Eksperimentalno i numeričko istraživanje termo-strujnih procesa u paketu perforiranih ploča

Abstract

One of the most important characteristics of heat exchangers, besides thermal efficiency, is their compactness or surface area to volume ratio. The need to achieve high efficiency in a compact unit with high operating pressure has led to the development of heat exchangers with perforated plates or, as they are called in the literature, the Matrix Heat Exchangers (MHE). In this PhD thesis experimental and numerical research was undertaken to measure the thermal and flow characteristics of an assembly of perforated plates, in an effort to obtain indications for engineering calculations. The study was undertaken in the Laboratory for Thermal Engineering at the Faculty of Mechanical Engineering, Niš. In the experimental part of the study, packages of one, two and three 2 mm thick plates were used, with a porosity of 25.6% and a square arrangement of holes that were 2 mm in diameter. Water was used as the heating fluid, while the heated fluid was air. The package of plates was placed in the experimental chamber which had a fan as an inlet, with the ability to control the flow. The fluid flow rate, pressure drops and the temperatures of the fluids at the inlet and outlet of the chamber, as well as the temperature of air between the plates, were measured at the pre-defined locations in the perforated plate heat exchanger. Also, the pressure drop was measured for the perforated plate package with and without the water collector. In the numerical part of this research, the PHOENICS 2014 software package was used. In the first part of the numerical study the heat transfer from plates with the porosity from 10 to 50% was investigated. In the second part of the numerical study, a package of three plates was established and the effect of distance between the plates was also examined. Experimental results and the results of other authors were used to validate the numerical experiment. iv On the basis of experimental and numerical results, criterial equations for heat transfer and formulas for pressure drop equations were established.