M. Hanuszkiewicz-Drapała

The Finite Difference Method and the Numerical Approach for Modeling the Maldistribution of the Flow of Media in Tube-and-Fin Cross-flow Heat Exchangers

ABSTRACT The work deals with thermal and hydraulic modeling of fin-and-tube cross-flow heat exchangers with a non-uniform flow of media. A maldistribution of media flow is not considered in the standard thermodynamic analysis, and the results of such analysis may be too optimistic. The authors applied two modeling methods to include the information about a non-uniform flow of media through the heat exchangers. The finite difference method and the numerical approach are applied in the first and in the second stage of the analysis, respectively. The general assumption is that the real device can be divided into repetitive elements, thus allowing to consider the media flow non-uniformity. The two methods are used for simulations of selected experiments carried out for a single-row fin-and-tube cross-flow heat exchanger. A traditional computational analysis is also performed and a comparison of the results is made. The results confirmed the applicability of the proposed methods.

3D Numerical Analysis Of The Temperature Fields In Cold Store Foundations

The subject of analysis is the temperature field in cold store foundations protected from freezing by a system of heating pipes. The pipes can include an electric heater or a hot liquid medium. The foundations consist of several layers. Freezing of the water in the foundation can cause heaving of its layers and, in an extreme case, can destroy the building structure. The considered heat transfer problem in the cold store foundations is described by a typical transient initial-boundary heat conduction value problem with Stefans boundary condition on the phase change interface. The problem has been solved using FEM and the spatial averaging technique has been employed to take into account phase change effect. Results of 3D calculations of the temperature field in the cold store foundation are presented and discussed, particularly the influence on the temperature field of the heat transfer from surroundings of the cold store and of the heat transfer through bearing piles.