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This paper presents the design of an extended Kalman filter (EKF) as a state-of-charge (SoC) estimator for a lithium–titanate (LTO) battery cell. The design is based on a Thevenin model of the equivalent battery electrical circuit with two parallel resistive-capacitive (RC) elements for the emulation of electrolyte polarization effects. The effectiveness of the proposed SoC estimator is verified through computer simulations on the comprehensive nonlinear battery simulation model featuring battery parameter vs. SoC variations, which is subject to highly dynamic loading regimes.

Supercritical heat transfer has already been applied for decades, as it has several benefits such as improved thermal efficiency of the thermodynamic cycle. Accurate knowledge about supercritical heat transfer and pressure drop of the different working fluids is required to design the heat exchangers and other components used in these systems. In literature, supercritical heat transfer of water and CO2 has already been widely investigated, the research involving refrigerants (for their application in low-temperature heat conversion systems) is however rather scarce. This paper gives an overview of the existing research on supercritical heat transfer. An overview of the applications, general characteristics and the main findings for water and other fluids are summarized. Due to the sharp variations in thermophysical properties, heat transfer and pressure drop cannot be accurately predicted on a single-phase based approach only. An in-detail review of the current research and status of knowledge about supercritical heat transfer of refrigerants is presented. The effect of the different investigated refrigerants and operating parameters on heat transfer and pressure drop, both for heating and cooling applications, is discussed. The remaining gaps in literature are highlighted, which include studies involving larger diameter tubes, horizontal flow, cooling heat transfer and pressure drop estimations and creation of a wider database for a more general correlation development and measurements on newer refrigerants (with low Global Warming Potentials) as these will become increasingly important in the near future. In addition, advances in numerical research should focus on development of suitable turbulence models. Overall, further improving the basic understanding of the fluid structure and occurrence of deteriorated heat transfer, as well as forming reliable models for the thermophysical properties are key in future efforts.

Thermokinetics of Biochar production.

Abstract A new efficient computational approach for the determination of the main design parameters of the parabolic trough receiver is presented. The approach is based on a classical combination of the Monte Carlo ray tracing method for the optical problem and the 3D finite volume method for the thermo-fluid problem. Unlike previous studies, modeling was carried out using a created fully dimensionless thermo-fluid mathematical model and dimensionless numerical algorithm. Criterial complexes (relations between thermophysical, dynamic and geometrical properties) act as dimensionless variables in a mathematical model. A single criterial dependency for describing the temperature fields for any receiver geometry and any heat transfer fluid type was obtained. A proposed solution is correct for any inlet and ambient temperatures. The impact of concentrator surface errors and the design of a tube receiver on temperature fields was studied as well. The present study is the first attempt to mathematically generalize the thermo-fluid analysis in the parabolic trough receiver. A user can efficiently evaluate and predict all thermo-fluid parameters for chosen parabolic trough concentrator geometry with only one dependency without using costly standard software packages. Obtained data is useful for analysis during both the design and operational stages.