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S A Tassou - One of the best experts on this subject based on the ideXlab platform.

  • Transient analysis and control of a heat to power conversion unit based on a simple regenerative supercritical CO2 Joule-Brayton cycle
    'Elsevier BV', 2020
    Co-Authors: Marchionni M, Bianchi G, S A Tassou
    Abstract:

    © 2020 The Authors. Supercritical carbon dioxide (sCO2) heat to power systems are a promising technology thanks to their potential for high efficiency and operational flexibility. However, their dynamic behaviour during part-load and transient operation is still not well understood and further Research is needed. Additionally, there is not enough literature addressing suitable control approaches when the objective is to follow the dynamics of heat load supplied by the topping process to maximise the power recovery. The current Research aims to fill these gaps by proposing a one- dimensional transient modelling formulation calibrated against the major components of a 50 kWe sCO2 test facility available at Brunel University London. The dynamic analysis showed that the system quickly adapts to a 2800s transient heat load profile, proving the flexible nature of the sCO2 system investigated. The turbine by- pass, during startup and shutdown modes of operation, enabled gradual and safe build-up/decline of the pres- sures and temperatures throughout the loop. The regulation of the inventory in the range 20–60 kg allowed a 30% variation of the turbine inlet temperature with lower penalties on system performance than the turboma- chinery speed control. The designed proportional-integral inventory controller showed a rapid response in the control of the turbine inlet temperature around the set point of 773 K during large variations of the heat load.European Union’s Horizon 2020 Research and innovation program under grant agreement No. 680599; Engineering and Physical Sciences Research Council (EPSRC) of the UK under Research grants EP/P004636/1 ‘Optimising Energy Manage- ment in Industry - OPTEMIN’; Centre for Sustainable Energy Use in Food Chains (CSEF), an End Use Energy Demand Centre funded by the Research Councils UK, Grant No: EP/K011820/1

  • Modelling and off-design performance optimisation of a trilateral flash cycle system using two-phase twin-screw expanders with variable built-in volume ratio
    'Elsevier BV', 2020
    Co-Authors: Bianchi G, Marchionni M, Miller J, S A Tassou
    Abstract:

    © 2020 The Author(s). This Research work presents a numerical chamber model of a two-phase twin-screw expander and its further integration in a one-dimensional model of a Trilateral Flash Cycle (TFC) system for low-grade heat to power conversion applications. The novel feature of the expander is the capability of changing the built-in volume ratio (BIVR) of the machine through a sliding valve in the casing that opens an additional suction port. Lowering the BIVR from 5.06 to 2.63 results in an improvement of the volumetric efficiency from 53% to 77% but also in a reduction of the specific indicated power from 4.77 kJ/kg to 3.56 kJ/kg. Parametric analysis on several degrees of freedom of the full TFC system concluded that expander speed and BIVR are the variables that mostly impact the net power output of the unit. An optimisation study enabled the net power output of the TFC system, at design point, to increase from 81 kW to 103 kW.European Union's Horizon 2020 Research and Innovation Programme; Innovate UK; Engineering and Physical Sciences Research Council UK; Research Councils UK; Spirax Sarco Engineering PLC; Howden Compressors Ltd; Tata Steel; Artic Circle Ltd; Cooper Tires Ltd; Industrial Power Units Ltd.(i) the European Union's Horizon 2020 Research and Innovation Programme under grant agreement no. 680599, (ii) Innovate UK (project no. 61995-431253, (iii) Engineering and Physical Sciences Research Council UK (EPSRC), grant no. EP/P510294/1 and (iv) Research Councils UK (RCUK), grant no. EP/K011820/1

  • CFD modelling of finned-tube CO 2 gas cooler for refrigeration systems
    'Elsevier BV', 2019
    Co-Authors: Zhang X, Ge Y, Sun J, Li L, S A Tassou
    Abstract:

    This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) As a main component in a refrigeration system, finned-tube CO2 gas cooler plays an important role to the system performance and thus needs to be thoroughly investigated. To achieve this, some effective parameters including the CO2 and air fluid velocity fields, temperature profiles and heat transfer characteristics at different operating conditions are predicted and analysed by means of Computational Fluid Dynamics (CFD) modelling and simulation. It is noted that CFD modelling can accurately obtain the local heat transfer coefficients of both air and refrigerant sides, which are difficult to be predicted by conventional empirical correlations. This paper investigates the effect of varied operational parameters on local heat transfer coefficients and temperature profiles of the working fluids in a finned-tube CO2 gas cooler by means of CFD modelling. As one of the simulation results, it is found that the approach temperature decreases with increased air inlet velocity. The model has been compared and validated with experimental measurements and literature correlations. The Research methods and outcomes can be used for further investigation and optimization in this area.GEA Searle and Research Councils U

  • Diffuser performance of centrifugal compressor in supercritical CO 2 power systems
    'Elsevier BV', 2019
    Co-Authors: Ss Saravi, S A Tassou
    Abstract:

    This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) The paper focuses on understanding the performance of a vaned diffuser in a supercritical CO 2 compressor using real gas assumptions. The rapidly changing properties of CO 2 in the non-ideal thermodynamic region can have a significant impact on the performance of the diffuser. To account for this, the relationship between the flow properties (i.e. fundamental derivative) and the local geometry (i.e. cross-sectional area of the nozzle) has been discussed theoretically. To examine it analytically, the study has considered the influence of real gas properties on the performance of a vaned diffuser using computational fluid dynamics (CFD) modelling. The selected compressor stage geometry is similar to the compressor impeller tested in the Sandia sCO 2 compression loop facility. The effect of changes in the number of blades and the corresponding changes in the cross throat area on the flow properties such as density and speed of sound were investigated and discussed. The results illustrate that a diffuser with a higher number of blades (smaller throat area) compared to a diffuser with a wider throat area has a higher probability of creating flow instability in the passage stage.European Union’s Horizon 2020 Research and innovation programme and Research Councils U

  • Numerical modelling of a two-phase twin-screw expander for Trilateral Flash Cycle applications
    'Elsevier BV', 2018
    Co-Authors: Bianchi G, S A Tassou, Miller J, Kennedy S, Zaher O, Jouhara H
    Abstract:

    This paper presents numerical investigations of a twin-screw expander for low grade (≤100°C) heat to power conversion applications based on the bottoming Trilateral Flash Cycle. After a thorough description of the modeling procedure, a first set of simulations shows the effect of different inlet qualities of the R245fa working fluid and of the revolution speed on the expander performance. In particular, at 3750 RPM and an inlet absolute pressure of 5 bar, the volumetric and adiabatic efficiencies will increase from 24.8% and 37.6% to 61.2% and 83.1% if the inlet quality in the intake duct of the expander increased from 0 to 0.1. To further assess the effects of inlet quality, inlet pressure and revolution speed on the expander performance, parametric analyses were carried out in the ranges 0-1 inlet quality, 5-10 bar pressure and 1500-6000RPM speed respectively. © 2018 The Author(s).European Union’s Horizon 2020 Research and Innovation Programme under grant agreement no. 680599, (ii) Innovate UK (project no. 61995-431253, (iii) Engineering and Physical Sciences Research Council UK (EPSRC), grant no. EP/P510294/1 and (iv) Research Councils UK (RCUK), grant no. EP/K011820/1

Islam, Andi Asadul - One of the best experts on this subject based on the ideXlab platform.

  • L-GIutamate Profile in Acute Ischemic Stroke After Intra Arterial Heparin Flushing
    Bali Medical Journal, 2016
    Co-Authors: Islam, Andi Asadul
    Abstract:

    -Objective: The intra-arterial heparin flushing (IAHF) is one of the endovascular procedure that in facts have benefit effect to improving the motoric function after acute ischemic stroke, but the exact mechanism not yet known clearly. The L-glutamate is a neurotransmitter that have important role in the brain metabolism. The purpose of this study is to know how the IAHF affect the Glutamate concentration in the blood and muscle function which measured by Manual Muscle Testing-Medical Research Councils (MMT-MRC) in Acute Ischemic Stroke Patients. Method: The thirty-nine patients of acute ischemic stroke that admitted to hospital, was studied of L-Glutamate serum profile. The patients grouping depend on onset (

Giuseppe Bianchi - One of the best experts on this subject based on the ideXlab platform.

  • energy analysis of alternative co 2 refrigeration system configurations for retail food applications in moderate and warm climates
    Energy Conversion and Management, 2017
    Co-Authors: Konstantinos M Tsamos, Giuseppe Bianchi, Y T Ge, Idewa M C Santosa, S A Tassou, Zoi Mylona
    Abstract:

    This study was supported by the Research Councils UK Energy programme, Grant No: EP/K011820/1 and GEA Searle, now Kevlion. The authors wish to acknowledge the cash and in-kind contributions of these organisations as well as the support received from Brunel University London and the RCUK National Centre for Sustainable Energy use in Food Chains (CSEF).

  • two phase chamber modeling of a twin screw expander for trilateral flash cycle applications
    Energy Procedia, 2017
    Co-Authors: Giuseppe Bianchi, Obadah Zaher, Savvas A. Tassou, Stuart Kennedy, Jeremy Miller
    Abstract:

    Research presented in this paper has received funding from: i) the European Union’s Horizon 2020 Research and innovation programme under grant agreement No. 680599, ii) Innovate UK (Project No. 61995-431253, iii) Engineering and Physical Sciences Research Council UK (EPSRC), Grant No. EP/P510294/1; iv) Research Councils UK (RCUK), Grant No. EP/K011820/1. The authors would like to acknowledge the financial support from these organisations as well as contributions from industry partners: Spirax Sarco Engineering PLC, Howden Compressors Ltd, Tata Steel, Artic Circle Ltd, Cooper Tires Ltd, Industrial Power Units Ltd. The authors also acknowledge contributions from Mr. Jonathan Harrison and Mr. Marek Lehocky of Gamma Technologies during the model development.

Jeremy Phillipson - One of the best experts on this subject based on the ideXlab platform.

  • stakeholder engagement and knowledge exchange in environmental Research
    Journal of Environmental Management, 2012
    Co-Authors: Jeremy Phillipson, Amy Proctor, Philip Lowe, Eric Ruto
    Abstract:

    Abstract It is commonly put forward that effective uptake of Research in policy or practice must be built upon a foundation of active knowledge exchange and stakeholder engagement during the Research. However, what is often lacking is a systematic appreciation of the specific practices of knowledge exchange and their relative merits. The paper reports on a 2009 survey of 21 Research projects within the UK Research Councils’ Rural Economy and Land Use Programme regarding the involvement and perceived impact of over a thousand stakeholders in the Research. The survey reveals that most stakeholders were involved as Research subjects or as event participants. Large numbers were also engaged in the Research process itself, including involvement in shaping the direction of Research. Stakeholder engagement is perceived as bringing significant benefits to the process of knowledge production. A close relationship is found between mechanisms and approaches to knowledge exchange and the spread of benefits for Researchers and stakeholders. Mutual benefits are gained from exchange of staff or where stakeholders are members of Research advisory groups. Different stakeholder sectors are also associated with different patterns of engagement, which lead to contrasting impact patterns. Any efforts to alter knowledge exchange processes and outcomes must overcome these differing engagement tendencies. Overall, much greater attention should be given to early processes of knowledge exchange and stakeholder engagement within the lifetime of Research projects.

  • reflexive interdisciplinary Research the making of a Research programme on the rural economy and land use
    Journal of Agricultural Economics, 2006
    Co-Authors: Philip Lowe, Jeremy Phillipson
    Abstract:

    This paper provides an account of the origins and formation of the UK Research Councils' Rural Economy and Land Use (RELU) programme and its approach to promoting interdisciplinary working between social and natural scientists. The programme is set in the context of broader developments in science policy, including a policy discourse centred upon sustainable development and the knowledge economy and associated demands for greater accountability in science. Interdisciplinarity promises Research that will be more relevant and responsive to public needs and concerns. In describing the provenance of the RELU programme, therefore, the paper seeks to lay out the different stages in its initiation and design to show how, to varying degrees, these were open to external scrutiny and influence. The process of developing the programme illustrates that it is not straightforward to make Research agendas and funding more transparent and accountable. It also provides insights into the challenges that interdisciplinarity and accountability present to established science institutions. Copyright 2006 Blackwell Publishing Ltd.

  • reflexive interdisciplinary Research the making of a Research programme on the rural economy and land use
    Journal of Agricultural Economics, 2006
    Co-Authors: Philip Lowe, Jeremy Phillipson
    Abstract:

    This paper provides an account of the origins and formation of the UK Research Councils’ Rural Economy and Land Use (RELU) programme and its approach to promoting interdisciplinary working between social and natural scientists. The programme is set in the context of broader developments in science policy, including a policy discourse centred upon sustainable development and the knowledge economy and associated demands for greater accountability in science. Interdisciplinarity promises Research that will be more relevant and responsive to public needs and concerns. In describing the provenance of the RELU programme, therefore, the paper seeks to lay out the different stages in its initiation and design to show how, to varying degrees, these were open to external scrutiny and influence. The process of developing the programme illustrates that it is not straightforward to make Research agendas and funding more transparent and accountable. It also provides insights into the challenges that interdisciplinarity and accountability present to established science institutions.

Jeremy Miller - One of the best experts on this subject based on the ideXlab platform.

  • two phase chamber modeling of a twin screw expander for trilateral flash cycle applications
    Energy Procedia, 2017
    Co-Authors: Giuseppe Bianchi, Obadah Zaher, Savvas A. Tassou, Stuart Kennedy, Jeremy Miller
    Abstract:

    Research presented in this paper has received funding from: i) the European Union’s Horizon 2020 Research and innovation programme under grant agreement No. 680599, ii) Innovate UK (Project No. 61995-431253, iii) Engineering and Physical Sciences Research Council UK (EPSRC), Grant No. EP/P510294/1; iv) Research Councils UK (RCUK), Grant No. EP/K011820/1. The authors would like to acknowledge the financial support from these organisations as well as contributions from industry partners: Spirax Sarco Engineering PLC, Howden Compressors Ltd, Tata Steel, Artic Circle Ltd, Cooper Tires Ltd, Industrial Power Units Ltd. The authors also acknowledge contributions from Mr. Jonathan Harrison and Mr. Marek Lehocky of Gamma Technologies during the model development.