. Biomethane and synthetic natural gas (SNG) might play a major role in this context, as they are raw material for chemical industry that is easy...

This work presents a numerical investigation of oxyfuel combustion of methane in a gas engine with passive pre-chamber. A three-dimensional (3-D) computational fluid dynamics (CFD) solver with detailed chemistry in Converge v3.1.8 is used to predict the ignition and turbulent flame propagation in the engine. The reaction kinetic model for methane o...

In this paper, we have used a thermodynamic model for the first time to investigate the steam and oxidative reforming of methane over a nickel catalyst in a wide temperature range, i.e., 400–1200 K. The available literature focus on the kinetic models and hence, thermodynamic models require attention to understand the behaviour of the thermochemist...

In the field of catalysis, dry reforming, that is, methane reforming with , is in the focus due to growing environmental concerns about oil depletion and global warming with a desire to produce synthesis gas. However, this process can lead to the formation of carbon, which can cause catalyst deactivation, especially at industrial conditions. Nevert...

The reforming of light hydrocarbons to produce synthesis gas, H2 and CO, is an important intermediate for manufacturing valuable basic chemicals and synthesis fuels. In order to understand these reforming processes better, elementary step reaction mechanisms are developed. In the available literature, the surface reaction mechanisms are usually ach...

Within this paper, we aim to understand the direct production of synthetic natural gas from CO2 and H2 in a Sabatier process based on a thermodynamically consistent elementary reaction mechanism. For that purpose, a series of NiO-SiO2 catalysts with varying Ni content have been experimentally investigated. The rate and selectivity of CO2 methanatio...

A thermodynamic model is developed using a one-dimensional model, LOGEcat to understand the dry reforming of methane over nickel-based catalysts. To do so, we have extended our previously developed mechanism (Rakhi and Shrestha in React Kinet, Mech Catal 135:3059–3083, 2022) which contains 21 reversible reactions by adding 5 more reversible reactio...

We have developed a kinetically consistent detailed surface reaction mechanism for modeling the oxidation of methane over a nickel-based catalyst. A one-dimensional model, LOGEcat based on the single-channel 1D catalyst model, is used to perform the simulations. The original multi-step reaction mechanism is thermodynamically consistent and consists...

Steam reforming is a promising route to convert natural gas into syngas - a mixture of H2 and CO, used as a feed stock e.g. for ammonia, methanol and Fischer-Tropsch synthesis processes. For the industrial application of steam reforming, a detailed understanding of the process is a prerequisite. Models that capture the detailed homogeneous and hete...

The reduction of greenhouse gasses such as CO2 and CH4 is becoming necessary due to global environmental problems. The reforming of light hydrocarbons is a particularly efficient process for producing synthesis gas, H2 and CO, from greenhouse gasses [1]. The steam reforming of methane is the most important method to produce syngas in industry by us...

The reduction of greenhouse gasses such as CO2 and CH4 is becoming necessary due to global environmental problems. The reforming of light hydrocarbons is a particularly efficient process for producing synthesis gas, H2 and CO, from greenhouse gasses. The steam reforming of methane is the most important method to produce syngas in industry by using...

A map-based stochastic approach, One-Dimensional Turbulence (ODT), is applied to analyze the incompressible spatially developing turbulent boundary layer (SBL). The application of ODT to investigate the turbulent boundary layer is revisited for the spatial ODT formulation as it is physically more relevant. In the present preliminary study, the SBL...

A map-based stochastic approach, One-Dimensional Turbulence (ODT), is applied to analyze the incompressible spatially developing turbulent boundary layer (SDTBL). The application of ODT to investigate the turbulent boundary layer is revisited for the spatial ODT formulation as it is physically more relevant. In the present preliminary study, the SB...

We investigate incompressible temporally developing turbulent boundary layers for the first time using the One‐Dimensional Turbulence (ODT) model. ODT is spatially fully resolved along the 1D domain, only turbulent advection is represented by stochastic mapping events. We compare the mean and root mean square velocity profiles with the Direct Numer...

In the present study, we focus on a new application of the One-Dimensional Turbulence (ODT) model to a temporally developing turbulent boundary layer. Due to dimensionality reduction in ODT, this model achieves major cost reductions as compared to full 3D simulations and is, thus, able to explore large parameter regimes, which may be very interesti...

A core catcher below the grid plate has proved to be inevitable as an in-vessel device in Sodium Cooled Fast Reactor (SFR) for safe retention of core debris arising after severe accident. The present study aims to analyse the cooling capability of multi-tray core catcher by natural convection for a typical 500 MWe SFR. First, the capability of sing...

For safe design of future Sodium Cooled Fast Reactors (SFR), certain Beyond Design Basis Events (BDBE) has been considered in recent years. Various safe design concepts have been incorporated in the design to address such low probability events (probability of occurrence <10^-6/ry). A core catcher is inevitable as an in-vessel retention device for...