Browsing NTNU Open by Author "Ringstad, Knut Emil"

Now showing items 1-9 of 9

    • CFD Modelling for Improved Components in CO2 and Ammonia Vapour Compression Systems 

      Ringstad, Knut Emil (Doctoral theses at NTNU;2023:180, Doctoral thesis, 2023)
      Refrigeration and heat-pumping systems are shifting to natural, environmentallyfriendly refrigerants like CO2 to combat global warming. Ejectors are often used in these systems for expansion work recovery to enhance ...

    • CFD-based design algorithm for CO2 ejectors 

      Ringstad, Knut Emil; Banasiak, Krzysztof; Hafner, Armin (Chapter, 2021)
      In this work, a novel CFD-database generation algorithm for CO2 ejectors are presented. The algorithm is explained and its details discussed. A case for CFD database generation is then performed based on an ejector design ...

    • Comparative study of R744 ejector CFD models 

      Ringstad, Knut Emil; Hafner, Armin (Chapter, 2021)
      This work presents a comparative study of four different R744 ejector CFD models at a wide range of operating conditions. The models compared are the homogeneous equilibrium model, the UDRGM mixture model, a homogeneous ...

    • A detailed review on CO2 two-phase ejector flow modeling 

      Ringstad, Knut Emil; Allouche, Yosr; Gullo, Paride; Ervik, Åsmund; Banasiak, Krzysztof; Hafner, Armin (Peer reviewed; Journal article, 2020)
      Ejector-equipped vapor-compression systems for refrigeration and cooling, relying solely on (R744) as a natural working fluid, are perceived to be an eco-friendly and highly efficient solution for many applications. However, ...

    • A detailed review on CO2 two-phase ejector flow modeling 

      Ringstad, Knut Emil; Allouche, Yosr; Gullo, Paride; Ervik, Åsmund; Banasiak, Krzysztof; Hafner, Armin (Peer reviewed; Journal article, 2020)
      Ejector-equipped vapor-compression systems for refrigeration and cooling, relying solely on (R744) as a natural working fluid, are perceived to be an eco-friendly and highly efficient solution for many applications. However, ...

    • Fluid-Structure Interaction in Compressible Viscous Flow 

      Ringstad, Knut Emil (Master thesis, 2018)
      In this master's thesis a ghost-point immersed boundary method for the compressible Navier-Stokes equations using higher order summation by parts operators is described and implemented for two-way coupled fluid-structure ...

    • Machine learning and CFD for mapping and optimization of CO2 ejectors 

      Ringstad, Knut Emil; Banasiak, Krzysztof; Ervik, Åsmund; Hafner, Armin (Peer reviewed; Journal article, 2021)
      In this study, a novel simulation-based algorithm for CO2 ejector design and performance evaluation is presented. The algorithm is based on an automated Computational Fluid Dynamics (CFD) workflow that can account for ...

    • Swirl-Bypass Nozzle for CO2 Two-Phase Ejectors: Numerical Design Exploration 

      Ringstad, Knut Emil; Banasiak, Krzysztof; Ervik, Åsmund; Hafner, Armin (Journal article; Peer reviewed, 2022)
      In this work, a novel ejector design concept of a swirl-bypass nozzle is proposed to improve off-design performance of CO2 two-phase ejectors. The swirl-bypass nozzle allows part of the flow to bypass into the ejector ...

    • Two-fluid CFD model for R744 two-phase ejectors 

      Ringstad, Knut Emil; Hafner, Armin (Chapter, 2020)
      This paper presents early results from a novel two-fluid Eulerian-Eulerian multiphase model for R744 two-phase ejectors, which to the authors knowledge has not previously been presented in literature. As opposed to previous ...