J. Skorek

Inverse approach and sensitivity analysis for identification of ingot-mould thermal resistance in continuous casting of metals

The problem of appropriate location of the sensors for identification of ingot – mould thermal resistance during continuous casting of metals is the subject of the paper. Analysed problem belongs to the group of inverse problems. The present work shows also the method of identification of unknown thermal resistance using the temperature measurements at the number of sensors located in the wall of the mould. The influence of the location of the sensors on the results of identification is analysed. The best location of the sensors results from the sensitivity analysis for the steady-state inverse heat conduction problem. Validation of the proposed inverse method is realized by comparison of the results taken from solution of inverse and direct problems. Several numerical examples are presented and analysed.

Identification of the heat fluxes and thermal resistance on the ingot-mould surface in continuous casting of metals

Identification of thermal resistance of the gas-gap between the ingot and mould, as well as the heat flux distribution on the phase change from the solid side during continuous casting of metals is the subject of this article. Analysed parameter estimation problems of the steady-state heat conduction belong to the group of inverse problems. The presented work shows the possibility of applying the least square adjustment method with a priori data for the identification of thermal resistance, the interphase location as well the heat flux distribution on the phase change from the solid side and the temperature field within the ingot and mould. The most important feature of the approach is that the unknown thermal resistance of the gas-gap is obtained from the temperature measurements at a number of sensors located in the wall of the mould, and some sensors located in the ingot, by solving the appropriate inverse problem. The validity of the solution of the inverse problem is checked by comparison with the results of direct problem. In this work, a front-tracking method with an automatic mesh generation finite element technique (so called deforming or moving finite-elements) for steady-state equation conduction-advection problems is developed. Such an approach makes it possible to find the exact solid-liquid interface location, because it is the integral part of the solution. Due to the strong convective nature of the problem (casting velocity, thermal parameters) the special up-wind technique is applied.

Inverse finite element technique for identification of thermal resistance of gas-gap between the ingot and mould in continuous casting of metals

Identification of thermal resistance of the gas-gap between the ingot and mould during continuous casting of metals is the subject of the present article. Analysed parameter estimation problem of the steady-state heat conduction belongs to the group of inverse problems. The present work shows the possibility of applying the least square adjustment method with a priori data for identification of thermal resistance as well as the interphase location and the temperature field within the ingot and mould. The most important feature of the approach is that the unknown thermal resistance is identified by solving appropriate inverse problem from the temperature measurements at the number of sensor located in the wall of the mould. The validity of the solution of the inverse problem is checked by comparison with the results of direct problem. In the present work, a front-tracking method with an automatic mesh generation finite element technique (so-called deforming or moving finite-elements) for steady-state equation conduction–advection problems is developed to build the mathematical model of the heat transfer process. Such an approach makes us possible to find solid–liquid interface location, because it is the integral part of the solution of the considered problem. Due to the strong convective nature of the boundary problem (casting velocity, thermal parameters) the special up-wind technique is applied to avoid the oscillation of numerical results.

Optimal dynamic filtration approach for inverse heat conduction problems with moving body

A Kalman filter method in conjunction with the nonuniform control volume methodology is adopted as a numerical tool for solving two-dimensional inverse heat conduction problems for a moving body. This work focuses on estimation of the transient temperature in the solid region of the workpiece during welding process that involves a moving heat source. The following parameters having major influence on the numerical solution are considered: the welding speed, thermal properties, the steps size (such as δx, δy, time step), the number of the sensors and the location of the sensors. The noise in measurement data is also considered to validate the method of solution. The accuracy of the numerical solution for inverse problem is examined by comparing the results with direct solution of the problem. The results show that this method can be the powerful tool for solving inverse heat conduction problems, with or without moving heat sources.

Small‐scale co‐generation for building applications ‐ energy demand analysis at demonstration site and optimal sizing of the CHP plant

Abstract Aspects of using the small‐scale combined heat and power modules in buildings is presented in this paper. At first the problems of energy demand analysis, which is the key point of a co‐generation plant sizing procedure, are discused. Then the demonstration project of a small‐scale co‐generation plant is presented. The plant is fuelled with natural gas, and it supplies energy to a group of three different buildings. Basing on this case, the problems of optimal sizing of a small‐scale CHP plant for a building energy supply system are presented and discussed. Calculation procedures are shown together with the results of sample analysis. The factors influencing the final configuration of the system are indicated.

Evaluation of the influence of liquid fuel atomization on fuel consumption during heating of solids in a furnace

Different parameters of fuel atomization can influence the intensity of thermal radiation of the liquid fuel flame. Investigations which were carried out by the authors proved that the fuel consumption required for heating up the charge in the furnace can be reduced when using appropriate atomization of the fuel. That effect depends mainly on the temperature level within the furnace, and is more visible for higher temperatures.

Results of experimental investigations of the non-throttling Granryd refrigerator

The operation of the non-throttling Granryd refrigerator has been analysed. The experimental installation is presented. The measurement method and obtained results are presented and discussed. The mathematical model of the process was also built to analyse the influence of several design and operation parameters on the efficiency of the refrigerator. The importance of the internal thermal insulation of the expansion tank has been pointed out.

Novel approach for identification of the thermal resistance of the gas-gap between the ingot and mould in the continuous casting of metals

Publisher Summary This chapter presents the identification of thermal resistance of the gas gap between the ingot and mould during continuous casting of metals. Analyzed parameter estimation problem of the steady-state heat conduction belongs to the group of inverse problems. It shows the possibility of applying of the least square adjustment method with a priori data for identification of thermal resistance as well as the phase change location and the temperature field within the ingot and mould. The important feature of the approach is that the unknown thermal resistance is obtained from the temperature measurements at the number of sensors located in the wall of the mold by solving appropriate inverse problem. The validity of the solution of the inverse problem is checked by comparison with the results of direct problem. Several numerical examples are presented and analyzed. Numbers of theoretical models and experiments have been evaluated to describe thermal resistance in processes of continuous casting. Phase change, solidification shrinkage, thermal contraction are mentioned.