Now showing items 21-40 of 43

    • Modeling for control of run-of-river power plant Grønvollsfoss 

      Vytvytskyi, Liubomyr; Sharma, Roshan; Granstrøm, Ingunn; Lie, Bernt (Conference object; Peer reviewed, 2015-11-25)
      Design of optimal operation and control of a run-of-river hydro power plant depends on good models for the elements of the plant. River reaches are often considered to be shallow channels with free surface flow. A typical ...
    • Modelling and control of a typical high head hydropower plant 

      Zhou, Wenjing; Lie, Bernt; Glemmestad, Bjørn (Conference object; Peer reviewed, 2011)
      This paper describes an effective mathematical model of a hydropower plant and how a decentralized control strategy for frequency and terminal voltage can be simulated. Several dynamic equations are presented for each ...
    • NEQ rate based modeling of an absorption column for post combustion CO2 capturing 

      Jayarathna, Sanoja A.; Lie, Bernt; Melaaen, Morten Christian (Journal article; Peer reviewed, 2011-04-01)
      Post combustion CO2 capture via absorption into aqueous alkanolamine systems is considered to be the most mature and potential technique for CO2 removal from the power plants' exhaust gases. Modeling and simulation of such ...
    • Numerical solution of the Saint Venant equation for Non-Newtonian fluid 

      Agu, Cornelius Emeka; Lie, Bernt (Conference object; Peer reviewed, 2014)
      Non-Newtonian fluid flow through a Venturi channel is studied using the Saint Venant equation. The nonlinear hyperbolic equation is numerically tricky to solve, therefore in this study, we consider the finite volume method ...
    • On-Off and PI control of methane gas production of a pilot anaerobic digestion reactor 

      Haugen, Finn; Bakke, Rune; Lie, Bernt (Journal article; Peer reviewed, 2013)
      A proposed feedback control system for methane flow control of a real pilot anaerobic digestion reactor fed with dairy waste is designed and analyzed using the modified Hill model, which has previously been adapted to the ...
    • Optimal design and operation of a UASB reactor for dairy cattle manure 

      Haugen, Finn; Bakke, Rune; Lie, Bernt; Hovland, Jon; Vasdal, Knut (Journal article; Peer reviewed, 2015-02-01)
      Optimal design and operation of a planned full-scale UASB reactor at a dairy farm are determined using optimization algorithms based on steady state simulations of a dynamic AD process model combined with models of the ...
    • Optimal Operation of the Peat Drying Process in Steam Tube Dryers 

      Kulakovsky, Leonid; Rosen, Victor; Sharma, Roshan; Pfeiffer, Carlos; Lie, Bernt (Conference object; Peer reviewed, 2015-11-25)
      Ukraine is an energy-dependent country and aims to reduce the import of natural gas, heat, and power in general. This implies extracting fuel from her own natural resources; one relevant and readily available energy carrier ...
    • Oxygen Effects in Anaerobic Digestion II 

      Botheju, Deshai; Lie, Bernt; Bakke, Rune (Journal article, 2010)
      Standard models describing bio-gasification using anaerobic digestion do not include necessary processes to describe digester dynamics under the conditions of oxygen presence. Limited oxygenation in anaerobic digestion can ...
    • Population balance modelling for fertilizer granulation process 

      Vesjolaja, Ludmila; Glemmestad, Bjørn; Lie, Bernt (Journal article; Peer reviewed, 2018)
      Few granulation plants are operated optimally. It is common to operate granulation plants below their maximum design capacity, and in many cases, periodic instabilities may also occur. From a process control and optimization ...
    • Power System Stability Using Modelica 

      Øyvang, Thomas; Winkler, Dietmar; Lie, Bernt; Hegglid, Gunne John (Conference object; Peer reviewed, 2014-12-09)
      This paper is concerned with power system modeling using the Modelica language in comparison to a traditional simulation tool. Though most common power system simulation tools are computationally efficient and reasonably ...
    • Relaxed Ziegler-Nichols closed loop tuning of PI controllers 

      Haugen, Finn; Lie, Bernt (Journal article; Peer reviewed, 2013)
      A modification of the PI setting of the Ziegler-Nichols closed loop tuningmethod is proposed. The modification is based on a combination of the Skogestad SIMCtuning formulas for ´´integrator plus time-delay´´ processes ...
    • Second Order KP Scheme for the Solution of flow in a Venturi Channel 

      Dissanayake, Susantha; Sharma, Roshan; Lie, Bernt (Journal article; Peer reviewed, 2018)
      In many different applications, a Venturi channel is used as a tool to compute fluid flow rates. The Saint-Venant equation is a hyperbolic type Partial Differential Equation (PDE) which can be used to model fluid flows ...
    • Semi Discrete Scheme for the Solution of Flow in River Tinnelva 

      Dissanayake, Susantha; Sharma, Roshan; Lie, Bernt (Chapter; Peer reviewed, 2016)
      The Saint-Venant equation is a mathematical model which could be used to study water flow in an open channel, river etc. The Kurganov-Petrova (KP) method, which is a second order scheme, is used to solve the Saint-Venant ...
    • Simulation of Transcritical Flow in Hydraulic Structures 

      Agu, Cornelius Emeka; Lie, Bernt; Elseth, Geir (Conference object; Peer reviewed, 2015-11-25)
      In hydraulic engineering, transcritical flows are often required in some applications. One example is in a Venturi channel where the occurrence of critical depth is used to estimate flow rate in the channel. In this paper, ...
    • Simulation of Transcritical Flow in Hydraulic Structures 

      Agu, Cornelius Emeka; Lie, Bernt; Elseth, Geir (Conference object; Peer reviewed, 2015-11-25)
      In hydraulic engineering, transcritical flows are often required in some applications. One example is in a Venturi channel where the occurrence of critical depth is used to estimate flow rate in the channel. In this paper, ...
    • State Estimation and Model-Based Control of a Pilot Anaerobic Digestion Reactor 

      Haugen, Finn; Bakke, Rune; Lie, Bernt (Journal article; Peer reviewed, 2014-02-22)
      A state estimator and various model-based control systems have been designed for a real anaerobic digestion (AD) pilot reactor fed with dairy manure. The model used is a modified Hill model which is a relatively simple ...
    • State Estimation and Model-Based Control of a Pilot Anaerobic Digestion Reactor 

      Haugen, Finn; Bakke, Rune; Lie, Bernt (Journal article; Peer reviewed, 2014-02-22)
      A state estimator and various model-based control systems have been designed for a real anaerobic digestion (AD) pilot reactor fed with dairy manure. The model used is a modified Hill model which is a relatively simple ...
    • State estimation and model-based control of a pilot anaerobic digestion reactor 

      Haugen, Finn; Bakke, Rune; Lie, Bernt (Journal article; Peer reviewed, 2014)
      A state estimator and various model-based control systems have been designed for a real anaerobic digestion (AD) pilot reactor fed with dairy manure. The model used is a modified Hill model which is a relatively simple ...
    • Structural observability analysis of large scale systems using Modelica and Python 

      Perera, M. Anushka S.; Lie, Bernt; Pfeiffer, Carlos Fernando (Journal article; Peer reviewed, 2015)
      State observability of dynamic systems is a notion which determines how well the states can be inferred from input-output data. For small-scale systems, observability analysis can be done manually, while for large-scale ...
    • Study of Fluidization Regimes using OpenFOAM Computational Fluid Dynamics 

      Welahettige, Prasanna; Lie, Bernt; Vågsæther, Knut; Moldestad, Britt Margrethe Emilie (Journal article; Peer reviewed, 2017)
      The objective of this study was using computational fluid dynamics simulation with OpenFOAM to study the fluidization properties for four types of particles classified as Geldart A, B, C and D. Fluidization regimes were ...