The determination of steel cleanliness in the as-cast steel ingot 26NiCrMoV145

The content and the type of non-metallic inclusions in the as-cast ingot for open-die forgings made from 26NiCrMoV145 steel were determined. The standard methods for the determination of non-metallic inclusions are suitable only for the wrought steels, so a modified standard method for the determination of the non-metallic inclusions in the as-cast steel was performed. Analyzed samples were taken from three different positions on the ingot. The determination of the type of the non-metallic inclusions was made by EDS analysis. The content of the non-metallic inclusions was determined using an optical microscope.     

An experimental and numerical investigation of heat transfer during technical grade paraffin melting and solidification in a shell-and-tube latent thermal energy storage unit

The latent thermal energy storage system of the shell-and-tube type during charging and discharging has been analysed in this paper. An experimental and numerical investigation of transient forced convective heat transfer between the heat transfer fluid (HTF) with moderate Prandtl numbers and the tube wall, heat conduction through the wall and solid–liquid phase change of the phase change material (PCM), based on the enthalpy formulation, has been presented. A fully implicit two-dimensional control volume Fortran computer code, with algorithm for non-isothermal phase transition, has been developed for the solution of the corresponding mathematical model. The comparison between numerical predictions and experimental data shows good agreement for both paraffin non-isothermal melting and isothermal solidification. In order to provide guidelines for system performance and design optimisation, unsteady temperature distributions of the HTF, tube wall and the PCM have been obtained by a series of numerical calculations for various HTF working conditions and various geometric parameters, and the thermal behaviour of the latent thermal energy storage unit during charging and discharging has been simulated.